Military leadership in the American Civil War was vested in both the political and the military structures of the belligerent powers. The overall military leadership of the United States during the Civil War was ultimately vested in the President of the United States as constitutional commander-in-chief, and in the political heads of the military departments he appointed. Most of the major Union wartime commanders had, however, previous regular army experience. A smaller number of military leaders originated from the United States Volunteers. Some of them derived from nations other than the United States.