Army - Vietnam Combat Veteran, 5th Military Police Company, 5th Infantry Division - MugUnited States military involvement in the Vietnam War officially began on August 5, 1964; however, the first U. S. casualty in Vietnam occurred on July 8, 1959. Approximately 2. 7 million American men and women served in Vietnam. During the war, over 58,000 U. S. military members lost their lives and 153,000 were wounded. There were 766 prisoners of war of which 114 died in captivity. The war was officially ended by Presidential Proclamation on May 7,