As winter approached and the Allies advanced, the Nazi authorities evacuated concentration camp prisoners, bringing them into camps in Germany, well away from the frontline.
The reasons for this were threefold: an attempt to hide the atrocities of the camps from the Allies; an increased need for labour in Germany; and a misguided belief by Heinrich Himmler (head of the SS) that prisoners could be used as bargaining tools with western Allies.
The SS evacuated concentration camp prisoners from both east and west on foot, and had strict orders to kill prisoners who could no longer walk. On January 18th 1945, the evacuation of Auschwitz and its satellite camps commenced. About 60,000 mostly Jewish prisoners were marched westwards, without food or water, in freezing conditions. Those who fell behind or stopped to rest were shot. They were then locked in crowded freight trains and shipped to other concentration camps further west, such as Gross-Rosen, Buchenwald, and Dachau. It is estimated that between 10,000 and 15,000 people died or were killed on this death march.
Marches occurred throughout the collapsing Third Reich, continuing until the day of the Nazi surrender; tens of thousands of prisoners perished. It is estimated that a total of 200-250 thousand concentration camp prisoners were murdered or died on the forced death marches conducted in the last ten months of World War II, over 25% of them Jews.