What key event marked the abdication of Tsar Nicholas II?

The abdication of Tsar Nicholas II was a significant moment in Russian history, marking the end of more than three centuries of Romanov rule. This event occurred during the February Revolution, which unfolded in 1917 amid widespread unrest due to food shortages, military defeats in World War I, and growing discontent with the autocratic rule of the Tsar.

During the February Revolution, mass protests erupted in Petrograd (now St. Petersburg), with workers and soldiers demanding an end to the Tsarist regime. The situation escalated as protests intensified, leading to a loss of support for Nicholas II from key military factions, as well as his own advisors. The pressure mounted, culminating in Nicholas II's decision to abdicate on March 2, 1917. His abdication led to the establishment of a provisional government, initiating a period of political upheaval and ultimately paving the way for the Bolshevik Revolution later that year.

This context highlights why the February Revolution is the key event that marked the abdication of Tsar Nicholas II, as it was the revolutionary movement that directly led to the end of his rule. The other events listed, such as the Bolshevik Revolution and the Kornilov Affair, occurred later and were significant