The German offensive cost the Red Army an estimated 90,000 casualties. The house-to-house fighting in Kharkov was also particularly bloody for the German SS Panzer Corps, which had suffered approximately 4,300 men killed and wounded by the time operations ended in mid-March. At the start of 1943, the German Wehrmacht faced a crisis as Soviet forces encircled and reduced the German Sixth Army at Stalingrad and expanded their Winter Campaign towards the Don River. On 2 February 1943 the Sixth Army's commanding officers surrendered, and an estimated 90,000 men were captured by the Red Army. Total German losses at the Battle of Stalingrad, excluding prisoners, were between 120,000 and 150,000. Throughout 1942 German casualties totaled around 1.9 million personnel, and by the start of 1943 the "Wehrmacht" was around 470,000 men below full strength on the Eastern Front. At the beginning of Operation Barbarossa, the "Wehrmacht" was equipped with around 3,300 tanks; by 23 January only 495 tanks, mostly of older types, remained operational along the entire length of the Soviet–German front. As the forces of the Don Front were destroying the German forces in Stalingrad, the Red Army's command ("Stavka") ordered the Soviet forces to conduct a new offensive, which encompassed the entire southern wing of the Soviet–German front from Voronezh to Rostov. On 2 February, the Red Army launched Operation Star, threatening to liberate the cities of Belgorod, Kharkov and Kursk. A Soviet drive, spearheaded by four tank corps organized under Lieutenant-General Markian Popov, pierced the German front by crossing the Donets River and pressing into the German rear. On 15 February, two fresh Soviet tank corps threatened the city of Zaporizhia on the Dnieper River, which controlled the last major road to Rostov and housed the headquarters of Army Group South and "Luftflotte 4" (Air Fleet Four). Despite Hitler's orders to hold the city, Kharkov was abandoned by German forces and the city was recaptured by the Red Army on 16 February. Hitler immediately flew to Manstein's headquarters at Zaporizhia. Manstein informed him that an immediate counterattack on Kharkov would be fruitless, but that he could successfully attack the overextended Soviet flank with his five Panzer Corps, and recapture the city later. On 19 February Soviet armored units broke through the German lines and approached the city.