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

A guarantee is a diplomatic option that promises the defense of one country by another, whether or not they are allied. In the event that the guaranteed nation is attacked, the guarantor receives a Call to Arms and then has the option of joining the war; if it is not answered, the guarantor will be penalised by 25% of his Prestige. Proclaiming a guarantee on someone raises relations by 10 points.