Not really the whole involvement with Vietnam was due to French. The thing is France returned to Vietnam after 45' when Japan surendered to Allies.
See it all started in 1945, Japan ousted the Vichy French and assumed direct rule over Vietnam; the Viet Minh stepped up their anti-Japanese activities. By the time Japan surrendered to the United States, in August 1945, it represented the strongest political force in Vietnam. On September 2, 1945, using the words of the American Declaration of Independence, Ho Chi Minh proclaimed Vietnam a free and independent country. His hope was that his wartime allies would restrain the French from attempting to dominate Vietnam ever again. Instead, the British, in the south, and the Nationalist Chinese, in the north, enabled the French to return. Within a year, the Viet Minh was once more fighting for the independence of Vietnam against the French.
Although the United States disapproved of French tactics, the desire to support its European ally, combined with a growing concern over Communist power in Asia, led first President Truman and then President Eisenhower into close cooperation with the French war effort. By 1954, when the Geneva Conference brought a temporary end to fighting in Vietnam, the United States was paying over 75 percent of the French war costs.
Despite the Viet Minh's massive victory over the French at Dien Bien Phu, the United States tried to persuade the French to keep fighting. The Eisenhower administration even considered the direct use of U.S. military force, including combat troops and nuclear weapons. Neither the British nor the U.S. Congress was enthusiastic, however. Eisenhower and Secretary of State Dulles ultimately acknowledged the Geneva Agreements, which divided Vietnam at the 17th parallel, a temporary demarcation line meant to separate French and Viet Minh forces until elections scheduled for 1956. Ho Chi Minh firmly controlled the area north of the line, while the area south of the 17th parallel was put in the hands of the conservative nationalist Ngo Dinh Diem. It was hoped that the nationwide elections scheduled for 1956 would lead to national reunification.
We never saw the reunification...
