The German invasion of Poland began on 1 September 1939, one week after the signing of the Molotov–Ribbentrop Pact, while the Soviet invasion commenced on 17 September 1939 following the Molotov-Tōgō agreement which terminated the Nomonhan incident on 16 September 1939. Polish to Germany forces in the September Campaign: 1,000,000 soldiers 4,300 guns, 880 tanks, 435 aircraft (Poland) to 1,800,000 soldiers, 10,000 guns, 2,800 tanks, 3,000 aircraft (Germany). A comparison of both armed forces clearly indicates the problems faced by Poland. Germany had 11 tank divisions compared to Poland’s 1; four motorised divisions compared to none in Poland; and 40 infantry divisions compared to Poland’s 30. An army group led by von Rundstedt attacked from the south while another army group led by von Bock attacked from the north with large mechanised forces.