This was known as the Anti-French war in Vietnam as it was the Viet Minh fighting to push French forces out of the country when it spread to Combodia and Laos
China is now under Mao Zedong's Communist Government and her if offering power to another potential communist country in Asia.
The combination of the Viet Minh and WW2 allowed for the Viet Minh to push the last of the French out of Vietnam and it combined under the leadership of Ho Chi Minh and created a communist state.
The US, France, UK, Soviet Union, and China met in Geneva to end the fighting and came to the agreement, the Geneva Records, to split Vietnam in two with the Northern half ruled by the Viet Minh and the south ruled by the State of Vietnam and Emperor Bao Dai.
America became involved after the Gulf of Tonkin and continued to fight against the Northern Communism.
The US helps the south communist rebel group Viet Cong and throws South Vietnamese President Deim out of power.