This thesis explores the relationship between Germany and the Soviet Union between the years 1918, the end of World War I, and 1941, when Germany invaded the Soviet Union. It specifically focuses on the motivations behind the Non-Aggression Pact signed by the two countries in August 1939 despite clear ideological hostility, and how and why the partnership fell apart by 1941. With the Non-Aggression Pact, Germany and the Soviet Union entered into a strange partnership, in which the two countries collaborated militarily and shared extensive resources though both governments believed a war with the other was inevitable. German-Soviet relations before and after Adolf Hitler’s rise to power is also analyzed, with special attention given to the Soviet Union’s attempts to instigate a Communist revolution in Germany following World War I. Using primary sources from within the respective governments at the time in addition to secondary sources, this paper traces the negotiations and diplomatic efforts that shaped Europe during this time period, including the deal signed between Great Britain and the Soviet Union shortly following the German invasion, marking the decisive turning point in World War II.