Aktion T4 - Wikipedia
Aktion T4 (German, pronounced [akˈtsi̯oːn teː fiːɐ]) was a postwar name for mass murder through involuntary euthanasia in Nazi Germany. The name T4 is an abbreviation of Tiergartenstraße 4, a street address of the Chancellery department set up in the spring of 1940, in the Berlin borough of Tiergarten, which recruited and paid personnel ...