On August 23, 1939, in Moscow, the Soviet-German Non-Aggression Pact and the Additional Secret Protocol were signed. According to the provisions of the second point of the Protocol, the Soviet Union and Germany assumed the right to decide a new division of Poland. On October 24, 1938, German Foreign Minister Joachim von Ribbentrop, in a conversation with Polish Ambassador in Berlin Jozef Lipski, proposed that the issue between Poland and Germany to be resolved definitively, by incorporation of Danzig into Germany. Poland rejected Berlin’s claim. On September 1, 1939, Germany attacked Poland. The Polish army was defending the national territory with selflessness, but, the forces being absolutely unequal and without any outside support, they withdrew to the eastern border. On September 17, the Polish territory was invaded by numerous Soviet units. On September 27, in Moscow, the Soviet-German Friendship and Border Treaty was signed between the USSR and Germany and three secret protocols. The treaty established the border between Germany and the Soviet Union on the territory of occupied Poland. The fourth division of Poland was taking place.