In 1944, the Soviet Union made significant advances across Eastern Europe toward Germany, including Operation Bagration, a massive offensive in the Byelorussian SSR against the German Army Group Centre. In 1944 the German armies were pushed out of the Baltic states (with the exception of the Ostland), which were then re-annexed into the Soviet Union. As the Red Army reconquered the Caucasus and Crimea, various ethnic groups living in the region—the Kalmyks, Chechens, Ingushi, Karachai, Balkars, and Crimean Tatars—were accused of having collaborated with the Germans. Using the idea of collective responsibility as a basis, Stalin's government abolished their autonomous republics and between late 1943 and 1944 deported the majority of their populations to Central Asia and Siberia. Over one million people were deported as a result of the policy.