As the Allies began to advance on Nazi Germany, the SS began to evacuate the first concentration camps in summer 1944. Thousands of prisoners were killed before the evacuation due to being ill or unable to walk. At the end of 1944, the overcrowding of camps began to take its toll on the prisoners. The unhygienic conditions and the supplies of food rations became disastrous. In November a typhus fever epidemic broke out that took thousands of lives.
The liberated inmates had to be kept in the camp until the typhus epidemic could be brought under control. The Americans used DDT, a new insecticide not being used in Germany, to kill the lice in the camp. When the epidemic ended, the concentration camp was immediately turned into War Crimes Enclosure No. 1 for 30,000 Germans who had been arrested as war criminals and were awaiting trial by an American Military Tribunal. Most of them were released by 1948 for lack of evidence, although some were transferred to France for trial.
In 1935 the Wehrmacht began to build a large military complex close to the village of Belsen, a part of the town of Bergen, in what was then the Province of Hanover. This became the largest military training area in Germany of the time and was used for armoured vehicle training. The barracks were finished in 1937. The camp has been in continuous operation since then and is today known as Bergen-Hohne Training Area. It is used by the NATO armed forces.