potential Anglo-American invasion on the Western Front in 1942 (which would not actually happen until 1944), Hitler shifted his primary goal from an immediate victory in the East, to the more long-term goal of securing the southern Soviet Union to protect oil fields vital to a long-term German war effort. The German southern campaign began with a push to capture the Crimea which ended in disaster for the Red Army, and caused Stalin to issue a broad scolding of his generals' leadership. In their southern campaigns, the Germans took 625,000 Red Army prisoners in July and August 1942 alone. Feeling the Soviets were all but defeated, the Germans then began another southern operation in the fall of 1942, the Battle of Stalingrad, which would end up marking the beginning of a turning point in the war for the Soviet Union. Although the Soviets suffered in excess of 1.1 million casualties at Stalingrad, the victory over German forces, including the encirclement of 290,000 Axis troops, marked a turning point in the war. The Soviets repulsed the German strategic southern campaign and, although 2.5 million Soviet casualties were suffered in that effort, it permitted the Soviets to take the offensive for most of the rest of the war on the Eastern Front.</ref> Without Soviet goods, from 1942 to the end of the war, German war efforts were severely hampered with Germany barely managing to scrape together enough reserves for a few more major offensives. In terms of supplies, oil was the main obstacle, with shortages in some places by the end of 1941 and forcing Germany to turn south to attempt to invade the oil-rich Caucasus in 1942. The Reich was forced to exist on a hand-to-mouth basis for oil, and the almost non-existent oil stocks completely disappeared by mid-1944 with Allied bombers concentrating on German synthetic fuel plants. For example, most German war aircraft sat idle, and air training for new pilots was cut to a mere one hour per week. Food supplies also dwindled. The envisioned 5 million tons per year that was supposed to come from occupied lands after Barbarossa never materialized. In fact, Germany managed to ship only 1.5 million tons of grain from the region in the remaining four years of the war. Germany was forced to ration its use of manganese and other materials. However, it was later able to address the severe rubber shortages it