And without Lend-Lease, the Russians wouldn't have been able to slow the German advance on Moscow making Stalingrad a moot point. The German Army was developing radical new technologies and weapons and with no Eastern threat would have been far more likely to complete their projects. They were pursuing the atomic bomb, as well. Let's not delude ourselves into thinking that conquering Russia would not have emboldened the Austrian corporal to think America was out of reach. The German U-boats were patrolling our coast lines already.