Vietnam was of course originally colonised by the French last century, and there followed a long resistance by the Vietnamese people against the French colonial regime. The French were of course defeated by the Japanese during World War Two.
However, at War’s end, when the Vietnamese nationalist leader Ho Chi Minh expected to take control over a free Vietnam, the French with British help returned and reestablished their exploitative colonial rule. As a result there then followed a long conflict between Ho Chi Minh’s Viet Minh against the French. The French were finally defeated and withdrew in 1954.
However, this was not the end of the struggle for freedom for the Vietnamese People.
Remember, this was a time at the height of the Cold War and the Korean conflict. As such, the US had this narrow minded containment policy. It perceived communism was expanding everywhere and everywhere directed by the Soviet Union and the Red Chinese.
As such the United States believed that Ho and the Vietnamese people’s struggle was nothing less than communist expansionism directed by the Soviet Union, and therefore had to be military contained. Nothing could be more further from the truth.
As such, the US had supported the French, and when the French were thrown out, then they began to support their own puppet dictator Diem. The Viet Minh of course picked their guns up and began to fight Diem and his forces and then the Americans who increasingly intervened.
What developed was a conflict ostensibly between North and South Vietnam, two artificial creations put in place in 1954, as a temporary solution to the conflict.
Elections were to be held two years later, but Diem of course refused and the conflict was on again - with the Vietnamese people fighting for reunification and sovereignty, and the Americans and their Vietnamese proxies fighting to prop up the regime and defend US economic and geo-strategic interests in the name of containing communism.
The US of course came up against People’s War for the first time in Vietnam, and the conflict was largely lost by 1963 - though it ultimately dragged on to 1975 with devastating losses to both sides.
The United States was of course forced to rethink the whole way it saw itself and the world, and to redefine itself accordingly. This was done temporarily under President Carter. But it was largely turned around again by Reagan and the militarists that supported him.