During the war, over 16 million Americans served in the United States Armed Forces, with 405,399 killed in action and 671,278 wounded.[3] There were also 130,201 American prisoners of war, of whom 116,129 returned home after the war.[4] Key civilian advisors to President Roosevelt included Secretary of War Henry L. Stimson, who mobilized the nation's industries and induction centers to supply the Army, commanded by General George Marshall and the Army Air Forces under General Hap Arnold. The Navy, led by Secretary of the Navy Frank Knox and Admiral Ernest King, proved more autonomous. Overall priorities were set by Roosevelt and the Joint Chiefs of Staff, chaired by William Leahy.