Vietnam War by alex.aleksandrovski Posted on September 5, 2010 The United States entered the war to stop the spread of Communism in Southeast Asia. It lasted more than 15 years, from 1959 to 1975 and was the longest and the only war that the United States lost. About alex.aleksandrovski 5081190214592784 View all posts by alex.aleksandrovski → This entry was posted in September 7 Assignment, TV24. Bookmark the permalink.