Sometimes as you march through centuries of history trying to establish yourself as a thriving new country in Europa Universalis 5your neighbors don't really like to see you grow as a nation, and certain actions throughout history are sure to lead you into a grueling, expensive series of battles.
Going to war in the EU5 is no small feat. You have to consider the strength of your country vs. your opponents, all the possible allies on both sides could enter the fight, and the potential geopolitical outcome of being the aggressor. Keep an eye on your war results and strive for greatness through battle!
War overview
Get a Casus Belli to avoid belligerence
Before you can declare war on another EU5 country, you first need one Casus Belliwhich is yours the purpose of going to war with that country. During your campaigns, you will engage in various forms of diplomacy with other countries. This can include sending diplomats to the country, establishing spy networks and improving public opinion, but another thing these diplomats can do is to either find or manufacture a Casus Belli if there is a country you are trying to go to war with.
But sometimes the game will practically hand you your Casus Belli on a silver platter as relationships break down through geopolitical history. You will come across things like conflicting claims to thrones such as those which may arise from the personal unions created when heirs have claims to the lands of several countries, expansion into claimed territoriesand more.
Like I said, you Can declare war without a Casus Belli, but that carries the added penalty of increasing your opposition quite steeply, so either provoke the other country into giving you a reason for war, or have a spy invent a reason for you to prevent this.
Casus Belli has a lifespan of about four years during which you can press the question and act, and each will also have one unique war targets for each country given the circumstances that lead them into war. Countries involved must achieve their war objectives to be declared victorious in the battle, but completely taking over the territory of another country you are at war with is also a valid (if not much more complicated) way to win.
Build your military force and monitor your units
Before you will be taken seriously on the world stage when it comes to military power, you have to work for improve your armies and navies before war, of course, but especially during. You should make sure each unit has a general to lead them into battle, and the game lets you choose from a roster of capable candidates from across your country.
If you have units without a leader during battles, the game will warn you with a band warning in the top bar. Clicking it will open the information panel for the first device on the list, until you've fixed the issues with each device listed.
Automations are a great way to keep things moving, but there are a number of ways you can work to preserve and acquire your military force through reforms, advancements, and more. These methods of improving your armies include:
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Diversify your warfare tactics by researching militaristic advances in each age throughout the game, to ensure you always enter the fray with the latest gear and unit types.
- Appointing strong leaders for each unit involved in combat, as your men will line up most effectively behind a leader who is willing to fight with them.
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Make sure you are use the correct formations for any given battle, change the placement of your units as needed in the military panel as needed between major battles.
- Use your geography to your advantageby building strong navies like a coastal or island nation and focusing on land units like landlocked states.
Along the way, though, you need to make sure you are keep an eye on morale and exhaustion in your troops, as the fighting will really start to take it out of them before too long. War exhaustion affects the country at largewith increased exhaustion leading to reduced trade, production and pop growth.
Wars end through victories or treaties
As mentioned above, countries will go to war with clear war goals for their country which must be achieved in order to be declared victorious in a war. But if you're tired of fighting—if morale is low, money's running out, and the war has just gone on too long—you can also choose to end war by treaty also.
Treaties have different terms, depending on the type you want to sign with the other country and its allies. Whoever proposes a treaty sets the conditions in said treaty, which will include things like:
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Transfer of power in held territories, which is a great way to expand your empire if you want to grow.
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A list of demands for things like Goods or Pops, which will increase a country's opposition on the world stage.
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Humiliating element, which offers a Prestige bump to your country in the aftermath.
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Monetary reparations, either given to another country after war reparations or requested by another country if the fighting was on your home front.
The game will tell you right away if the other country is willing to accept your proposed treaties. Their likelihood to accept is determined by a list of factors, including things like their strength as a country compared to yours, the number of allies they have, the terms proposed in your treaty, the peace cost to each country if they were to accept the treaty, and more.
General Warfare Tips
War costs money, lives, morale and energy
There is a lot that should go into the decision to declare war on another country, then warfare is costly and exhausting for your countrymen and your treasury. You have to make sure that you don't just have built your armies and/or navies in a way that contributes to decisive victories, but as your country can afford to finance war efforts.
When pops filter into your units to fight, especially in the early days of the game, you'll often find that your Pops decrease as civilians go to war. People from other countries are less likely to migrate to your country if you are actively at war, so you need to make sure you are keep enough people at home to keep the cities running while the military fights the war.
You can also choose to engage in certain other types of warfare, such as hiring bands of mercenaries to fight on your side or seeking out all kinds of powerful political allies around the world to shore up your defenses. On the whole, though everyday life must happen in your cities during wartime as well, so make sure you don't focus too much time, energy, and ducats on the fight.
Monitor your war results
During the skirmishes that make up your wars, you'll find that each action leads to a change in your war score, a value that indicates how well your country is doing in the war. You'll discover a number of things that change your war outcome in EU5, including a boost from having built specific buildings in your nation's capital, having access to ports or trade routes to ensure an even supply of goods entering and leaving the country throughout the battle, the number and strength of forts in your cities, and more.
However, the most pressing way to change your war result is through win or lose battles along the road. You will engage in lots of skirmishes with the other country(s) involved in your war, potentially being able to call allied countries for help in combat (although they only accept if they are not in a war of their own at the time).
The higher your war score, the better you perform in the war overall. Keep an eye on your war score to know when the skirmish is finally coming to an end, and use it to influence your decisions on how to end the war.
Historical wars arise as situations
Depending on which country you have chosen to play as in your EU5 campaign, it is entirely possible that you will be forced to deal with a real historical situation during your rule. Do you know that your chosen country is going to war with another country in a certain year, or that there is a health scare shaking things up, or that suspected insurgencies are going to start happening in your locations?
Keep an eye out for pop-ups for events and situations throughout your rule, as these are often triggers to lead your country into a specific historical war, such as the Hundred Years' War or the Crusade against Lithuania. The game will always show you an icon to denote the historical choice made by the country you're playing, and hovering over it will give you a preview of the outcome of your choice.
You can choose to fight these historic wars and make sure your country comes out on top, change the course of history and lead the war to an alternate victory for another country, or even try to change early game decisions to try to prevent war from ever breaking out at all. The choice is really yours, but they will be made on these pop-up cards, so pay attention when they occur!
