Dissolution of European judentum.

In the summer of 1944, a massive Soviet offensive in eastern Belarus ...overran the first of the major Nazi concentration camps, Lublin/Majdanek. Shortly after that offensive, SS chief Heinrich Himmler ordered that prisoners in all concentration camps and subcamps be... evacuated toward the interior of the Reich.

The evacuations of the concentration camps had three purposes:
— SS authorities did not want prisoners to fall into enemy hands...
— the SS thought they needed prisoners to maintain production of armaments wherever possible
— some SS leaders, including Himmler, believed irrationally that they could use Jewish concentration camp prisoners as hostages to bargain for a separate peace in the west that would guarantee the survival of the Nazi regime.

In the summer and early autumn months of 1944, most of the evacuations were carried out by train or, in the case of German positions cut off in the Baltic States, by ship. As winter approached, however, and the Allies reached the German borders and assumed full control of German skies, SS authorities increasingly evacuated concentration camp prisoners from both east and west on foot.



encyclopedia.ushmm.org/content/en/article/death-marches

 Death marches during the Holocaust
 
During the Holocaust, death marches (Todesmärsche in German) were massive forced transfers of prisoners from one Nazi camp to other locations, which involved walking long distances...

 en.m.wikipedia.org/wiki/Death_marches_during_the_Holocaust