If scorthed earth is on the list, i will vote this...imagine the logistic nightmare of feeding a horse drawn army, as the Werhmacht was having to transport a bail of hay, 500 miles per horse per day the 40,000 used horse/cattle just in Stalingrad alone...if this isn't a voting option, perhaps Stalingrad was a bigger defeat, but even capturing Stalingrad didn't assure safe passage across the Volga, all it did was allow a landing zone on the banks of the Volga for Russian re-inforcements to continue battling...the weakness was the lack of Wehrmacht and equipment on their north flank....when Gehlen told Hitler the building of Russian forces 100 miles north of Stalingrad, and what was in store...well history is done, and the fate sealed by Hitler accusing Gehlen, and his staff of treasonis or negetive views and lies...

But logistically, Leningrad was a true target and held key points, the key to the Baltic, and re-supply routes sent to Russia from GB and the USA to archangel

bf109 Emil