Russian Revolution:

The Russian Revolution, from 1868-1918, was when the Russian people were sick of the Tsar, the person with all the power, and their lifestyle. They killed the entire "royal family", and Russia became communist and entered the Soviet Union.

World War 2

Russia was an ally in World War 2. They originally had been friends with Germany/Hitler, until during their 10 year non-aggression pact (which basically was them prepping their armies for each other) Hitler broke the pact and sulfide attacked Hitler. Russia became a major part if the Allies, and Joseph Stalin was one of the leaders of the Allied Powers. This war lasted from 1939-1945, but TECHNICALLY is still not over.

Russia's Wars

The Cold War

Even though the Soviet Union was on the Allied side, all of the other Allies didn't trust Joseph Stalin, and didn't want communism spreading. Although these two "superpowers" didn't directly initiate war, they both had a race to make the most nuclear weapons and who could reach the moon, and further, first. It's lasted from 1945 to 1985, though it's hard to tell because it wasn't an "official" war.