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Crusader Kings 3: How To Declare War (Things You Should Know)

Know how to declare war in Crusader Kings 3. Learn about Casus Belli and how to attack territories in CK3 easily.

If you want to expand and grow your territory, war is inevitable, especially in CK3. There are many things you need to know before you declare war in Crusader Kings 3 and that’s what we will share with you in this guide. You might need war to get more resources so, here’s how to declare it in the game.

How to Declare War in Crusader Kings 3 (CK3)


The very first thing you should know is Casus Belli. What’s Casus Belli, you ask? Well, by definition it is an act that either provokes or justifies a war. To put it simply, it is a reason for going to war. The game will tell you if you have any disputes or conflicts with another territory and you can choose from the options shown. Each of them will have some requirements. You can declare war without a Casus Belli, but it can have a bad impact.

Do note that you have to look at the difference between yourself and your potential enemy in terms of army, allies etc. before declaring war. If you have a strong army with enough soldiers, you have a better chance of winning the war. You can choose to hire mercenaries for this purpose too.

Once you are ready, here’s how to go about it. Click on the region you want to capture and then see who is currently holding the title there (the Ruler). When you right click on their photo, you will see the Declare War button.


Also Read: How to Fix Crusader Kings 3 Crash on Startup Issue

Next, choose the Conquest type as well as the Casus Belli. The final step is to click the Declare War button and then a war will be declared, signified by the change in background music.

An important thing to ensure is that you should have all the concepts clear by playing the tutorial. That’s because you don’t want to be caught up in a war without knowing what exactly you should do at that point. So, complete the tutorial to get a good grip on how the game functions.


When you do everything right, you will see that you have succeeded in winning the war. If you are on the path of losing, you can surrender or declare White Peace.

That’s all the basics of how to declare war in Crusader Kings 3. Don’t miss our other articles on CK3 Console Commands, how to fabricate claim, how to raid and know if there’s a multiplayer option in the game.