 McCain was promoted to commander effective July 1973 and attended the National War College in Fort McNair in Washington, D.C. during the 1973–1974 academic year.There he intensively studied the history of Vietnam and the French and American wars there, and wrote "The Code of Conduct and the Vietnam Prisoners of War", a long paper on the Vietnam POW experience as a test of the U.S. Code of Conduct.By the time he graduated, he concluded that mistakes by American political and military leaders had doomed the war effort.