of Greece. On 18 May 1941 Zeitzler was awarded the Knight's Cross of the Iron Cross. His greatest success came during Operation Barbarossa, the 1941 invasion of the Soviet Union. During the first two months of Barbarossa, 1st Panzer Army plunged east into Soviet territory, then moved south to the Black Sea to cut off Soviet forces in the Battle of Uman, then north to encircle Soviet forces around Kiev, then south again across the Dnieper River, and then further south to cut off Soviet forces near the Sea of Azov. Through all this strenuous campaigning, Zeitzler kept 1st Panzer Army moving smoothly and ensured that supplies arrived. In appreciation of Zeitzler, Kleist commented "The biggest problem in throwing about armies in this way was that of maintaining supplies." In January 1942, Zeitzler was made Chief of Staff to General Gerd von Rundstedt, OB West (Commander in Chief West) and commander of Army Group D. He played an important role in responding to the Allied raid on Dieppe on 19 August 1942. Chief of Staff, OKH On 24 September 1942 Zeitzler was promoted to General der Infanterie ("General of the Infantry") and simultaneously appointed Chief of the OKH General Staff, replacing Franz Halder. Hitler had been impressed by Zeitzler's optimistic and vigorous reports, and chose him over several higher-ranked and more senior officers. Albert Speer states Hitler wanted a reliable assistant who "doesn't go off and brood on my orders, but energetically sees to carrying them out." Following Zeitzler's promotion, Hitler was initially impressed with his dedication to his task and fighting spirit. In November 1942, Soviet counterattacks surrounded the German Sixth Army in Stalingrad. Zeitzler recommended that Sixth Army immediately break out and withdraw from Stalingrad to the Don bend, where the broken front could be restored. Hitler instead became enraged, overruled Zeitzler, and personally ordered the Sixth Army to stand fast around Stalingrad, where it was destroyed. Zeitzler was urged by his Army colleagues to give the breakout order himself, but refused to act in an insubordinate manner to the Commander-in-Chief. In a gesture of solidarity with the starving troops in Stalingrad, Zeitzler reduced his own rations to their level. Hitler was informed of these actions by Martin Bormann. After two weeks and the visible loss of some 12 kilos (26 pounds) in weight, Hitler ordered Zeitzler to stop the diet and return to normal rations. During early