Byelorussia (also known as the Byelorussian Soviet Socialist Republic), known today as Belarus, was a republic of the Soviet Union when World War II began. The borders of Belarus were greatly expanded in the invasion of Poland of 1939 and finalised after World War II. Following the German military disasters at Stalingrad and Kursk, a collaborationist Belorussian self-government (BCR) was formed by the Germans in order to drum up local support for their anti-Soviet operations. The Belorussian BCR 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 administrative governments from the Soviet era, and prewar public organizations including the former Soviet Belarusian Youth. The country was soon overrun by the Red Army. 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.