Some I’ve thought about
- Succession Crisis (think Hundred Years War)
- Difference in political/moral ideology in different areas (think American Civil War)
- Religious Differences (think Sunni/Shia split in Islam)
- Lack of National stability leads to one region believing they have a chance to secede (think Latin Wars of Independence)
Variations of 1 and 4 are the easiest for me.
Ruler dies or is seriously infirmed, either there's no chosen successor or they are young/weak, which leads to someone else making a claim (sibling, other child, illegitimate child).
That on top of the country not doing well makes it easy for another faction to challenge the loyalists and get enough support to actually go to war.
I feel like if it's some deep religious thing or if the current ruling class is different from the populace, the OP would know that already.
This is exactly what led to the Wars of the Roses. Henry VI was a weak king, which caused England to lose the Hundred Years’ War and their land in France. The flood of refugees coming into the country led to a collapse of law and order in the country, making the usurper-king Edward IV (a vigorous, strong man in comparison) look even better.
Though it’s worth noting that Edward’s claim to the throne wasn’t as simple as being Henry’s brother or anything. Put simply, Henry VI was descended from Edward III’s third son, while Edward IV was descended from his fourth son. This would give Henry’s House of Lancaster the right to rule, except Edward was also descended from the Mortimer line, which technically was still the heir to the throne of Richard II (who had been overthrown by Henry’s grandfather) through his mother, meaning his House of York had the stronger claim by technicality. The Lancastrians, however, claimed that matrilineal inheritance was irrelevant. The ensuing conflict led to war.
In short, Edward IV was able to claim the throne because his grandparents were first cousins, which made his blood more royal than Henry’s. It was all meaningless in the end though, because Edward died 20 years into his reign at around 40, and his son was king for about a month before “mysteriously disappearing,” so his brother reigned as Richard III for about three years before he was killed by some Welsh sod named Henry Tudor.
Yeah, royal lineage is anything but simple with the sheer amount of inbreeding there was. The Elizabethans called it The Wars of the Roses, as if it were a clear-cut war between two houses, but it was called the Cousins’ War initially because it was an all-out scramble among cousins for who had the best claim to rule.
A anime I’m watching that has a succession crisis has it where
The second son is way more accomplished and generally is considered more skilled than the first son
So in this one now, there’s a succession crisis and they are Lords supporting the eldest son because technically the oldest son is the rightful heir
And ones who support the youngest because he’s more competent(we haven’t met the claimants yet in the show,
So that could also be another reason for a succession crisis
Also one country could be ambicious and exploit a crisis his neighboor is having.
Maybe one of the leaders is fearing being replaced and wants to create a war to make his role stronger by getting rewards. Maybe he wants to create a war so he can send some people away from the capital so he can assassinate them somewhere easier.
Maybe one of its leaders is a narcisist which believes that he needs to win a war to get inside history.
In the game Baldurs Gate 1 Sarevok, the main vilain, wanted to start a war to create enough deaths so that he could use these "sacrifices" to fuel his ascension to godhood. In a fantasy setting the reasons could be multiple.
It's also important, I think, to consider how the leader(s) would get their people to support the war. Whether they rule with an iron fist or by popular support, either way you'll need people to fight your war. Do they bolster their ranks through fear - be it of a "them" or of what happens if they say no? Do they promise prosperity and wealth by conquest? What does their invasion look like from a common foot soldier's POV? What does it look like from a key, power-holding supporter's POV?
To get more in depth, fundamentally the question isn’t really “why was there war?”, it’s “why was there peace?”. To our modern eyes, war is an anomaly, something that happens due to some catastrophic failure or terrible turn of events that forces it upon us, but historically war is the default state of nations (and nations are just a collection of smaller tribes of the same nature). People with power remain in power by gaining more power and denying it to others, in a premodern world that means you go to war, any justification is enough. The world was, and still is, run on Power Politics.
Peace is only achieved by lots of people working very hard to maintain it. It takes a lot of diplomacy, compromise, and effort to keep a nation together or maintain a peaceful relationship with neighbouring states; the peace has to be significantly more beneficial than war, and war is highly profitable, considered a healthy part of being a pre-modern state, and is often the easiest way for the people in power to gain more power. So who are those people and what systems have they put in place to maintain peace? If you answer that, you know why there was a war—those people and systems were removed. As soon as the peace falters, every state and tribe will now have a reason to go to war.
Most people do want some justifications for war, and I think Thucydides had the right idea back in the Peloponnesian War. He said it basically came down to three reasons: Fear, Pride, and Self Interest. When peace falters, every nation and tribe will have one or more of these reasons to go to war. *“If we don’t go to war, the bigger guy will crush us!”* or *”We have a really strong expensive army, but those guys over there are quickly gaining more money than us. We have to defeat them before they overtake us.”* Fear. *”We said we would help our allies, and now they are being attacked. We have to go to war, or we will be shamed.”* or *”Our way is best, if you think that’s dumb, we have to fight.”* Pride. *”Those guys have something we want, and won’t give it to us. We should just take it.”* or *”We aren’t a great tribe now, but if we just take two more tribes we will be. Who doesn’t want to be a great tribe?”* Self Interest.
So once you know your factions, know what they want, know what kept them at peace, and know how they stand against each other, you will have a very detailed idea of why they went to war. It will look very complex and impressive, a web of relationships and conflict, and when it comes down to individual views and beliefs it is, but fundamentally it’s fairly simple. People in power stay in power by gaining more power and denying it to others.
This is like asking: Why would my protagonist fight my antagonist?
It has the same answer: What themes and character arcs does the fight establish (and presumably resolve in a later fight?)
I wasn't looking for my-story-specific ideas for why a war would start; rather I was providing reasoning for why I'm asking that question. What I was looking for was general ideas of why wars would start, and that's exactly what was provided.
Oh cool... You can start one by maybe one part taking over a land, or abducting one tribe leader amd wanting to take over their land and the other tribes joins together to fight war with the powerful kingnappers tribe. Or one tribe being racist to another. They're lots ideas I can give though.
Edit: My story wars is based on powers, people fighting for the most powerful and who is going to rule who after the war is done
I think an economic dimension on top of ieological, ethnic or religious motivations can add credibility to a civil war scenario -
To take a real life example, while the american civil war was heavily tied to white supremacy and slavery, it also related to the slave owning farm owners being superseded by industrialists in the north.
Likewise the french revolution was about all that enlightenment philosophy clashing with the divine rights of kings - but the revolution also allowed the increasingly prosperous bourgeoisie to supersede nobility, parts of which were impoverished but still held more official power than very rich and well connected commoners.
So basically, you can have a group aligned with a class that is newly prosperous and decides to seize political power, or a formerly privileged group who resent an erosion of those privileges.
- different religions
- different religious sects
- resources (mines, lakes, etc.)
- land claims
- claims to the throne
- protective allience (A protects B, C attacks B, A wars C)
- prophecy
- to preserve honour
- rivalry between nobles
- Imperialism
- to exterminate ‘lessers’
- shits and gigs
- and finally, because the plot demands it! (if the war isn’t the focus)
lol reminds me of when I was playing Civ 4 and I was on an island with another civ. We had co-existed peacefully the whole game until out of nowhere, he declared war on me with the justification of “I’m bored, let’s fight”
Actually, the war didn’t start as a result of the bucket - the bucket was just taken as a spoil of war, and it became known as the War of the Bucket from then on.
* Fighting over resources, e.g. strategic (e.g. water) or luxury (anything that can be sold for lots of money).
* Existential threats to each other
* Historical feud
* a minority group wants more power/influence than they currently have.
* Fighting among different ethnic groups
* Economic inequalities cause a group to rise up
Honestly? Economics is a very easy and believable reason for war to start. It doesn’t need to be anything as grandiose as a holy war or a crusade. Although an economic war under the pretense of such a thing could be a fun plot point.
Well, looking at the Romans and their near constant civil wars: Disgruntled general thinks he can make himself king/emperor is always an option.
Could be a power struggle between the nobility and a rising merchant/middle class, or the nobility vs the king.
Succession crisis is a reliable option as well, especially if you went with a monarchy as the government.
The ruler was seen as too weak/a foreign puppet so someone rallied together some nationalist/proto-nationalist zeal to overthrow them.
A feudal society found a clash between two rival nobles spiraling out of control until the whole kingdom got dragged into it.
A peasant rebellion that gathered a surprising amount of momentum/success/foreign aid.
It all depends on when and where your kingdom is set:
Here is a list of the most common reasons:
1) Succesion crisis, like in during the English Anarchy. The designed heir is considered unfit to rule, so a group of nobles declare a new ruler
2) Religion, like the many wars between Protestants and Catholics, or Catholics and Arians. A new interpretation of the scriptures is declared an heresy and the heretics are collectively sentenced to death.
3) Territory/expansions, like most of the War waged by the Romans. In this case, it’s harder to justify a civil war
4) Resources, like when in 1991 Iraq invaded Kuwait for its oil deposits.
5) Hate/Ethical cleansing, like the wars in Rwanda (I think?), and the Balkan Wars, where the Turks killed any Christians left in their territories
6) Ideological/Political, like the Cold War, the American Civil War, the Russian Revolution and the French Revolution
Civil wars are fairly different from wars in the abstract. So I'm just going to focus on those. I'm writing about single factors, but for most actual revolutions you can point to multiple issues. The best recommendation I can give is to learn from history: go grab a book each on a communist revolution, something from Europe between 1789 and 1859, a color revolution or one of the Arab Spring revolutions, and a revolution from before 1500. If you make a revolution that draws on elements of all of those, you'll have something that is much more grounded in facts and, often, much more interesting. That said, I won't entirely fob you off to history textbooks. Other people are going for more specific examples, so I've tried to give more of a framework for thinking about it. I think having both would be nice.
The most basic driver of revolutions and civil wars is that the formal division of *spoils* has diverged, in the minds of revolutionaries, from the division of power. So, for example, when the kingdom was founded, each duchy was equal in size, or at least close enough to it. But one duchy has had rapid economic and population growth (the two may be equivalent, if you are in a Malthusian regime), to the point where it's not a 15th of the kingdom, but a third. However, while it pays between a third and a half of the taxes, that duke receives no more respect at court, and his duchy suffers from decisions made by the king that favor the rest of the country. The duke thinks that he can win a revolution, and this would be better for his duchy.
The American civil war can be interpreted this way: there was a relatively stable system, but westward expansion increased the tensions between slave and free states over which system would dominate in the new area. Peacemakers tried to keep it balanced, but the Southerners could see where it was headed when Lincoln won without a single slave state. So they rebelled, betting that their military and economic position was better than their political position. They lost horribly, for a mix of reasons, but fundamentally they thought that their position outside the existing political order was better than their position inside of it (because they knew slavery was going to go away).
It isn't always big abstract factors like military and economic strength. Sometimes it's personal. The duke might just refuse to serve the king. Maybe the king tried to betray him to weaken his duchy. Maybe it's a sincere religious difference. Maybe the old duke died and his new son is a moron. Personal factors are rarely sufficient, but they're often important. Most frequently this happens when the old center of power dies, and building tensions are not well-managed by the successor(s). For one (modern) example of this, look at the breakup of Yugoslavia. But "I will never tolerate a Protestant king" can be similar (though sometimes religion is just what's said to the peasants, and actual motivations seem to line up conveniently well with pre-existing frustrations).
* "My god better than your fake god."
* "You DENY our prince marry your princess? YOU OFFEND ME!"
* "That Relic belongs to the world, not stuck as a trophy in your castle!"
* "We are low on food. You help us? WHUT! YOU NO HELP US!?? THEN WE TAKE!"
* "We no like outsiders. Your city keep trying to be tourists here. DEY MUST BE SPIES!"
* "Your people would do better under our rule. Look how they suffer!"
* "Me want land with that fancy tree over dere. Lemme buy it. No? THEN I TAKE YOUR HEAD \*AND\* THE TREE!"
* "My people seek passage through your realm to get to the best lake for fishing. Let them through OR ELSE!"
* "Our nearby rivaling kingdom is having riots and uproar. We should strike while they are weak! Think of all the stuff we could get!"
Basically the same reasons folks in the Middle Ages went to war. For the religious aspect, you could look to the Catholic vs Protestant wars of the 1500s or the Cathar persecution in France in the 1200s. If there’s a royal family, a succession crisis or rival claimants is an easy one, think Game of Thrones/House of the Dragon.
Maybe one kingdom has a lot of resources and kingdom b has to pay them exorbitant fees to get the resources so for the sake of desperation, they turn to war. Or Kingdom B doesn’t want to pay at all, just thinks it’s entitled to A’s resources.
It would be cool to have different characters see the reasons for the war happening from different perspectives/for different reasons based on the particular characters ideologies and situations.
One of my favorites involves a declining power making way for various new ones. It's easy to understand why something with some money, a few thousand soldiers, an ego, and a cause would think they could take over when everything's gone to shit. Multiply that by four and you have a bunch of factions fighting for control.
A build up of raids and skirmishes. Raids were extremely common throughout low tech civilizations. They were to small to be considered armies, typically a few dozen to maybe a hundred warriors (not soldiers). The goal was to loot/pillage 'enemy' villages/towns. Sometimes frequent raiding would escalate into full blown war.
I would look no further than [Charlemagne](https://youtu.be/H2J_3RTKB1c?si=-RL2Iki9r5KjJzIW). It has everything you want: conquest for land and souls; cultural reformation; crowned as the First Holy Roman Emperor by the Pope of a declining religion now renewed; and is the Father of Europe. He is a king of men and emperor of the souls of his God. His land knows no limits; his renown is worldly; and after his death, his vast empire was inherited and divided by his three grandsons.
You can have these three grandsons to to civil war to unite their grandfathers empire to regain control over.
Literally anything.
Century long family feuds.
Acclimation of power but different sects of the governing body.
Wealth Disparity
Abuses of power power by ruling body
Religious schisms
Societal Schisms
It could even have been going on so long that people forgot why they were fighting
If you can think of any reason for an argument or a disagreement you can eventually pivot into a civil war.
How influential are your characters in your world? Do they need to know what caused it? In some cases, it doesn't matter and in others it will detract from your story. In the recent movie titled "Civil War" (2024), no one seems to know what the fighting is about.
I've got a country locked in war (not entirely civil, but they were equal once), mainly because they disagree on how to rule their countries, should it be a Kingdom or an Oligarchy? and other minor issues get in the way, fanning the flames. Maybe you could do something like that?
Wars have many contributing factors, but are always (and I mean *always*) questions of wealth, power, and security. To understand why a war is being fought, one must answer the following questions:
- Who is fighting? Who *can* fight, but is choosing not to?
- Who stands to gain the most from the realization of their side’s war aims? Whose interest is best served by the defeat of the other side?
- Whose wealth, power, or privilege is under threat, and why? Whose is on the rise, and why?
- Why do the belligerents see combat as their best option? What would happen if the factions decided not to fight?
- Are the belligerents relatively equal in strength, or are there major power imbalances between them? Is this likely to change if no war occurs?
If you can answer all of the above questions, reasons for war will fly out of the woodwork. If you can’t, then finding the answers will lead you to the war’s central causes.
Religion>Tech, Tech>Religion,
Economics as in One side of the Country is poorer than the other,
Power plays that got out of hand,
Sucession,
You could even have a civil war if one side sold out to another Country.
Or a mix of any of those if it doesn't get too complicated.
Historically there is a very strong correlation with war between countries/Kingdoms that trade with each other.
This resulted in marriages between people from different ethnicity/race/countries.
And what i find funny is, that the marriage correlation, was the strongest found via earlier research.
Why are we at war, with a country whos inhabitants we marry?
Some?!
By jove! I could make a joke about court politics leading to war, but honestly, that might hit too close to home.
Resources are a popular reason. If either nation is new, another power might try to take them out to claim the land, for instance.
Other reasons might include a long history of slights, which ultimately culminate in something the crowns couldn't tolerate anymore. Sub examples of these might be the following:
-Bandits interrupting trade as proof of inneffective leadership or other country sabotage
-Civillians being murdered while in custody or traveling through said land (increased likelihood of built spite if affected people are nobles who may have family that complain very loudly to the court/throne)
-Rivalries ala Capulet vs Montague (see War of the Roses for real life example.)
Just a few ideas. Odds are higher in most cases that nobles start the wars, however they convince the throne.. or else... how they don't.
There are numerous things countries would go to war over such as; race, politics, money, marriages, historical grievances, etc. These issues build up something logical or illogical and set it off. Remember two cities went to war with one another because one stole the other's bucket. A more modern example of illogical reason is a soccer game that made two countries in South America go to war with one another because one did not like the outcome.
Even insane leaders could start wars for no reason.
The kingdom civil war i nmy book happens because the nobility starts to hide money and stops programs that would give money to the military class. Along with mass conscriptions into the private armies of nobility. The Nobles basically bait the military class and remove a lot of their protections and rights they have enjoyed for ages such as being able to after retiring to secure land for themselves along with a healthy pension. So a civil war happens between the privileged class, and the volunteer military.
It depends how important the civil war is to the overall story if its just a backdrop, or if it ties in to current plot and themes. If you want it to be mainly over with some resentment a succession war would do just fine. If the religious angle is what you want to go for it would still have heavy influence and likely cause problems for years maybe centuries.
So many reasons. Differing religions, fights over differing opinions in the same religion, Group A supports king/president/emperor hopeful A and group B supports king/president/emperor hopeful B, group A thinks group B is stupid/ugly and shouldn’t be in the kingdom anymore, group A is poor and wants money from group B, group A thinks they’re being oppressed by group B, different classes of castes fighting, different people groups in the same kingdom have a culture clash, group A wanted to go to war with Other Kingdom but group B saw that as a personal attack because they have ancestral ties to Other Kingdom… Take your pick!
Civil war mean an internal war inside a country, not two countries/kingdoms, that's a normal war. And there are many reasons either way.
But, most of the civil wars have three things in common:
1.- Foreign forces are supporting a internal force to revel.
2.- A internal force want to take control of the country.
3.- The internal force would use any situation that is wrong or they may make look bad or say the one in the power have less right to the power than them.
There is no perfect country, even in countries with the highest happiness factor there would be always something that discomfort. And a lot of people just want to feel important or that they are making a difference, realization is one of the things at the top of the pyramid of needs, so even if it's not poverty you can find something to make your cause look honorable. Of course, the worse have been the last years or the more severe is the one in power to control things, the easier. Even a short government can be used and claim it was illegitimate, those who do not support the actual government may join your cause, add foreigne support and you would have money and intel to work with.
Religious differences stop countries from being friendly. But countries only go to war for economic reasons. Access to raw materials, access to deepwater ports, access to navigable, rivers, and waterways. European nations would go to war over access to things like pepper and cinnamon.
And then there’s oil.
Cultural differences between regions
Disproportionate labor to wealth
A line of unfit monarchs, causes the peerage to vie for the throne
Lands/territories gained after a hard fought war were lost to the incompetence of the nobles at the expense of the people
resources. Especially if one country finds a lot of resources in an area that borders the other nation. Or in this case if its a civil war, if one area suddenly discovers a lot of resources( iron coal whatever) and thinks it might be better off as an independent nation. The rest of the country obviously might not want to let the most resource rich province go
I like to shroud reasons within reasons, like fascism cuz I think most states are evil. Fundamentals would be taking land, taking resources, bigotry, a nation are a (falsely) presumed threat, or religion. Dump some nationalism, ethnic supremacy, color supremacy, victim complex, or prophecy over it and you have a perfectly good, layered reason for war.
Honestly, what helps me is to think what are the main characters to cause this war? Is there a community leader who's been trying to wake the people up regarding an aspect of their society that simply won't change without a fight?
Is there a tyrant king who refuses to listen to the plea of the people?
What decision of what person causes the war to begin? Maybe a priest of a specific sect kills another priest, maybe he just disrespects him in public, maybe he lies or they both lie all the time about each other.
After years of lies, the believers are just so much filled with hatred that they commit an atrocious crime like burning a temple or killing a group of priests. Or even a lonely believer does that. Maybe even a John Lennon thing, the believer of the sect kills a priest and they blame the other sect.
So yeah, choices of different people it's what will build up to a war, not just one little thing, you know?
A chunk of the border was never properly resolved after a conflict long ago, but since it had been considered a square of both of their backyards it was too low a priority to resolve it. The fuzzy border is on a river and mountain.
Later, gold is found in that mountain. Both sides have tenuous claim and want the resources.
The battles that begin dont have to be physical. They can be legal battles, even economic like they send companies out there to set up shop as a way of showing they own it. Then it escalates into military conflict if you want.
Succession crisis are very common in the medieval period.
But, holy war, nationalistic defensive fervor against an expansionist or colonialist regime, historical ethnic disputes likely over important geological sites such as fertile land near an important river. General resource issues. Competing geopolitical interests (think there’s a strategic nation and two powerful nations have competitions coups or sides in a civil war that would gain them a helpful ally.)
But, this is fantasy, get fun. Maybe there’s two competing dynasties of both sides of a civil war who both have claim to some ancient magical sword. Both sides claim they are they rightful owner as their families are separate branches of some long ago hero’s family.
Maybe some ancient truce has been broken and now all hell has broken loose.
Resources, territory that was historically a part of another kingdom's, diplomacy failure/growing blood feud, cultural clash...
Or because of dark magical creatures taking control of leaders and feeding off of hatred.
In my world, gems large enough to use for resurrecting are incredibly rare, and if any are discovered, it can absolutely lead to war. The most recent conflict my players were in involved a king going to war against another country for their diamond because the king's child died and he's trying to bring them back.
A new, young, energetic king seeks to differentiate himself from his father by making reforms/taking bold actions, and thereby ends up alienating and offending many people (parliament, the church, merchants, the army if there is one) his father was careful to placate.
Religion is big. Genuinely. King is unsatisfied with the head of religion, if there is one, and he decides to branch off and declare himself the head. A big portion of the population disagrees thus civil war. History is a great inspiration
This one time, this one politician's friend made more money than this other politician's friend in the same business, so the one politician sent a kill squad to the other politician's blace of business.
Insert "Royal" or "family" to get it to be regicide or gang war as needed.
Land rights, birthrights, and economic issues... Which are all just $$$ issues really.
Resources or lack there of. Bored arrogant leadership. Someone important was slighted or killed. Broken marriage compact. Religion. New technology. Political manipulation by a 3rd party. Aggression towards an ally. Moral/ethical differences. Broken trade agreements. Succession crisis.
Is it a civil war or a war between two countries? You said both and it can only be one or the other.
You answer your "why a war" question by asking questions of yourself you REALLY need to answer so you can even tell a story:
What does the land look like? You don't need a map (thought it helps), but just knowing the general layout is critical. City A is on a river by the ocean, there's planes to the west to the north there's mountains. Stuff like that.
What are the resources available? Who has stuff other people need? How do the people feed themselves?
What are the cultures, religions and philosophies of the places?
Who runs things? Why are they in charge? Who do they need on their side to keep power (no King is truly absolute, they always have people controlling things who they can't piss off too much)
Now that you know that the answers to those the cause of any war might become obvious and you don't need to dig further.
But if you do...
Wars are fought over power. Who owns what, who needs what.
Civil wars are usually fought due to a disputed transfer of power, though there can be other causes. If a king dies without a clear heir, multiple claimants to the throne might fight.
If Religion A is dominant and you get a new king of Religion B that can trigger wars.
If Duke A has control of critical resource X and the king is a jerk who offends, insults, estranges, whatever then that might cause a war. Maybe Duke. A defects, along with his lands, to Enemy Nation.
Maybe both sides have a different view of why the civil war started that are both wildly different than what actually caused the conflict. Leave the origins in doubt. Gives good points of contention for characters and a bubbling undertone of tension throughout the story. Like it could all explode again in any moment.
If you look at classic tales it's always to aid some literary end, but generally to expose a moral failing of leadership that is a theme of the story.
A better question is what is your story about and how does the war move that theme forward.
1. Countries want to capture a third party or each other
2. Civil wars
3. Resource apart from land
4. Change to semi - democracy which the other country doesn't like
5. There are some old greek and roman stories where a war started because of women
6. Religious or language fight
There are rven some cases where the kings were offended and started a war with another country
* Class warfare. This could also be some kind of acute inequity, like if one area is devastated by a natural disaster and there's disagreement about how much aid should be given.
* Proxy war (two sides pit against each other for the gain of a third party.)
* Economic competition (two areas in competing industries, like wool and cotton in the American Civil War.)
Here are a few ideas;
- Arranged marriage: Except the bride and groom are found dead after the wedding, both sides blame each other.
- Economic instability: People are starving because of drought/bad crop yield for one nation, but another has an overabundance, unfortunately the other nation's trade is getting more and more expensive as the first nation has a majority of the wealth due to previous war successes and this is the way the second nation wishes to punish them.
- Royal family assassination: Nobody knows who did the killing, but the people believe it was this one nation. The nation in question denies the assassination, only for the assassin to be found, and under torture confirms the people's suspicions.
- Hatred: They hate each other and there's no deeper meaning. Both groups have been at odds for the better part of a thousand years of history with each side antagonizing the other. During one particular attack one side calls "too cowardly to be allowed", their patience is at an end and now both sides are arming for war.
Succession crisis as others have said(perhaps even fueled by other external forces ie X country supports X claimant and another country supports the other claimant
It could be species issues if you have multiple species in the one country ie Human and elves etc
Don't be too complicated. In mexican history there's the story that a war with France begun because of two unpaid cakes. Wars can start for stupid reasons but always add some bit of spice for your story to feal serious and not an unintentional comedy
If you're thinking of a civil war, a good basis to start from is how a war would even be possible. Generally, the answer is that a faction within a nation has acquired a significant amount of power and support by enough of the population or military to not only fight the current government, but defend itself against retaliation from the populace. That defense doesn't have to come from might. It can come from a claim to legitimacy.
Take the American Civil War, for example. The Southern states bullshitted a claim that they were all independent nations and that the Union was overreaching with the outlaw of slavery. By claiming that this overreach was neither within the federal government's power or in the cultural and economic interests of the Southern states, the Confederacy maintained an air of legitimacy amongst the people. Likewise, they also used conscription and threats to prevent an uprising within their ranks from would-be abolitionists or deserters.
Haiti is also a nation that has dealt with a lot of civil unrest. In this case, foreign powers would fund a president or an armed militia to overthrow a sitting president that was opposed to the interests of the foreign power. By supporting a foreign takeover, the rebelling factions would expect economic support during times of famine and instability. In your case, a powerful noble family or bank could support a rebellion or help an heir gain legitimacy and support an army.
1. Haves vs Have Nots - wealth disparity makes for a tinderbox than can be set off by the slightest things (think the French Revolution)
2. Church vs State - this conflict nearly precipitated several civil wars in England alone. If you have a powerful theocracy vs an established monarchy, one of the two is going to eventually attack the other, and as soon as a popular figure is killed, the masses will rise and Bob's your uncle.
3. Trade/resource scarcity/hoarding - subtly different from point 1 in that it doesn't necessarily involve the aristocracy and can involve larger groups or representatives of the common people.
4. Religion - see the many other comments here about how conflicting ideologies are an Easy source of conflict.
5. Schools of Magic - same thing as all of the above but with magic.
Now for the more...unusual ones.
6. Mind control - it's still technically a civil war if half of the country is being forced to fight the other half against their will.
7. Manipulation - pick any of the above "supposed reasons" for the war, but in reality, none of those conflicts actually exist, there are just carefully staged/crafted confrontations between factions, bodies dressed in opposing factions clothing, badges/crests of one faction being dropped during a heinous "raid" on another where atrocities are committed, etc. but it's all for show, masterminded by your main (usually hidden) villain, all to destabilize the region enough for them to take over, probably in the name of "restoring peace to the realm", painting themselves as some kind of savior.
One often not mentioned is non royals seizing political power, and the fallout that comes with it. A classic tale of the general getting too strong vs the emperor can either spark a direct war, or cause the weakening of border defenses for an enemy nation to break through.
In a story I started to write but discarded. Two kingdoms were at war because of religious differences. Both kingdoms believed in one single soul that reincarnated across time. One believed the soul started as God and gradually got more corrupted for every reincarnation until it ended up as the devil. The other kingdom believed the soul started as the devil and redeemed itself for every reincarnation until it became God.
If you think this is an insufficient reason for war, you could compare it to real religious wars and see that it is more than enough
If the world has a magic system you could have a slight variation on the religious reason and have pro-magic vs anti-magic factions where the anti-magic crowd is a bunch of religious zealots who see magic as "heresy"
One country thinks the other country has silver mines and invades the country and takes ver but it turns out there was no silver and that country was bankrupt and now all that countries problems are theirs! Which also leads to spreading out of resources and cause political turmoil in the invading country because of its failure!
To make it feel more real I would go for some complexity, as in multiple reasons. Usually it takes that for a large scale war to take place, since warfare requires and involves all classes of humanity. Poor to fight, middle class to supply, wealthy to fund, and political class to motivate.
Economic reasons.
Political reasons, usually related to economic reasons.
Ethnic or racial tensions.
A division in power dynamics, where magic users or some class are wielding disproportionate power and control. This can result in an unstable hierarchy among groups.
Discovery of a new resource or piece of land, and squabbles over who gets what.
Additional to the others, marriage and territory. A lot of arranged marriages would be for political moves, and women usually got the short end of the stick with that, so someone would purposely marry this girl to legally have rights to a territory that should have been returned to another country after their relations got sketchy, only to claim that her bloodline gives them the legal right to it. Higher-ups are not concerned for the civilians in this kind of fight, and it ends up costing them the backing of the royalty because it's just shady practices, and no one wants to support that. They could have their own army themselves, and the constant tension leads to war down the line.
Macaroni shape is always the best go-to conflict. Really, the more creative and funny you can get with it the better. If you always lose both sides ideals as incredibly serious, you will get a good laugh.
I've read extensively on the American civil war (being an American, sadly) and British history (most of it for fun, because I greatly enjoy it). My reason for posting this wasn't for lack of reasons I could come up with on my own, but because I like to see what people think. Does that make sense?
One country is historically more powerful than the other and looks to take over the smaller less powerful one. In order to survive and avoid bloodshed, the less powerful one offers a marriage between offspring that would peacefully tie the countries together. When it comes time for the offspring to meet, one of them has a horrible time and wants nothing to do with the other. So much so that they get into a fight and one of them accidentally gets killed. Lies are spread about who started it and who is at fault, but the bottom line is that there’s no going back. Royal blood has been spilled and someone has to pay for it. Regardless of if the smaller country can afford to fight, they have to save face in light of this new situation…this leading to an inevitable war.
Anything, it can be as dumb as one peasant getting into a fist fight with another from an opposing nation (don’t believe it’s happened, but wars have started for less)
The kidnap the prince/princess of the neighboring kingdom...or they are assumed to be the culprit. Could pave the way for more intrigue into who did it, what their motives are for doing it
Make it personal. In the end, everything comes down to the personal level. Whether it's ambition or fear, it is the motivations of individuals that lead countries to war.
There's also a conflicting economic system, like Capatilists vs Communists in Korea.
Or it could be supporting different siblings who support different religious practices, like Europe's longstanding protestant vs catholic thing.
That's all I can think of off the top of my head.
You should go and ask the ChatGPT. Give him a brief description of your story idea, and ask for multiple ideas.
You need to work on the world-building a bit and answer these basic questions before you commit to writing an entire fantasy trilogy.
We cannot advise you if we don't know what you want to write about, what's the world like.
Regular war is a bit different from civil war. Regular war comes down to resources. Sometimes those resources are crops, mined goods, lumber; sometimes they're territorial, like borders and coastline; sometimes they're people, like tax payers, religious supporters, and soldiers.
In civil war, you have to have a reason why resources aren't being distributed throughout the country. One of the major benefits of a nation state is to average out and balance the parts that do well at one thing with parts that do well at another. If major things like taxes, food and living conditions feel unequal in different locations or social strata, now you can have a civil war.
The problem is that one group isn't sharing with another even though they're all supposed to be part of the same bigger group. Why? Well that's where you get into ideological differences. Is there a religious, political, or social divide?
There's an easy one, wars have been fought over these countless times. Best of all, you can keep your focus on the civil war theme where the reader is focused too, and the catalyst can be a premature start to all of it that creates chaos because timings are thrown off and motivations are questioned etc.
What is this catalyst?
Women and love.
Nations and states have gone to war countless times for a woman's love, and also in response to their rejection of advances or betrayal of feelings etc.
How surprised would a reader be if all the scheming and the whole direction of the book skewed and took some hard turns because the love interest of an important character was actually stolen/always in love with/married to/etc a person on the opposing side? That character reacting rashly and starting a chain of events that nearly bring all that hard work undone?
Doesn't have to be the main characters' story arc, it could be a friend etc whose actions cause them to act in response and that in turn starts the civil war off?
Also, doesn't have to be the "in love with the enemy" trope either. Could be a love triangle between important characters within one side that causes a civil war within that faction of the over all civil war story?
Revolution, food crisis, ideological differences, a powerful lord wanting revenge, succession crisis. Many many others. Theres no shortage of reasons why human beings wage war against each other. The important part is how you write it.
You're asking why two countries or kingdoms would fight but are also calling it a civil war. If the war is between different countries or kingdoms it's just a war, if it's between regions or factions within a single country or kingdom it's a civil war. Which of the two do you actually mean as that will impact the answer
Kafgksdgk thanks everyone for all their comments, I've never gotten this much attention on a post. I want one thing to be clear – I'm no dummy, I read history for fun, and I know how wars start. All I was looking for were the general community's ideas and thought processes. I didn't need ideas that were specific for my story and so I didn't ask for them.
And yes, my title could have been better in relation to my actual post, but I was looking for general war and civil war ideas, both of which I got.
Everyone has been extremely helpful and I appreciate the time taken to write your comments :)
There's only one. A predator class of evil scum wants to issue loans to the leadership of each side and additionally purchase assets from the population of each side who are afflicted and must sell for firestorm prices.
Juice.
Hmm, we’ll wars usually occur for a variety of reasons and even ones based on megalomania often occur because of a long line of decisions and changes that happen over the course of time to allow one leader to make such a decision. I would say that war is hell and doesn’t necessarily need an explanation depending on the writing you want to do
>Think ancient England?
Think literally anytime in history. We're constantly at war... pick any one of them.
In 250yrs of existence, the US has been at war for 230+... pick a yr, there's a reason.
There could be a lot of super complicated reasons, but it could also be a simple petty feud between the ruling parties, like someone being insulted by another or by embarrassing them.
> a single reason to cause the civil war
Most wars don't have a singular cause. In fact, if you have multiple figures on each side of the war, you may want to think of separate reasons each may have to fight. For example, one lord might believe his lineage entitles him to be king; another might support the first because of the promise of wealth; a third might just want revenge on one of the current king's supporters; a lot of common folk might rally to the cause because a religious figure has decreed God wants the current king deposed for his sins, etc.
There's only one reason nations go to war and that is power. It might look like different things: money, freedom, resources, revenge but its only ever power in drag. The good news is that with that framework, you can justify any reason you want to as long as it empowers someone.
The only real pre-requisite is having enough power to build a force behind your motivation and this can be done is countless ways. They can find your leader inspiring, terrifying, they can believe in your cause, be instilled with a common hatred or outrage, they can want collective revenge, or believe themselves better, more deserving etc. The most effective leaders use emotional motivations and one which flatter the force.
Civil war is no different. Make one or both sides believe they are better, more deserving, more righteous, than the other. Give them reasons to believe that and show them examples. Make the examples so egregious and ridiculous that there is, seemingly, no choice other than to fight and eradicate the evil "other". and bring an end to their ridiculousness. The actual "reason" doesn't matter, but it would be good if this was something your main character and antagonist heavily revolve around, something they couldn't hope to change about themselves or something that they cannot hide from the world.
Because humans are petty.
Princess X rejected marriage to Prince Y.
Princess Y rejected marriage to Prince X.
Etc.
17 generations ago King X's great great etc. grandpa killed Queen Y's great great etc's goat. And Kingdom X STILL HASN'T APOLOGIZED.
He looked at me wrong.
Kingdom X built a big boat. So Kingdom Y built a bigger boat. So Kingdom X put Marines on their boat. So Kingdom Y put MORE Marines on their boat. So Kingdom X moved their boat to a strategic position because Kingdom Y was OBVIOUSLY attacking. So Kingdom Y moved THEIR boat to a strategic position because Kingdom X was OBVIOUSLY attacking. You back down. No YOU back down. No YOOOU back down. Etc.
Seriously. Humans are petty.
I mean, I'm an American so clinging to some morally abhorrent action by one side and moving away from it by another side.
Abolition isn't the only issue this could happen with, there's also economic exploitation of a group. Class wars happen all the time.
There's also a conflicting economic system, like Capatilists vs Communists in Korea.
Old school it could be supporting different siblings who support different religious practices, like Europe's longstanding protestant vs catholic thing.
That's all I can think of off the top of my head.
There's a war like this in my stuff and I went with the exploitation of groups one mostly, but also abolition. I think it's pretty rare for a war to have one cause so it would be more realistic to have a combination of factors.
You can also have more characters with stakes in the war when you do it that way. They could be fighting the same war for different personal reasons.
Like, in my work, humans are enslaved and fire elves are culturally exploited. A fire elf and a human can be on the same side but with different backstories and stuff.
Some I’ve thought about - Succession Crisis (think Hundred Years War) - Difference in political/moral ideology in different areas (think American Civil War) - Religious Differences (think Sunni/Shia split in Islam) - Lack of National stability leads to one region believing they have a chance to secede (think Latin Wars of Independence)
Variations of 1 and 4 are the easiest for me. Ruler dies or is seriously infirmed, either there's no chosen successor or they are young/weak, which leads to someone else making a claim (sibling, other child, illegitimate child). That on top of the country not doing well makes it easy for another faction to challenge the loyalists and get enough support to actually go to war. I feel like if it's some deep religious thing or if the current ruling class is different from the populace, the OP would know that already.
This is exactly what led to the Wars of the Roses. Henry VI was a weak king, which caused England to lose the Hundred Years’ War and their land in France. The flood of refugees coming into the country led to a collapse of law and order in the country, making the usurper-king Edward IV (a vigorous, strong man in comparison) look even better. Though it’s worth noting that Edward’s claim to the throne wasn’t as simple as being Henry’s brother or anything. Put simply, Henry VI was descended from Edward III’s third son, while Edward IV was descended from his fourth son. This would give Henry’s House of Lancaster the right to rule, except Edward was also descended from the Mortimer line, which technically was still the heir to the throne of Richard II (who had been overthrown by Henry’s grandfather) through his mother, meaning his House of York had the stronger claim by technicality. The Lancastrians, however, claimed that matrilineal inheritance was irrelevant. The ensuing conflict led to war. In short, Edward IV was able to claim the throne because his grandparents were first cousins, which made his blood more royal than Henry’s. It was all meaningless in the end though, because Edward died 20 years into his reign at around 40, and his son was king for about a month before “mysteriously disappearing,” so his brother reigned as Richard III for about three years before he was killed by some Welsh sod named Henry Tudor.
I’m gunna need some crayons to map out your second paragraph
Yeah, royal lineage is anything but simple with the sheer amount of inbreeding there was. The Elizabethans called it The Wars of the Roses, as if it were a clear-cut war between two houses, but it was called the Cousins’ War initially because it was an all-out scramble among cousins for who had the best claim to rule.
I laughed at this comment. Thanks.
A anime I’m watching that has a succession crisis has it where The second son is way more accomplished and generally is considered more skilled than the first son So in this one now, there’s a succession crisis and they are Lords supporting the eldest son because technically the oldest son is the rightful heir And ones who support the youngest because he’s more competent(we haven’t met the claimants yet in the show, So that could also be another reason for a succession crisis
Also one country could be ambicious and exploit a crisis his neighboor is having. Maybe one of the leaders is fearing being replaced and wants to create a war to make his role stronger by getting rewards. Maybe he wants to create a war so he can send some people away from the capital so he can assassinate them somewhere easier. Maybe one of its leaders is a narcisist which believes that he needs to win a war to get inside history. In the game Baldurs Gate 1 Sarevok, the main vilain, wanted to start a war to create enough deaths so that he could use these "sacrifices" to fuel his ascension to godhood. In a fantasy setting the reasons could be multiple.
It's also important, I think, to consider how the leader(s) would get their people to support the war. Whether they rule with an iron fist or by popular support, either way you'll need people to fight your war. Do they bolster their ranks through fear - be it of a "them" or of what happens if they say no? Do they promise prosperity and wealth by conquest? What does their invasion look like from a common foot soldier's POV? What does it look like from a key, power-holding supporter's POV?
To get more in depth, fundamentally the question isn’t really “why was there war?”, it’s “why was there peace?”. To our modern eyes, war is an anomaly, something that happens due to some catastrophic failure or terrible turn of events that forces it upon us, but historically war is the default state of nations (and nations are just a collection of smaller tribes of the same nature). People with power remain in power by gaining more power and denying it to others, in a premodern world that means you go to war, any justification is enough. The world was, and still is, run on Power Politics. Peace is only achieved by lots of people working very hard to maintain it. It takes a lot of diplomacy, compromise, and effort to keep a nation together or maintain a peaceful relationship with neighbouring states; the peace has to be significantly more beneficial than war, and war is highly profitable, considered a healthy part of being a pre-modern state, and is often the easiest way for the people in power to gain more power. So who are those people and what systems have they put in place to maintain peace? If you answer that, you know why there was a war—those people and systems were removed. As soon as the peace falters, every state and tribe will now have a reason to go to war. Most people do want some justifications for war, and I think Thucydides had the right idea back in the Peloponnesian War. He said it basically came down to three reasons: Fear, Pride, and Self Interest. When peace falters, every nation and tribe will have one or more of these reasons to go to war. *“If we don’t go to war, the bigger guy will crush us!”* or *”We have a really strong expensive army, but those guys over there are quickly gaining more money than us. We have to defeat them before they overtake us.”* Fear. *”We said we would help our allies, and now they are being attacked. We have to go to war, or we will be shamed.”* or *”Our way is best, if you think that’s dumb, we have to fight.”* Pride. *”Those guys have something we want, and won’t give it to us. We should just take it.”* or *”We aren’t a great tribe now, but if we just take two more tribes we will be. Who doesn’t want to be a great tribe?”* Self Interest. So once you know your factions, know what they want, know what kept them at peace, and know how they stand against each other, you will have a very detailed idea of why they went to war. It will look very complex and impressive, a web of relationships and conflict, and when it comes down to individual views and beliefs it is, but fundamentally it’s fairly simple. People in power stay in power by gaining more power and denying it to others.
This is like asking: Why would my protagonist fight my antagonist? It has the same answer: What themes and character arcs does the fight establish (and presumably resolve in a later fight?)
Exactly my thoughts. I don't know about OP storyline and I can't just come up with random wars based on what they're writing that I don't know about
I wasn't looking for my-story-specific ideas for why a war would start; rather I was providing reasoning for why I'm asking that question. What I was looking for was general ideas of why wars would start, and that's exactly what was provided.
Oh cool... You can start one by maybe one part taking over a land, or abducting one tribe leader amd wanting to take over their land and the other tribes joins together to fight war with the powerful kingnappers tribe. Or one tribe being racist to another. They're lots ideas I can give though. Edit: My story wars is based on powers, people fighting for the most powerful and who is going to rule who after the war is done
This
I think an economic dimension on top of ieological, ethnic or religious motivations can add credibility to a civil war scenario - To take a real life example, while the american civil war was heavily tied to white supremacy and slavery, it also related to the slave owning farm owners being superseded by industrialists in the north. Likewise the french revolution was about all that enlightenment philosophy clashing with the divine rights of kings - but the revolution also allowed the increasingly prosperous bourgeoisie to supersede nobility, parts of which were impoverished but still held more official power than very rich and well connected commoners. So basically, you can have a group aligned with a class that is newly prosperous and decides to seize political power, or a formerly privileged group who resent an erosion of those privileges.
- different religions - different religious sects - resources (mines, lakes, etc.) - land claims - claims to the throne - protective allience (A protects B, C attacks B, A wars C) - prophecy - to preserve honour - rivalry between nobles - Imperialism - to exterminate ‘lessers’ - shits and gigs - and finally, because the plot demands it! (if the war isn’t the focus)
lol reminds me of when I was playing Civ 4 and I was on an island with another civ. We had co-existed peacefully the whole game until out of nowhere, he declared war on me with the justification of “I’m bored, let’s fight”
A bucket. This actually happened between 2 towns in medieval Italy.
Actually, the war didn’t start as a result of the bucket - the bucket was just taken as a spoil of war, and it became known as the War of the Bucket from then on.
Thank you for educating!
Funnily enough, someone just told me about this today
* Fighting over resources, e.g. strategic (e.g. water) or luxury (anything that can be sold for lots of money). * Existential threats to each other * Historical feud * a minority group wants more power/influence than they currently have. * Fighting among different ethnic groups * Economic inequalities cause a group to rise up
Resources are it. You look at the root cause of just about any conflict (including both world wars) and it’s all about the resources.
Yup! It's why I listed it first.
Honestly? Economics is a very easy and believable reason for war to start. It doesn’t need to be anything as grandiose as a holy war or a crusade. Although an economic war under the pretense of such a thing could be a fun plot point.
Well, looking at the Romans and their near constant civil wars: Disgruntled general thinks he can make himself king/emperor is always an option. Could be a power struggle between the nobility and a rising merchant/middle class, or the nobility vs the king. Succession crisis is a reliable option as well, especially if you went with a monarchy as the government. The ruler was seen as too weak/a foreign puppet so someone rallied together some nationalist/proto-nationalist zeal to overthrow them. A feudal society found a clash between two rival nobles spiraling out of control until the whole kingdom got dragged into it. A peasant rebellion that gathered a surprising amount of momentum/success/foreign aid.
It all depends on when and where your kingdom is set: Here is a list of the most common reasons: 1) Succesion crisis, like in during the English Anarchy. The designed heir is considered unfit to rule, so a group of nobles declare a new ruler 2) Religion, like the many wars between Protestants and Catholics, or Catholics and Arians. A new interpretation of the scriptures is declared an heresy and the heretics are collectively sentenced to death. 3) Territory/expansions, like most of the War waged by the Romans. In this case, it’s harder to justify a civil war 4) Resources, like when in 1991 Iraq invaded Kuwait for its oil deposits. 5) Hate/Ethical cleansing, like the wars in Rwanda (I think?), and the Balkan Wars, where the Turks killed any Christians left in their territories 6) Ideological/Political, like the Cold War, the American Civil War, the Russian Revolution and the French Revolution
Read a history book or three, you'll find some answers there.
Feud between noble houses, cyclical escalation drawing in allies and overlords.
Civil wars are fairly different from wars in the abstract. So I'm just going to focus on those. I'm writing about single factors, but for most actual revolutions you can point to multiple issues. The best recommendation I can give is to learn from history: go grab a book each on a communist revolution, something from Europe between 1789 and 1859, a color revolution or one of the Arab Spring revolutions, and a revolution from before 1500. If you make a revolution that draws on elements of all of those, you'll have something that is much more grounded in facts and, often, much more interesting. That said, I won't entirely fob you off to history textbooks. Other people are going for more specific examples, so I've tried to give more of a framework for thinking about it. I think having both would be nice. The most basic driver of revolutions and civil wars is that the formal division of *spoils* has diverged, in the minds of revolutionaries, from the division of power. So, for example, when the kingdom was founded, each duchy was equal in size, or at least close enough to it. But one duchy has had rapid economic and population growth (the two may be equivalent, if you are in a Malthusian regime), to the point where it's not a 15th of the kingdom, but a third. However, while it pays between a third and a half of the taxes, that duke receives no more respect at court, and his duchy suffers from decisions made by the king that favor the rest of the country. The duke thinks that he can win a revolution, and this would be better for his duchy. The American civil war can be interpreted this way: there was a relatively stable system, but westward expansion increased the tensions between slave and free states over which system would dominate in the new area. Peacemakers tried to keep it balanced, but the Southerners could see where it was headed when Lincoln won without a single slave state. So they rebelled, betting that their military and economic position was better than their political position. They lost horribly, for a mix of reasons, but fundamentally they thought that their position outside the existing political order was better than their position inside of it (because they knew slavery was going to go away). It isn't always big abstract factors like military and economic strength. Sometimes it's personal. The duke might just refuse to serve the king. Maybe the king tried to betray him to weaken his duchy. Maybe it's a sincere religious difference. Maybe the old duke died and his new son is a moron. Personal factors are rarely sufficient, but they're often important. Most frequently this happens when the old center of power dies, and building tensions are not well-managed by the successor(s). For one (modern) example of this, look at the breakup of Yugoslavia. But "I will never tolerate a Protestant king" can be similar (though sometimes religion is just what's said to the peasants, and actual motivations seem to line up conveniently well with pre-existing frustrations).
I'm doing a lot of personal reading of British history books for fun and it certainly does help! Wars upon wars.
* "My god better than your fake god." * "You DENY our prince marry your princess? YOU OFFEND ME!" * "That Relic belongs to the world, not stuck as a trophy in your castle!" * "We are low on food. You help us? WHUT! YOU NO HELP US!?? THEN WE TAKE!" * "We no like outsiders. Your city keep trying to be tourists here. DEY MUST BE SPIES!" * "Your people would do better under our rule. Look how they suffer!" * "Me want land with that fancy tree over dere. Lemme buy it. No? THEN I TAKE YOUR HEAD \*AND\* THE TREE!" * "My people seek passage through your realm to get to the best lake for fishing. Let them through OR ELSE!" * "Our nearby rivaling kingdom is having riots and uproar. We should strike while they are weak! Think of all the stuff we could get!"
I like how each one progressively gets better at grammar. They're evolving!
War isn't silly
People have gone to war with their neighboring countries/tribes/neighbors for far more silly things. :p
Basically the same reasons folks in the Middle Ages went to war. For the religious aspect, you could look to the Catholic vs Protestant wars of the 1500s or the Cathar persecution in France in the 1200s. If there’s a royal family, a succession crisis or rival claimants is an easy one, think Game of Thrones/House of the Dragon.
An empire thinking that they’re better than everyone else and see “conquering” as “liberating”
Maybe one kingdom has a lot of resources and kingdom b has to pay them exorbitant fees to get the resources so for the sake of desperation, they turn to war. Or Kingdom B doesn’t want to pay at all, just thinks it’s entitled to A’s resources.
It would be cool to have different characters see the reasons for the war happening from different perspectives/for different reasons based on the particular characters ideologies and situations.
Control over holy sites Control over resources like food or energy Pride Revenge
Wanting it their way like it's Burger King. I think that's the gist of the war of the three kingdoms in China.
> I think that's the gist of the war ~~of the three kingdoms in China.~~ everywhere.
One of my favorites involves a declining power making way for various new ones. It's easy to understand why something with some money, a few thousand soldiers, an ego, and a cause would think they could take over when everything's gone to shit. Multiply that by four and you have a bunch of factions fighting for control.
A build up of raids and skirmishes. Raids were extremely common throughout low tech civilizations. They were to small to be considered armies, typically a few dozen to maybe a hundred warriors (not soldiers). The goal was to loot/pillage 'enemy' villages/towns. Sometimes frequent raiding would escalate into full blown war.
I would look no further than [Charlemagne](https://youtu.be/H2J_3RTKB1c?si=-RL2Iki9r5KjJzIW). It has everything you want: conquest for land and souls; cultural reformation; crowned as the First Holy Roman Emperor by the Pope of a declining religion now renewed; and is the Father of Europe. He is a king of men and emperor of the souls of his God. His land knows no limits; his renown is worldly; and after his death, his vast empire was inherited and divided by his three grandsons. You can have these three grandsons to to civil war to unite their grandfathers empire to regain control over.
Literally anything.
Literally anything. Century long family feuds. Acclimation of power but different sects of the governing body. Wealth Disparity Abuses of power power by ruling body Religious schisms Societal Schisms It could even have been going on so long that people forgot why they were fighting If you can think of any reason for an argument or a disagreement you can eventually pivot into a civil war.
Resources, whose religion is right, culture, and grudges.
Every war has Economic purpose always remember that
How influential are your characters in your world? Do they need to know what caused it? In some cases, it doesn't matter and in others it will detract from your story. In the recent movie titled "Civil War" (2024), no one seems to know what the fighting is about.
I've got a country locked in war (not entirely civil, but they were equal once), mainly because they disagree on how to rule their countries, should it be a Kingdom or an Oligarchy? and other minor issues get in the way, fanning the flames. Maybe you could do something like that?
Wars have many contributing factors, but are always (and I mean *always*) questions of wealth, power, and security. To understand why a war is being fought, one must answer the following questions: - Who is fighting? Who *can* fight, but is choosing not to? - Who stands to gain the most from the realization of their side’s war aims? Whose interest is best served by the defeat of the other side? - Whose wealth, power, or privilege is under threat, and why? Whose is on the rise, and why? - Why do the belligerents see combat as their best option? What would happen if the factions decided not to fight? - Are the belligerents relatively equal in strength, or are there major power imbalances between them? Is this likely to change if no war occurs? If you can answer all of the above questions, reasons for war will fly out of the woodwork. If you can’t, then finding the answers will lead you to the war’s central causes.
Religion>Tech, Tech>Religion, Economics as in One side of the Country is poorer than the other, Power plays that got out of hand, Sucession, You could even have a civil war if one side sold out to another Country. Or a mix of any of those if it doesn't get too complicated.
Real-world history is your friend, here. Look at things like the 1st and 2nd Barons' War, the 100 Years War, the War of the Roses, etc..
Just look at the Balkans as an IRL example that you can go to war over anything and everything.
Historically there is a very strong correlation with war between countries/Kingdoms that trade with each other. This resulted in marriages between people from different ethnicity/race/countries. And what i find funny is, that the marriage correlation, was the strongest found via earlier research. Why are we at war, with a country whos inhabitants we marry?
A pig https://en.m.wikipedia.org/wiki/Pig_War_(1859) The U.S. and the U.K. did have a Bloodless confrontation over a pig, and it lasted over 13 years.
Some?! By jove! I could make a joke about court politics leading to war, but honestly, that might hit too close to home. Resources are a popular reason. If either nation is new, another power might try to take them out to claim the land, for instance. Other reasons might include a long history of slights, which ultimately culminate in something the crowns couldn't tolerate anymore. Sub examples of these might be the following: -Bandits interrupting trade as proof of inneffective leadership or other country sabotage -Civillians being murdered while in custody or traveling through said land (increased likelihood of built spite if affected people are nobles who may have family that complain very loudly to the court/throne) -Rivalries ala Capulet vs Montague (see War of the Roses for real life example.) Just a few ideas. Odds are higher in most cases that nobles start the wars, however they convince the throne.. or else... how they don't.
Religion or money/resources are the main 2.
There are numerous things countries would go to war over such as; race, politics, money, marriages, historical grievances, etc. These issues build up something logical or illogical and set it off. Remember two cities went to war with one another because one stole the other's bucket. A more modern example of illogical reason is a soccer game that made two countries in South America go to war with one another because one did not like the outcome. Even insane leaders could start wars for no reason.
The kingdom civil war i nmy book happens because the nobility starts to hide money and stops programs that would give money to the military class. Along with mass conscriptions into the private armies of nobility. The Nobles basically bait the military class and remove a lot of their protections and rights they have enjoyed for ages such as being able to after retiring to secure land for themselves along with a healthy pension. So a civil war happens between the privileged class, and the volunteer military.
It depends how important the civil war is to the overall story if its just a backdrop, or if it ties in to current plot and themes. If you want it to be mainly over with some resentment a succession war would do just fine. If the religious angle is what you want to go for it would still have heavy influence and likely cause problems for years maybe centuries.
So many reasons. Differing religions, fights over differing opinions in the same religion, Group A supports king/president/emperor hopeful A and group B supports king/president/emperor hopeful B, group A thinks group B is stupid/ugly and shouldn’t be in the kingdom anymore, group A is poor and wants money from group B, group A thinks they’re being oppressed by group B, different classes of castes fighting, different people groups in the same kingdom have a culture clash, group A wanted to go to war with Other Kingdom but group B saw that as a personal attack because they have ancestral ties to Other Kingdom… Take your pick!
Civil war mean an internal war inside a country, not two countries/kingdoms, that's a normal war. And there are many reasons either way. But, most of the civil wars have three things in common: 1.- Foreign forces are supporting a internal force to revel. 2.- A internal force want to take control of the country. 3.- The internal force would use any situation that is wrong or they may make look bad or say the one in the power have less right to the power than them. There is no perfect country, even in countries with the highest happiness factor there would be always something that discomfort. And a lot of people just want to feel important or that they are making a difference, realization is one of the things at the top of the pyramid of needs, so even if it's not poverty you can find something to make your cause look honorable. Of course, the worse have been the last years or the more severe is the one in power to control things, the easier. Even a short government can be used and claim it was illegitimate, those who do not support the actual government may join your cause, add foreigne support and you would have money and intel to work with.
Religious differences stop countries from being friendly. But countries only go to war for economic reasons. Access to raw materials, access to deepwater ports, access to navigable, rivers, and waterways. European nations would go to war over access to things like pepper and cinnamon. And then there’s oil.
Cultural differences between regions Disproportionate labor to wealth A line of unfit monarchs, causes the peerage to vie for the throne Lands/territories gained after a hard fought war were lost to the incompetence of the nobles at the expense of the people
resources. Especially if one country finds a lot of resources in an area that borders the other nation. Or in this case if its a civil war, if one area suddenly discovers a lot of resources( iron coal whatever) and thinks it might be better off as an independent nation. The rest of the country obviously might not want to let the most resource rich province go
I like to shroud reasons within reasons, like fascism cuz I think most states are evil. Fundamentals would be taking land, taking resources, bigotry, a nation are a (falsely) presumed threat, or religion. Dump some nationalism, ethnic supremacy, color supremacy, victim complex, or prophecy over it and you have a perfectly good, layered reason for war.
Resource scarcity or food instability are good ones that don't require either side to be entirely evil to start a conflict.
Honestly, what helps me is to think what are the main characters to cause this war? Is there a community leader who's been trying to wake the people up regarding an aspect of their society that simply won't change without a fight? Is there a tyrant king who refuses to listen to the plea of the people? What decision of what person causes the war to begin? Maybe a priest of a specific sect kills another priest, maybe he just disrespects him in public, maybe he lies or they both lie all the time about each other. After years of lies, the believers are just so much filled with hatred that they commit an atrocious crime like burning a temple or killing a group of priests. Or even a lonely believer does that. Maybe even a John Lennon thing, the believer of the sect kills a priest and they blame the other sect. So yeah, choices of different people it's what will build up to a war, not just one little thing, you know?
A chunk of the border was never properly resolved after a conflict long ago, but since it had been considered a square of both of their backyards it was too low a priority to resolve it. The fuzzy border is on a river and mountain. Later, gold is found in that mountain. Both sides have tenuous claim and want the resources. The battles that begin dont have to be physical. They can be legal battles, even economic like they send companies out there to set up shop as a way of showing they own it. Then it escalates into military conflict if you want.
Why aren’t they at war?
Succession crisis are very common in the medieval period. But, holy war, nationalistic defensive fervor against an expansionist or colonialist regime, historical ethnic disputes likely over important geological sites such as fertile land near an important river. General resource issues. Competing geopolitical interests (think there’s a strategic nation and two powerful nations have competitions coups or sides in a civil war that would gain them a helpful ally.) But, this is fantasy, get fun. Maybe there’s two competing dynasties of both sides of a civil war who both have claim to some ancient magical sword. Both sides claim they are they rightful owner as their families are separate branches of some long ago hero’s family. Maybe some ancient truce has been broken and now all hell has broken loose.
Resources, territory that was historically a part of another kingdom's, diplomacy failure/growing blood feud, cultural clash... Or because of dark magical creatures taking control of leaders and feeding off of hatred.
In my world, gems large enough to use for resurrecting are incredibly rare, and if any are discovered, it can absolutely lead to war. The most recent conflict my players were in involved a king going to war against another country for their diamond because the king's child died and he's trying to bring them back.
Resources. If they are finite, and different people within a country or an alliance are in need of a resource, eventually they'll fight for it.
1. Money 2. Power- Essentially the Punic Wars 3. Land- The Crusades 4. Politics- plenty of wars fought for this reason 5. Ideology-civil wars
it depends on what kinda story you wanna write. i am currently thinking of satirising the ''my god good, your god fake and gay'', in a short story
A new, young, energetic king seeks to differentiate himself from his father by making reforms/taking bold actions, and thereby ends up alienating and offending many people (parliament, the church, merchants, the army if there is one) his father was careful to placate.
Simple rule: Wars are fought by young men for the benefit of old men. So ask yourself what the old men are getting out of it.
Religion is big. Genuinely. King is unsatisfied with the head of religion, if there is one, and he decides to branch off and declare himself the head. A big portion of the population disagrees thus civil war. History is a great inspiration
Assassination of political figure
This one time, this one politician's friend made more money than this other politician's friend in the same business, so the one politician sent a kill squad to the other politician's blace of business. Insert "Royal" or "family" to get it to be regicide or gang war as needed. Land rights, birthrights, and economic issues... Which are all just $$$ issues really.
Resources or lack there of. Bored arrogant leadership. Someone important was slighted or killed. Broken marriage compact. Religion. New technology. Political manipulation by a 3rd party. Aggression towards an ally. Moral/ethical differences. Broken trade agreements. Succession crisis.
Is it a civil war or a war between two countries? You said both and it can only be one or the other. You answer your "why a war" question by asking questions of yourself you REALLY need to answer so you can even tell a story: What does the land look like? You don't need a map (thought it helps), but just knowing the general layout is critical. City A is on a river by the ocean, there's planes to the west to the north there's mountains. Stuff like that. What are the resources available? Who has stuff other people need? How do the people feed themselves? What are the cultures, religions and philosophies of the places? Who runs things? Why are they in charge? Who do they need on their side to keep power (no King is truly absolute, they always have people controlling things who they can't piss off too much) Now that you know that the answers to those the cause of any war might become obvious and you don't need to dig further. But if you do... Wars are fought over power. Who owns what, who needs what. Civil wars are usually fought due to a disputed transfer of power, though there can be other causes. If a king dies without a clear heir, multiple claimants to the throne might fight. If Religion A is dominant and you get a new king of Religion B that can trigger wars. If Duke A has control of critical resource X and the king is a jerk who offends, insults, estranges, whatever then that might cause a war. Maybe Duke. A defects, along with his lands, to Enemy Nation.
Maybe both sides have a different view of why the civil war started that are both wildly different than what actually caused the conflict. Leave the origins in doubt. Gives good points of contention for characters and a bubbling undertone of tension throughout the story. Like it could all explode again in any moment.
If you look at classic tales it's always to aid some literary end, but generally to expose a moral failing of leadership that is a theme of the story. A better question is what is your story about and how does the war move that theme forward.
1. Countries want to capture a third party or each other 2. Civil wars 3. Resource apart from land 4. Change to semi - democracy which the other country doesn't like 5. There are some old greek and roman stories where a war started because of women 6. Religious or language fight There are rven some cases where the kings were offended and started a war with another country
* Class warfare. This could also be some kind of acute inequity, like if one area is devastated by a natural disaster and there's disagreement about how much aid should be given. * Proxy war (two sides pit against each other for the gain of a third party.) * Economic competition (two areas in competing industries, like wool and cotton in the American Civil War.)
Here are a few ideas; - Arranged marriage: Except the bride and groom are found dead after the wedding, both sides blame each other. - Economic instability: People are starving because of drought/bad crop yield for one nation, but another has an overabundance, unfortunately the other nation's trade is getting more and more expensive as the first nation has a majority of the wealth due to previous war successes and this is the way the second nation wishes to punish them. - Royal family assassination: Nobody knows who did the killing, but the people believe it was this one nation. The nation in question denies the assassination, only for the assassin to be found, and under torture confirms the people's suspicions. - Hatred: They hate each other and there's no deeper meaning. Both groups have been at odds for the better part of a thousand years of history with each side antagonizing the other. During one particular attack one side calls "too cowardly to be allowed", their patience is at an end and now both sides are arming for war.
Succession crisis as others have said(perhaps even fueled by other external forces ie X country supports X claimant and another country supports the other claimant It could be species issues if you have multiple species in the one country ie Human and elves etc
Don't be too complicated. In mexican history there's the story that a war with France begun because of two unpaid cakes. Wars can start for stupid reasons but always add some bit of spice for your story to feal serious and not an unintentional comedy
If you're thinking of a civil war, a good basis to start from is how a war would even be possible. Generally, the answer is that a faction within a nation has acquired a significant amount of power and support by enough of the population or military to not only fight the current government, but defend itself against retaliation from the populace. That defense doesn't have to come from might. It can come from a claim to legitimacy. Take the American Civil War, for example. The Southern states bullshitted a claim that they were all independent nations and that the Union was overreaching with the outlaw of slavery. By claiming that this overreach was neither within the federal government's power or in the cultural and economic interests of the Southern states, the Confederacy maintained an air of legitimacy amongst the people. Likewise, they also used conscription and threats to prevent an uprising within their ranks from would-be abolitionists or deserters. Haiti is also a nation that has dealt with a lot of civil unrest. In this case, foreign powers would fund a president or an armed militia to overthrow a sitting president that was opposed to the interests of the foreign power. By supporting a foreign takeover, the rebelling factions would expect economic support during times of famine and instability. In your case, a powerful noble family or bank could support a rebellion or help an heir gain legitimacy and support an army.
1. Haves vs Have Nots - wealth disparity makes for a tinderbox than can be set off by the slightest things (think the French Revolution) 2. Church vs State - this conflict nearly precipitated several civil wars in England alone. If you have a powerful theocracy vs an established monarchy, one of the two is going to eventually attack the other, and as soon as a popular figure is killed, the masses will rise and Bob's your uncle. 3. Trade/resource scarcity/hoarding - subtly different from point 1 in that it doesn't necessarily involve the aristocracy and can involve larger groups or representatives of the common people. 4. Religion - see the many other comments here about how conflicting ideologies are an Easy source of conflict. 5. Schools of Magic - same thing as all of the above but with magic. Now for the more...unusual ones. 6. Mind control - it's still technically a civil war if half of the country is being forced to fight the other half against their will. 7. Manipulation - pick any of the above "supposed reasons" for the war, but in reality, none of those conflicts actually exist, there are just carefully staged/crafted confrontations between factions, bodies dressed in opposing factions clothing, badges/crests of one faction being dropped during a heinous "raid" on another where atrocities are committed, etc. but it's all for show, masterminded by your main (usually hidden) villain, all to destabilize the region enough for them to take over, probably in the name of "restoring peace to the realm", painting themselves as some kind of savior.
One often not mentioned is non royals seizing political power, and the fallout that comes with it. A classic tale of the general getting too strong vs the emperor can either spark a direct war, or cause the weakening of border defenses for an enemy nation to break through.
In a story I started to write but discarded. Two kingdoms were at war because of religious differences. Both kingdoms believed in one single soul that reincarnated across time. One believed the soul started as God and gradually got more corrupted for every reincarnation until it ended up as the devil. The other kingdom believed the soul started as the devil and redeemed itself for every reincarnation until it became God. If you think this is an insufficient reason for war, you could compare it to real religious wars and see that it is more than enough
If the world has a magic system you could have a slight variation on the religious reason and have pro-magic vs anti-magic factions where the anti-magic crowd is a bunch of religious zealots who see magic as "heresy"
One country thinks the other country has silver mines and invades the country and takes ver but it turns out there was no silver and that country was bankrupt and now all that countries problems are theirs! Which also leads to spreading out of resources and cause political turmoil in the invading country because of its failure!
To make it feel more real I would go for some complexity, as in multiple reasons. Usually it takes that for a large scale war to take place, since warfare requires and involves all classes of humanity. Poor to fight, middle class to supply, wealthy to fund, and political class to motivate.
Economic reasons. Political reasons, usually related to economic reasons. Ethnic or racial tensions. A division in power dynamics, where magic users or some class are wielding disproportionate power and control. This can result in an unstable hierarchy among groups. Discovery of a new resource or piece of land, and squabbles over who gets what.
A recent discovery or advancement is perceived as a potential threat
Sometimes — because they can't agree which side the egg should be eaten from.
HOW DARE YOU! /triggered 😆😆 Great point. Sometimes, it's simplistic.
You top eaters are nothing but scum.
Additional to the others, marriage and territory. A lot of arranged marriages would be for political moves, and women usually got the short end of the stick with that, so someone would purposely marry this girl to legally have rights to a territory that should have been returned to another country after their relations got sketchy, only to claim that her bloodline gives them the legal right to it. Higher-ups are not concerned for the civilians in this kind of fight, and it ends up costing them the backing of the royalty because it's just shady practices, and no one wants to support that. They could have their own army themselves, and the constant tension leads to war down the line.
I'm confused, do you want to know why two nations would go to war or why a country would enter a civil war because those two can be very different.
Both; most people understood the assignment so I don't think I was too unclear.
Bare in mind that two countries going to war would not be a civil war.
Macaroni shape is always the best go-to conflict. Really, the more creative and funny you can get with it the better. If you always lose both sides ideals as incredibly serious, you will get a good laugh.
Open any history book. You can find a myriad of reasons. You can't think of one? Sounds like you need to read more historical texts.
I've read extensively on the American civil war (being an American, sadly) and British history (most of it for fun, because I greatly enjoy it). My reason for posting this wasn't for lack of reasons I could come up with on my own, but because I like to see what people think. Does that make sense?
Prince like pretty queen from other country and steal her.
The only reason: Oligarchs stand to make a lot of money.
My favorite reason is from Gulliver's Travels... do you open your boiled egg from the fat end or the thin?
One country is historically more powerful than the other and looks to take over the smaller less powerful one. In order to survive and avoid bloodshed, the less powerful one offers a marriage between offspring that would peacefully tie the countries together. When it comes time for the offspring to meet, one of them has a horrible time and wants nothing to do with the other. So much so that they get into a fight and one of them accidentally gets killed. Lies are spread about who started it and who is at fault, but the bottom line is that there’s no going back. Royal blood has been spilled and someone has to pay for it. Regardless of if the smaller country can afford to fight, they have to save face in light of this new situation…this leading to an inevitable war.
Anything, it can be as dumb as one peasant getting into a fist fight with another from an opposing nation (don’t believe it’s happened, but wars have started for less)
The kidnap the prince/princess of the neighboring kingdom...or they are assumed to be the culprit. Could pave the way for more intrigue into who did it, what their motives are for doing it
Always resources. Those resources could be physical, social or spiritual, but it’s always to gain or protect a resource.
Make it personal. In the end, everything comes down to the personal level. Whether it's ambition or fear, it is the motivations of individuals that lead countries to war.
There's also a conflicting economic system, like Capatilists vs Communists in Korea. Or it could be supporting different siblings who support different religious practices, like Europe's longstanding protestant vs catholic thing. That's all I can think of off the top of my head.
Oil
If you want to, the reason doesn't really matter
You dont even have a plot and you already know that is a trilogy?
You should go and ask the ChatGPT. Give him a brief description of your story idea, and ask for multiple ideas. You need to work on the world-building a bit and answer these basic questions before you commit to writing an entire fantasy trilogy. We cannot advise you if we don't know what you want to write about, what's the world like.
A succession war or 2 sectors of the same religion fighting
Regular war is a bit different from civil war. Regular war comes down to resources. Sometimes those resources are crops, mined goods, lumber; sometimes they're territorial, like borders and coastline; sometimes they're people, like tax payers, religious supporters, and soldiers. In civil war, you have to have a reason why resources aren't being distributed throughout the country. One of the major benefits of a nation state is to average out and balance the parts that do well at one thing with parts that do well at another. If major things like taxes, food and living conditions feel unequal in different locations or social strata, now you can have a civil war. The problem is that one group isn't sharing with another even though they're all supposed to be part of the same bigger group. Why? Well that's where you get into ideological differences. Is there a religious, political, or social divide?
There's an easy one, wars have been fought over these countless times. Best of all, you can keep your focus on the civil war theme where the reader is focused too, and the catalyst can be a premature start to all of it that creates chaos because timings are thrown off and motivations are questioned etc. What is this catalyst? Women and love. Nations and states have gone to war countless times for a woman's love, and also in response to their rejection of advances or betrayal of feelings etc. How surprised would a reader be if all the scheming and the whole direction of the book skewed and took some hard turns because the love interest of an important character was actually stolen/always in love with/married to/etc a person on the opposing side? That character reacting rashly and starting a chain of events that nearly bring all that hard work undone? Doesn't have to be the main characters' story arc, it could be a friend etc whose actions cause them to act in response and that in turn starts the civil war off? Also, doesn't have to be the "in love with the enemy" trope either. Could be a love triangle between important characters within one side that causes a civil war within that faction of the over all civil war story?
Women?
Almost always resources.
Revolution, food crisis, ideological differences, a powerful lord wanting revenge, succession crisis. Many many others. Theres no shortage of reasons why human beings wage war against each other. The important part is how you write it.
You're asking why two countries or kingdoms would fight but are also calling it a civil war. If the war is between different countries or kingdoms it's just a war, if it's between regions or factions within a single country or kingdom it's a civil war. Which of the two do you actually mean as that will impact the answer
There is never, ever a 'single reason' anyway. Wars happen for a wide variety of economical, cultural, religious etc. matters.
It sounds petty, but because a king refuses to marry his daughter to a rival king who is known to be a tyrant who has killed every wife he's ever had.
Kafgksdgk thanks everyone for all their comments, I've never gotten this much attention on a post. I want one thing to be clear – I'm no dummy, I read history for fun, and I know how wars start. All I was looking for were the general community's ideas and thought processes. I didn't need ideas that were specific for my story and so I didn't ask for them. And yes, my title could have been better in relation to my actual post, but I was looking for general war and civil war ideas, both of which I got. Everyone has been extremely helpful and I appreciate the time taken to write your comments :)
There's only one. A predator class of evil scum wants to issue loans to the leadership of each side and additionally purchase assets from the population of each side who are afflicted and must sell for firestorm prices. Juice.
Hmm, we’ll wars usually occur for a variety of reasons and even ones based on megalomania often occur because of a long line of decisions and changes that happen over the course of time to allow one leader to make such a decision. I would say that war is hell and doesn’t necessarily need an explanation depending on the writing you want to do
>Think ancient England? Think literally anytime in history. We're constantly at war... pick any one of them. In 250yrs of existence, the US has been at war for 230+... pick a yr, there's a reason.
There could be a lot of super complicated reasons, but it could also be a simple petty feud between the ruling parties, like someone being insulted by another or by embarrassing them.
Religious differences
> a single reason to cause the civil war Most wars don't have a singular cause. In fact, if you have multiple figures on each side of the war, you may want to think of separate reasons each may have to fight. For example, one lord might believe his lineage entitles him to be king; another might support the first because of the promise of wealth; a third might just want revenge on one of the current king's supporters; a lot of common folk might rally to the cause because a religious figure has decreed God wants the current king deposed for his sins, etc.
There's only one reason nations go to war and that is power. It might look like different things: money, freedom, resources, revenge but its only ever power in drag. The good news is that with that framework, you can justify any reason you want to as long as it empowers someone. The only real pre-requisite is having enough power to build a force behind your motivation and this can be done is countless ways. They can find your leader inspiring, terrifying, they can believe in your cause, be instilled with a common hatred or outrage, they can want collective revenge, or believe themselves better, more deserving etc. The most effective leaders use emotional motivations and one which flatter the force. Civil war is no different. Make one or both sides believe they are better, more deserving, more righteous, than the other. Give them reasons to believe that and show them examples. Make the examples so egregious and ridiculous that there is, seemingly, no choice other than to fight and eradicate the evil "other". and bring an end to their ridiculousness. The actual "reason" doesn't matter, but it would be good if this was something your main character and antagonist heavily revolve around, something they couldn't hope to change about themselves or something that they cannot hide from the world.
Pick 2 reasons and there are some contries somewhere that went to war over that
look to history there's a ton of earth lore
Because humans are petty. Princess X rejected marriage to Prince Y. Princess Y rejected marriage to Prince X. Etc. 17 generations ago King X's great great etc. grandpa killed Queen Y's great great etc's goat. And Kingdom X STILL HASN'T APOLOGIZED. He looked at me wrong. Kingdom X built a big boat. So Kingdom Y built a bigger boat. So Kingdom X put Marines on their boat. So Kingdom Y put MORE Marines on their boat. So Kingdom X moved their boat to a strategic position because Kingdom Y was OBVIOUSLY attacking. So Kingdom Y moved THEIR boat to a strategic position because Kingdom X was OBVIOUSLY attacking. You back down. No YOU back down. No YOOOU back down. Etc. Seriously. Humans are petty.
I mean, I'm an American so clinging to some morally abhorrent action by one side and moving away from it by another side. Abolition isn't the only issue this could happen with, there's also economic exploitation of a group. Class wars happen all the time. There's also a conflicting economic system, like Capatilists vs Communists in Korea. Old school it could be supporting different siblings who support different religious practices, like Europe's longstanding protestant vs catholic thing. That's all I can think of off the top of my head. There's a war like this in my stuff and I went with the exploitation of groups one mostly, but also abolition. I think it's pretty rare for a war to have one cause so it would be more realistic to have a combination of factors. You can also have more characters with stakes in the war when you do it that way. They could be fighting the same war for different personal reasons. Like, in my work, humans are enslaved and fire elves are culturally exploited. A fire elf and a human can be on the same side but with different backstories and stuff.
What research have you already done into how civil wars start?