Once Germany took over Poland in 1939, it created forced-labor camps. Thousands of prisoners died from working conditions, exhaustion, and starvation. After the outbreak of World War II, the number of concentration camps increased exponentially. The number of prisoners of war camps also rose, but after the first years of the war most were converted into concentration camps. Nazis forcibly relocated Jews from ghettos to concentration camps.
Other historians wrote that blitzkrieg was an operational doctrine of the German armed forces and a strategic concept on which the leadership of the Third Reich based its strategic and economic planning. Military planners and bureaucrats in the war economy appear rarely, if ever, to have employed the term blitzkrieg in official documents. That the German army had a "blitzkrieg doctrine" was rejected in the late 1970s by Matthew Cooper. The concept of a blitzkrieg Luftwaffe was challenged by Richard Overy in the late 1970s and by Williamson Murray in the mid-1980s. That the Third Reich went to war on the basis of "blitzkrieg economics" was criticised by Richard Overy in the 1980s and George Raudzens described the contradictory senses in which historians have used the word. The notion of a German blitzkrieg concept or doctrine survives in popular history and many historians still support the thesis.
By July 1944, Germany was losing the war; the SS began closing down the easternmost concentration camps and deporting the remaining prisoners westward. Many were killed in Auschwitz and the Gross-Rosen concentration camp. Schindler convinced SS-Hauptsturmführer Amon Göth, commandant of the nearby Kraków-Płaszów concentration camp, to allow him to move his factory to Brněnec in the Protectorate of Bohemia and Moravia, thus sparing his workers from almost certain death in the gas chambers. Using names provided by Jewish Ghetto Police officer Marcel Goldberg, Göth's secretary Mietek Pemper compiled and typed the list of 1,200 Jews who travelled to Brünnlitz in October 1944. Schindler continued to bribe SS officials to prevent the execution of his workers until the end of World War II in Europe in May 1945, by which time he had spent his entire fortune on bribes and black market purchases of supplies for his workers.