Heinrich Himmler asks Philipp Bouhler, head of the Nazi euthanasia program Aktion T4 (Operation T4) to help him get rid of human "ballast" currently incarcerated in concentration camps. Bouhler agrees and, starting in April, Bouhler's people travel around the Reich to various concentration camps where they examine "Halflings," people with one Jewish parent, that are categorized as "asocial" by camp commandants.
Some of these are selected for transport to one of the T4 gas chamber sites. Around 2,500 people from Mauthausen, Buchenwald, Auschwitz, and Sachsenhausen are murdered in this fashion.
