Actually Gotthard I do believe the best ( veterans of 1939-41 ) of German Army was destroyed during the autumn and winter 1941-1942. For the summer 1942 Hitler was forced to gather troops from the other axis countries ( Italy, Rumanian etc and we know how motivated they were to fight.. ) and could only start an attack in ONE Army group sector which he chose to be the Southern Army Group. I´m sure Hitler would have wanted to attack in all three AG sectors if he could have.

Also the German Army Group was almost totally wiped out in the south in Kharkow but instead the Red Army was hurt really bad when Manstein let them enter the trap . If the weather had not become so awful and the Germans had plenty of reserves I wonder how far could the Germans had attacked after Kharkow March 1943? All the way back to Stalingrad? ( A huge but an interesting what if in my opinion! ) I mean the Red Army really got beaten badly but could gather the reserves during the muddy period for the summer fighting at Kursk.

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