Allied air superiority became a significant hindrance to German operations during the later years of the war. By June 1944 the Western Allies had complete control of the air over the battlefield and their fighter-bomber aircraft were very effective at attacking ground forces. On D-Day the Allies flew 14,500 sorties over the battlefield area alone, not including sorties flown over north-western Europe. Against this on 6 June the Luftwaffe flew some 300 sorties. Though German fighter presence over Normandy increased over the next days and weeks, it never approached the numbers the Allies commanded. Fighter-bomber attacks on German formations made movement during daylight almost impossible. Subsequently, shortages soon developed in food, fuel and ammunition, severely hampering the German defenders. German vehicle crews and even flak units experienced great difficulty moving during daylight.[g] Indeed, the final German offensive operation in the west, Operation Wacht am Rhein, was planned to take place during poor weather to minimize interference by Allied aircraft. Under these conditions it was difficult for German commanders to employ the "armoured idea", if at all.
Up to this point, Auschwitz accounted for only 11 percent of the victims of the 'Final Solution'. However, in August 1942, planning began for the construction of four large-scale gassing facilities. It appears from the plans that the first two gas chambers were adapted from mortuaries which, with the huge crematoria attached to them, were initially intended to cope with mortalities amongst the slave labor force in the camp, now approaching 100,000 and subject to a horrifying death rate. But from the autumn of 1942, it seems clear that the SS planners and civilian contractors were intending to build a mass-murder plant.
Schindler grew up in Svitavy, Moravia, and worked in several trades until he joined the Abwehr, the military intelligence service of Nazi Germany, in 1936. He joined the Nazi Party in 1939. Prior to the German occupation of Czechoslovakia in 1938, he collected information on railways and troop movements for the German government. He was arrested for espionage by the Czechoslovak government but was released under the terms of the Munich Agreement in 1938. Schindler continued to collect information for the Nazis, working in Poland in 1939 before the invasion of Poland at the start of World War II. In 1939, Schindler acquired an enamelware factory in Kraków, Poland, which employed at the factory's peak in 1944 about 1,750 workers, of whom 1,000 were Jews. His Abwehr connections helped Schindler protect his Jewish workers from deportation and death in the Nazi concentration camps. As time went on, Schindler had to give Nazi officials ever larger bribes and gifts of luxury items obtainable only on the black market to keep his workers safe.