In Europa Universalis II, a vassal is a country which has assumed a subordinate relationship to a dominant country, called the "suzerain". Historically, being a vassal almost always implied providing military assistance to the suzerain when called, and sometimes the payment of tribute. In EU2, vassalization is a kind of diplomatic agreement in which the obligations of military assistance and tribute are reversed from history. A vassal always pays tribute from its province taxes, but is not necessarily a part of the suzerain's alliance.