The Siege of Stalingrad, 1943. Hitler's Critical Error.

Germany’s failure to take Stalingrad did more than cost them a city, it collapsed the entire southern campaign. With the 6th Army destroyed and the line of advance broken, the push toward the Caucasus oil fields disintegrated. Those fields were the key to strangling the Soviet war effort, cut them off, and the Red Army’s engines would fall silent. But without Stalingrad, the route was dead. The Wehrmacht, now overextended and underfed, could not punch south. Hitler had lost the one chan...