This was to be carried out by Army Group South commanded by General Gerd von Rundstedt , attacking from German Silesia and from the Moravian and Slovak border : General Johannes Blaskowitz 's 8th Army was to drive eastward against Łódź ; General Wilhelm List 's 14th Army was to push on toward Kraków and to turn the Poles ' Carpathian flank ; and General Walter von Reichenau 's 10th Army , in the centre with Army Group South 's armor , was to deliver the decisive blow with a northeastward thrust into the heart of Poland .