The fate of the German Revolution and the Communist International (Comintern) were closely intertwined. Mass protests and strikes brought down the Kaiser in November 1918, leading to a tumultuous period of revolution and counterrevolution, culminating in the missed opportunity of 1923, when it appeared to many that a socialist revolution was on the agenda. Throughout this period, the German left went through a series of splits and regroupments in an effort to build a communist party independent of the moderate German Social Democratic Party (SPD), which had backed the war in 1914 and had worked to contain the revolutionary potential of German workers. The Comintern learned from the tactical and strategic debates on Germany. It also exerted influenced on the German revolutionaries, in both positive and negative ways. This talk will examine how the failure of the German Revolution sealed the fate of the Comintern and the Russian Revolution.