The leader during the Russian Revolution of 1917 was Vladimir Lenin, the head of the Bolshevik Party. Lenin's return to Russia in April 1917, following the abdication of Tsar Nicholas II, marked a pivotal moment during the turmoil of World War I. His leadership and ideology, largely captured in his April Theses, called for "peace, land, and bread." The Bolshevik seizure of power in October 1917, known as the October Revolution, ultimately led to the establishment of a communist government and the Russian Civil War, significantly altering the course of Russian history and paving the way for the formation of the Soviet Union.