Russian Civil War
The Russian Civil War was fought between the Bolshevik lead Red Army and the White Army, which had many factions. As both sides committed gross atrocities, the White Army had only a small one wanted to restore the monarchy.
Several other nations intervened in the war on the side of the Whites, including France, the United Kingdom, the United States and Poland. Despite this assistance, and partly due to internal disunity, the Whites lost the War to the Red Army.