of relief attempts, codenamed Operation Konrad, was launched during the 46-day-long Siege of Budapest. After the failure of Konrad III, the 6th Army was made part of "Army Group Balck" (Armeegruppe Balck). This army group fell back to the area near Lake Balaton. Several units, including the III Panzer Corps, took part in Operation Spring Awakening, while the rest of the Sixth Army provided defence for the left flank of the offensive, in the region west of Székesfehérvár. After the failure of the offensive, the army held the line until the Soviet Vienna Offensive on 16 March 1945. This offensive tore a gap in the 6th Army between the IV SS Panzer Corps and the 3rd Hungarian Army (subordinated to Balck's command), shattering the formation. By the end of March 1945, the 6th Army was retreating towards Vienna. It surrendered to the U.S. Army on 9 May 1945. Structure (as of October 1944) IV Panzer Corps LXXII Army Corps III Panzer Corps Hungarian II Army Corps Hungarian Group Flnta Army Reserve War crimes Bila Tserkva massacre Soon after the beginning of Operation Barbarossa, the Sixth Army's surgeon, the staff doctor Gerhart Panning, learned about captured Russian expanding bullets by using Jewish POWs. To determine the effects of this type of ammunition on German soldiers, he decided to test them on other human beings after asking SD member and SS-Standartenführer Paul Blobel for some "guinea pigs" (Jewish POWs). In July 1941 while conducting operations in Right-bank Ukraine, the Sixth Army bloodlessly captured the Ukrainian town of Bila Tserkva. Immediately after the town's capitulation, Sixth Army police units separated the Jewish population of the town into a ghetto and required that they wear the Star of David as identification. Two weeks after the occupation, members of Einsatzgruppen marched the Jews out of the town, 800 men and women in all, to be shot. The Sixth Army provided logistical support for this massacre, providing drivers, guards, weapons and ammunition. Afterwards ninety children aged twelve and under were left, their parents having been killed the night before. A staff officer with the division that made the town their headquarters wrote of their conditions: Groscurth himself sought out the district commander and insisted that the execution must be stopped. Sixth Army headquarters was faced with a decision on what to do with the children left behind now that their parents had been murdered. The division