also launched Operation Gallop south of Star, pushing the Wehrmacht away from the Donets, taking Voroshilovgrad and Izium, worsening the German situation further. By this time Stavka believed it could decide the war in the southwest Russian SFSR and eastern Ukrainian SSR, expecting total victory. The surrender of the German 6th Army at Stalingrad freed six Soviet armies, under the command of Konstantin Rokossovsky, which were refitted and reinforced by the 2nd Tank Army and the 70th Army. These forces were repositioned between the junction of German Army Groups Center and South. Known to the Soviet forces as the Kharkov and Donbas operations, the offensive sought to surround and destroy German forces in the Orel salient, cross the Desna River and surround and destroy German Army Group Center. Originally planned to begin between 12 and 15 February, deployment problems forced Stavka to push the start date back to 25 February. Meanwhile, the Soviet 60th Army pushed the German Second Army's 4th Panzer Division away from Kursk, while the Soviet 13th Army forced the Second Panzer Army to turn on its flank. This opened a breach between these two German forces, shortly to be exploited by Rokossovsky's offensive. While the Soviet 14th and 48th Armies attacked the Second Panzer Army's right flank, making minor gains, Rokossovsky launched his offensive on 25 February, breaking through German lines and threatening to surround and cut off the German Second Panzer Army and the Second Army, to the south. Unexpected German resistance began to slow the operation considerably, offering Rokossovsky only limited gains on the left flank of his attack and in the center. Elsewhere, the Soviet 2nd Tank Army had successfully penetrated of the German rear, along the left flank of the Soviet offensive, increasing the length of the army's flank by an estimated . While the Soviet offensive continued, Field Marshal von Manstein was able to put the SS Panzer Corps – now reinforced by the 3rd SS Panzer Division – under the command of the 4th Panzer Army, while Hitler agreed to release seven understrength panzer and motorized divisions for the impending counteroffensive. The 4th Air Fleet, under the command of Field Marshal Wolfram von Richthofen, was able to regroup and increase the number of daily sorties from an average of 350 in January to 1,000 in February, providing German forces strategic air superiority. On 20 February, the Red Army was perilously