September 28, 1939: The fourth partition of Poland

Paradoxically, it was the German-Soviet arrangement of September 28, 1939 that caused the defeated Germany in 1945 to lose, under the terms of the Potsdam Conference, the territories east of the Oder and Lusatian Neisse rivers. Joachim von Ribbentrop's two visits to Moscow, one in August and the other in September 1939, were part of a sinister tradition of targeted cooperation against Poland of the Republic's two powerful neighbors. The first of these resulted in a pact of of non-aggression, the secret protocol of which made the pact essentially a pact of aggression - as it gave the green light for a German attack on Poland. Act two came during another visit by the head of Nazi diplomacy to Moscow, when a German-Soviet treaty on friendship and borders was concluded. This treaty was essentially another fourth partition of Poland. The subsequent course of events, moreover, meant that the Republic never again returned to its former eastern provinces.