In early April 1945, with US troops fast approaching, the Buchenwald SS began to hastily evacuate the camp, on the orders of SS leader Heinrich Himmler. In the end, it forced around 28,000 prisoners out of the main camp. But another 21,000 were left behind when US soldiers arrived on 11 April. Rumours soon spread that these liberated prisoners had committed crimes against German civilians. Such stories were generally without foundation, but after they reached Nazi leaders, Himmler acted. As the former Buchenwald commandant Hermann Pister testified on 2 July 1945 in Allied captivity, Himmler now ordered further camp evacuations.
On 15 April, 1945, around 1700 hours, I arrived with Gruf[Gruppenführer] Glücks and the Commandant of the concentration camp Sachsenhausen, SS Standartenführer Kaindl, at the special train of the Reichsführer [Himmler]. The Reichsführer asked me to give him an exact report concerning the evacuation of the prisoners from Buchenwald.
He also wanted to accuse me of the following: A few days ago the radio was supposed to have reported a statement from the Reuters news agency according to which 5,000 prisoners had escaped from the Buchenwald concentration camp; they had knocked the guards down and gone to Weimar where they had committed acts of pillaging and raped the women. I was in a position to prove that this announcement was not based on facts.
he would not withdraw this order
In order to avoid similar troubles, in other camps, he [Himmler] had ordered their evacuation and he would not withdraw this order. He was very pleased with my report and showed great confidence in the future.
He told me about the orders he had given to the effect that the prisoners of the concentration camps Flossenbürg, Mauthausen and Dachau be evacuated to a valley in Tyrol, on foot, if no […] transportation was available. Once the prisoners had arrived at this destination, they would have to build their own quarters, and if necessary, dig holes in the ground.
Source: Nuremberg documents, NO-254