Belarus (then known as the Byelorussian Soviet Socialist Republic), was divided between the Soviet Union and the Second Polish Republic when World War II began. The borders of Belarus were greatly expanded in the Soviet invasion of Poland of 1939. In 1941, the country was occupied by Nazi Germany. Following the German military disasters at Stalingrad and Kursk, the collaborationist Belarusian Central Council (BCC) was formed by the Germans in order to drum up local support for their anti-Soviet operations. The BCC in turn formed the twenty-thousand strong Belarusian Home Defence (BKA), active from 23 February 1944 to 28 April 1945. Assistance was offered by the local Soviet administrative governments, and prewar public organizations including the former Soviet Belarusian Youth. The country was soon retaken by the Red Army in 1944. Devastated by the war, Belarus lost significant populations and economic resources. Many battles occurred in Belarusian and neighbouring territory. Belarusians also participated in regional conflicts. September 1939 – June 1941 The Molotov–Ribbentrop Non-Aggression Pact of August 1939 had established a non-aggression agreement between Nazi Germany and the Soviet Union, and a secret protocol described how Finland, Estonia, Latvia, Lithuania, Poland (Second Polish Republic) and Romania would be divided between them. In the Invasion of Poland of 1939 the two powers invaded and partitioned Poland, and to return the Ukrainian, Belarusian, and Moldavian territories in the North and North-Eastern regions of Romania (Northern Bucovina and Bessarabia). The Polish defense was already broken, with their only hope being retreat and reorganisation in the south-eastern region (the Romanian Bridgehead), when on 17 September 1939, it was rendered obsolete overnight. The 800,000 strong Soviet Union Red Army, divided into the Belarusian and Ukrainian fronts, invaded the eastern regions of Poland that had not yet been involved in military operations, in violation of the Soviet-Polish Non-Aggression Pact. Soviet diplomacy were protecting the Ukrainian and Belarusian minorities inhabiting Poland in view of Polish imminent collapse. Polish border defence forces (Korpus Ochrony Pogranicza) in the east (about 25 battalions) were unable to defend the border, and Edward Rydz-Śmigły further ordered them to fall back and not engage the Soviets. This, however, did not prevent some clashes and small battles, like the defence of Grodno was defended by soldiers and local population. The Soviets murdered a number of Poles, including prisoners-of-war like General Józef Olszyna-Wilczyński. Ukrainians rose against the Poles, and communist partisans organised local revolts, e.g.