Officially, the Third Reich lasted only 12 years. The first Instrument of Surrender was signed by representatives of Nazi Germany at Reims, France on 7 May 1945. The war in Europe had come to an end. The defeat of Germany in World War II marked the end of the Nazi Germany era. The party was formally abolished on 10 October 1945 by the Allied Control Council and denazification began, along with trials of major war criminals before the International Military Tribunal (IMT) in Nuremberg. Part of the Potsdam Agreement called for the destruction of the Nationalist Socialist Party alongside the requirement for the reconstruction of the German political life. In addition, the Control Council Law no. 2 Providing for the Termination and Liquidation of the Nazi Organization specified the abolition of 52 other Nazi affiliated and supervised organisations and prohibited their activities. The denazification was carried out in Germany and continued until the onset of the Cold War.
Against the advice of many of his senior military officers, Hitler ordered an attack on France and the Low Countries, which began in May 1940. They quickly conquered Luxembourg and the Netherlands. After outmanoeuvring the Allies in Belgium and forcing the evacuation of many British and French troops at Dunkirk, France fell as well, surrendering to Germany on 22 June. The victory in France resulted in an upswing in Hitler's popularity and an upsurge in war fever in Germany.
Heinrich Himmler's Schutzstaffel (SS) took full control of the police and the concentration camps throughout Germany in 1934–35. Himmler expanded the role of the camps to hold so-called "racially undesirable elements", such as Jews, Gypsies/Romanis/Sintis, Serbs, Poles, disabled people, and criminals. The number of people in the camps, which had fallen to 7,500, grew again to 21,000 by the start of World War II and peaked at 715,000 in January 1945.