The event that marked the beginning of the Russian Revolution was the February Revolution of 1917. Triggered by widespread discontent over food shortages, military failures, and autocratic rule under Tsar Nicholas II, the revolution resulted in his abdication. This uprising led to the establishment of a provisional government but ultimately set the stage for the more radical October Revolution, where the Bolsheviks, led by Vladimir Lenin, would seize power. The revolution initiated profound political and social changes, ultimately resulting in the formation of the Soviet Union.