The Viet Nam War was similar to the Korean War in that the United States and the democratic powers of Europe wanted to contain communism. In addition, Dwight D. Eisenhower, the allied leader on D-Day and then president of the United States introduced the "Domino Theory". Eisenhower believed that if Vietnam fell to the communists the other southeast Asian countries would also fall; just like dominoes.
Vietnam was a French colony prior to World War II and the French had treated the Vietnamese people very brutally. The French worked the Vietnamese people to death harvesting the vast rubber trees that grew abundantly in Viet Nam.
Ho Chi Mihn led a gorilla rebellion against the French and went into the mountains when the Japanese occupied Viet Nam. When World War II ended the French returned and Ho Chi Mihn and his followers defeated the French at Dien Bien Phu. Thousands of Frenchmen lost their lives in the battle or in their march to captivity in North Viet Nam. The French pulled out of Viet Nam and the United States entered the conflict.
In 1955, The Republic of South Viet Nam was proclaimed and America began to increase its involvement in the conflict; in order to protect South Viet Nam from communism. Ho Chi Mien was unwilling to accept colonial rule of South Viet Nam, and therefore, sent his guerrilla forces into South Viet Nam by the way of the Ho Chi Mihn trail.
When President Kennedy was assassinated, Lyndon B. Johnson became president of the United States. In 1964 Johnson began intensive bombings of the Ho Chi Mihn trail; even in countries outside of Viet Nam. The bombings and battles became a daily site on American televisions and a tremendous protest movement ensued. At one point American student protesters were killed on an Ohio college campus.
After hundreds of thousands of deaths on both sides; America pulled all forces out of Viet Nam and Ho Chi Mihn united the country under communism.