The United States Army Air Forces (USAAF) was the aviation component of the United States Army primarily during World War II. The title of Army Air Forces succeeded the prior name of Army Air Corps in June 1941 during preparation for expected combat in what came to be known as World War II. Although countries such as ally Great Britain had a separate Air Force, the Army Air Forces were part of the US Army and a direct precursor to the U.S. Air Force. The USAAF formally existed between 1941 and 1947 as an autonomous part of the U.S. Army, co-equal to the Army Ground Forces and Army Service Forces.