The event that led to the establishment of the first Russian Republic was the Russian Revolution of 1917. This monumental event unfolded in two major phases: the February Revolution, which led to the abdication of Tsar Nicholas II and the end of the Romanov dynasty, and the October Revolution, which resulted in the rise of the Bolsheviks under Vladimir Lenin. The revolution marked a drastic shift from imperial rule to a republican form of governance, laying the groundwork for the Soviet state. This moment was pivotal in shaping the political landscape of Russia and the world.