Hitler's invasion of the Soviet Union worked against him in that it opened a second front with a massive world power and diverted his focus away from the west and instead split his military in 2 also The lack of infrastructure which on a map was portrayed as massive roads(Russia wanted to seem advanced so faked large roads on maps) caused slow downs and horrible convoy of supply to German soldiers causing massive causalities not seen before by the German army. Also in invading the soviet union he lost a possible ally since before this Stalin respected Hitler and was willing to work along side him
