Once the strategic Schwerpunkt had been identified, the attack could commence, using the concept of Kesselschlacht (“cauldron battle”). A frontal attack would immobilize the enemy while forces on the flanks would execute a double envelopment, forming a pocket called a Kessel (“cauldron”) around the enemy. Once surrounded, the opposing army, demoralized and with no chance of escape, would face the choice of annihilation or surrender.
Political dissidents, trade unionists, and Social Democrats were among the first to be arrested and incarcerated in concentration camps. Under the Weimar government, centuries-old prohibitions against homosexuality had been overlooked, but this tolerance ended violently when the SA (Storm Troopers) began raiding gay bars in 1933. Homosexual intent became just cause for prosecution. The Nazis arrested German and Austrian male homosexuals—there was no systematic persecution of lesbians—and interned them in concentration camps, where they were forced to wear special yellow armbands and later pink triangles. The goal of persecuting male homosexuals was either for reeducation—what might now be called conversion therapy—or punishment. Jehovah’s Witnesses were a problem for the Nazis because they refused to swear allegiance to the state, register for the draft, or utter the words “Heil Hitler.” As a result, the Nazis imprisoned many of the roughly 20,000 Jehovah’s Witnesses in Germany. They could be released from concentration camps if they signed a document renouncing their faith and promising not to proselytize. Few availed themselves of that option, preferring martyrdom to apostasy. Germans of African descent—many of whom, called “Rhineland bastards” by the Nazis, were the offspring of German mothers and French colonial African troops who had occupied the Rhineland after World War I—were also persecuted by the Nazis. Although their victimization was less systematic, it included forced sterilization and, often, internment in concentration camps. The fear was that they would “further pollute” and thereby diminish the race. The Nazis also singled out the Roma and Sinti, pejoratively known as Gypsies. They were the only other group that the Nazis systematically killed in gas chambers alongside the Jews. For the Roma and Sinti, too, racial pollution and their depiction as asocials was the justification for their persecution and murder.
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.