The War in Vietnam

Historians often refer to the Vietnam War as America's longest war because it can be dated from President Harry Truman's commitment of $15 million to aid the French forces in Indochina in 1950 to the fall of Saigon in 1975. The reasons the U.S. became involved in Vietnam are complex. Briefly, American policy makers beginning with the Truman administration believed that the spread of Chinese Communism in Southeast Asia threatened the world balance of power as construed by the cold war. The so-called "domino theory" held that the entire region would "fall" to communism if the U.S. did not support South Vietnam against incursions from the north.

For several years the U.S. aided the south Vietnamese with technology, material, and military advisors. Intensive American involvement in Vietnam began in 1965 when President Lyndon Johnson sent U.S. Marines to defend Danang airfield. More than 15,000 American...