Molotov-Ribbentrop Pact

In late August 1939, Nazi Germany and the Soviet Union signed a ten-year non-aggression pact, stunning a world that had come to see the two regimes as bitter ideological enemies. Named for foreign ministers Vyacheslav Molotov and Joachim von Ribbentrop, the agreement cleared the way for Germany's invasion of Poland a little over a week later and, through a secret protocol, divided much of Eastern Europe into German and Soviet spheres of influence.

The pact grew out of the tense diplomacy of the late 1930s. Hitler had annexed Austria and dismembered Czechoslovakia, and the Western democracies' policy of appeasement, symbolized by the 1938 Munich Agreement, had excluded the Soviet Union from the settlement. Stalin distrusted Britain and France, suspecting they hoped to turn Germany eastward. Anglo-French military talks with Moscow in the summer of 1939 stalled, partly over whether Soviet troops could cross Polish territory, which Poland refused. Meanwhile Hitler, determined to attack Poland without risking a two-front war, offered Stalin a deal.

The agreement was signed in Moscow on the night of 23 August 1939, with Stalin present. Publicly, the two states promised not to attack one another or aid a third party that did. A secret protocol, whose existence the Soviet government denied for decades, assigned Finland, Estonia and Latvia to the Soviet sphere, and set a dividing line through Poland. Lithuania was initially placed in the German sphere, then transferred to the Soviet one in a later agreement. The protocol also noted Soviet interest in Bessarabia, then part of Romania. A separate economic arrangement sent Soviet raw materials to Germany.

The consequences were swift. Germany invaded Poland on 1 September, and Britain and France declared war. On 17 September the Soviet Army entered eastern Poland. The USSR then pressed the Baltic states into accepting military bases, fought the Winter War against Finland in 1939–40, and in 1940 annexed the Baltic states and took Bessarabia and northern Bukovina. Soviet and German authorities also cooperated in various ways in occupied Poland. Communist parties abroad, which had campaigned against fascism, abruptly shifted their line.

The partnership ended in June 1941 when Germany invaded the Soviet Union. Historians still debate Stalin's motives, with many seeing a mix of defensive calculation, buying time, and territorial ambition. The secret protocol's legacy was long: the Soviet Union admitted its existence only in 1989, after Baltic activists had made it a central issue in their independence movements. It remains a contested and emotive subject in the politics of historical memory across Europe.