The Four Years War was a conflict that took place between the United Federation of Planets and the Klingon Empire in the mid-23rd century. (FASA RPG: The Four Years War) After the war ended, the political movement Quattuor Anni (Latin for "Four Years") arose. Among its numbers were Starfleet veterans and families of casualties of the Four Years War. (More Missions, More Myths 18: "Fatal Vision")