Germany and Europe as a whole was almost totally dependent on foreign oil imports.[129] In an attempt to resolve the shortage, in June 1942 Germany launched Fall Blau ("Case Blue"), an offensive against the Caucasian oilfields.[130] The Red Army launched a counter-offensive on 19 November and encircled the Axis forces, who were trapped in Stalingrad on 23 November.[131] Göring assured Hitler that the 6th Army could be supplied by air, but this turned out to be infeasible.[132] Hitler's refusal to allow a retreat led to the deaths of 200,000 German and Romanian soldiers; of the 91,000 men who surrendered in the city on 31 January 1943, only 6,000 survivors returned to Germany after the war.[133]