During his convalescence, he read Marx and became a communist, mainly by the influence of the father of a nurse with whom he had developed a relationship. He spent the rest of the war studying economics at the universities of Berlin, Kiel and Hamburg. Sorge received his doctorate in political science (Dr. rer. pol.) from Hamburg in August 1919. He also joined the Communist Party of Germany. His political views, however, got him fired from both a teaching job and coal mining work. He emigrated to the Soviet Union, where he became a junior agent for the Comintern in Moscow.