In World War 2 Vietnam was taken over by Japan. But after WWII Japan left Vietnam and the French took control and gave power to Emperor Bao Dai. However France took back power. But the Chinese and Soviet Union helped north take control of part of the country. But both sides wanted to unify Vietnam. However, unlike the north south Vietnam wanted to be under democracy but the north wanted to be under communist control.
The US started to get involved in 1954. Soon after the north was taken by the communist government. Vietnamwas soon divided in the middle along the 17th parallel. and one year later the war stared.