How to Get Casus Bellis in EU5: Completing and Solving Strategies

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In Europa Universalis 5, expanding aggressively is based on the idea of legitimacy—you can’t just take land without a good reason. This makes the Claims mechanic very important. Unlike earlier versions, EU5 makes gaining valid Casus Bellis (CBs) more strategic and tougher, discouraging reckless expansion.

A valid Claim is essential for a targeted, effective conquest. It helps you reduce the cost and time needed to add new territories to your empire. This guide will explain the ways to secure these territorial claims so your expansion stays quick and legitimate in the eyes of others.

How to Get Claims

While there are other types of Casus Bellis, like those from rivalries, trade disputes, or random events, land Claims are among the most powerful because they lower the war costs when attacking for land.

There are two main methods to get a Claim:

Through Parliament – You can persuade your Parliament to grant you a Claim by going through a voting process. Success depends on chance, influenced by events and how well you please the Estates involved.
Using a Spy Network – You can build a Spy Network in the target nation and then use it to create a Casus Bellis through the “Create Casus Belli Hostile Action” option.

Note: The Spy Network method is only available if the target nation owns land that was once yours.

Getting a Claim isn’t the only way to expand your territory. You can declare war without a Casus Bellis, but this will come with bigger disadvantages, especially since the land will cost more in terms of warscore.