The pivotal event that marked the beginning of the Russian Revolution in 1917 was the February Revolution. This uprising led to the abdication of Tsar Nicholas II and the end of centuries of Romanov rule. Economic hardship, military failures in World War I, and rising discontent among the populace due to food shortages and political repression fueled the revolution. The February Revolution resulted in the establishment of a provisional government, which was later challenged by the Bolsheviks in the October Revolution, leading to significant political, social, and economic changes in Russia.