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. He accepted the right of the anti-war movement in the U.S. to have exercised their freedom to protest, and he adopted a live-and-let-live attitude towards those who had evaded the draft. Nor did the vast changes in American social mores that had taken place during his absence bother him, as it did many other former POWs. McCain returned to Saigon in November 1974; he and a couple of other former POWs received the National Order of Vietnam, that country's highest honor. He also spoke at the South Vietnamese war college, five months before Saigon fell. McCain resolved not to become a "professional POW" but to move forward and rebuild his life. Few thought McCain could fly again, but he was determined to try, and during this time he engaged in nine months of grueling, painful physical therapy, especially to get his knees to bend again.