The Russian Revolution was a revolution provoked by Bolshevik (communist) followers against the Russian monarchy regime which took place in 1917. However, the revolution was crushed by Tsarist forces led by Tsar Mikhail, who is presumably Nicolas II's brother and took over Russia after his abdication. The leaders of the failed revolution, including Vladimir Lenin, were sent to labor camps in Siberia.
The failure of the revolution meant that there was no Russian civil war and Communism never took hold. But also allowing Russia to continue participating in the Great War. It is possible that after the failed revolution, the Tsar became increasingly paranoid, which eventually led to Russia's isolationism and the construction of the Red Curtain in 1921.