Action 14f13, also called "Sonderbehandlung (special treatment) 14f13" and Aktion 14f13, was a campaign by Nazi Germany to terminate Nazi concentration camp prisoners. Also called invalid or prisoner euthanasia, the campaign culled the sick, elderly and those deemed no longer fit for work, from the rest of the prisoners in a selection process, after which they were killed.[1] The Nazi campaign was in operation from 1941 to 1944 and later covered other groups of concentration camp prisoners.[2]