Call to Arms

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This article is accurate for the latest versions of EU3, Napoleon’s Ambition, In Nomine, Heir to the Throne and Divine Wind.

A Call to Arms is a diplomatic option that summons one nation to the assistance of another. A nation can receive a Call to Arms if one of the following is true:

  • If a nation declares war on another, the allies of both aggressor and defender will receive a Call to Arms;
    • Nations can also be called in mid-war by their allies on either side. This can result in cascading wars in which huge webs of alliances come into play. (DW.png)
  • If the Attacker has been Warned, the Warner will receive a Call to Arms;
  • If the Defender has been Guaranteed, the Guarantor will receive a Call to Arms;
  • If the Defender is a member of the Holy Roman Empire, the Holy Roman Emperor will receive a Call to Arms;
  • If a nation of one Religion declares war on another, the Defender of the Faith will receive a Call to Arms to assist the Defender, if they share the same religion.


If the nation receiving a Call to Arms does not answer, or declines to assist, they will automatically have any Military Alliance with the ally at war broken.

Situations can arise where a nation is allied to both Aggressor and Defender; in this case, he may only choose one to answer and will go to war with the other. In this case only the Alliance with the nation answered is kept. If he selects neither he will lose both alliances, but not go to war with either state.

For AI nations, the greatest determinant of how to reply to a Call to Arms is trust. The higher the level of trust, the more likely the AI is to answer favourably. For the player, answering Calls to Arms, the levels of trust and of relations will increase positively with the nation Calling. Similarly, if Calls are repeatedly ignored relations will visibly drop, as will trust.


If a country calls you to arms, and you save and then resign, you will not be obliged to accept/deny the call to arms, and the notification in the bottom-left corner will disappear. You will continue to be an ally of that country, and no negative effects will follow. You also keep the alliance CB. This exploit can be very useful if one were to save, look at the country where the call to arms came from, see who it's at war with, determine whether he/she wants to accept it, and then accept it if he/she wants to, or resign and re-load the save file. This is particularly useful when your ally decides to declare war on a country with no CB, this way you can keep the alliance without having to suffer the same -2 stability hit.