Answer:
The Russian Revolution was actually three revolutions. The first was in 1905, but it did not accomplish much aside from the creation of the weak Russian Parliament called the Duva. The Czarist regime maintained real power.
The second was the February Revolution of 1917. This resulted in the abdication of Czar Nicholas II and the overthrow of the Czarist government. The revolutionaries could not agree on how the new country would be governed and they split into factions. Two factions were the Mensheviks and the Bolsheviks, which led to the third revolution.
The third revolutions was the October Revolution of 1917, which was more like a civil war than a revolution. The Bolsheviks under Lenin succeeded in wresting full power over the new government, which became the USSR.
Yes, so called "The Great October Revolution" happened in 1917. But the 1st (unsuccessful) revolution was in 1905 and Tsar Nikolas had been dethroned in February.
