text: A peace demonstrator taunts military police during a confrontation in front of the Pentagon October 21, 1967 during a large anti-Vietnam War protest in Washington, D.C..The Vietnam war, which cost thousands of lives and divided American opinion, was the most unpopular in U.S. history. April 1995 marks the 20th anniversary of the fall of Saigon to the communists and the end of the war. cm/FLS REUTER/BETTMANN