Trotsky is the most important theorist and practitioner of revolutionary insurrection in the socialist movement to date. As leader of the Petrograd Soviet and organiser of the Military Revolutionary Committee, he oversaw the first successful attempt to topple a capitalist government and put the working class in power. In a number of subsequent works, Trotsky laid out the political, social and military conditions which allowed the October Revolution to win. This talk will explore the lessons of the insurrection and the debates it sparked on the left.