The Bolshevik Revolution and the Birth of the USSR

In late 1917, the Bosheviks, led by Vladimir Lenin lauced a nearly bloodless coup against the provisional government that was set up after the abolition of the Russian monarchy. After successfully seizing power, the Bolsheiks along with Lenin set up the world's first communist state in Russia.
A civil war followed which saw a victory for the Red Army and on 30 December 1922, the Soviet Union was established.
Oddly enough, Karl Marx (the father of communism who died 34 years before the Russian Revolution) didn't quite see a communist state that well in Russia but Lenin proved him wrong.