The Russian Civil War was a civil war fought from November 1917 until October 1922 between several groups in Russia. The main fighting was between the Red Army and the White Army. The Red Army was an army of communists. The White Army opposed the communists. Other forces fought against both these groups or sometimes helped one against the other. Foreign countries such as Japan, Britain, France and the United States sent troops to help the divided white army. The Red Army won this war because their army was better-organized and they held the best territory. After this war, the communists established the Soviet Union in 1922.