Russia, as the Soviet Union, did not leave World War II; rather, it was one of the main Allied powers that fought until the war's conclusion in 1945. The Soviet Union played a crucial role in defeating Nazi Germany, particularly noted for its significant contributions on the Eastern Front. The war in Europe officially ended on May 8, 1945, with the unconditional surrender of Germany.
1918
World War 1 and World War 2 And we cannot leave out the Cold War
Russia :)
Russia as they were dealing with the Bolshevik Revolution
in 1917 russia withdrew from the war specifically December 1917
1917.
Russia last full year of World War I
Russia
22 Jun 1941 when Germany invaded Russia
The Revolution in Russia ended Russia's involvement
Britain left World War I in 1918 when the war ended.
Russia joined world war 1 in 1914