At various times between September 1939 and April 1945, many experiments were conducted at Sachsenhausen, Natzweiler, and other camps to investigate the most effective treatment of wounds caused by mustard gas. Test subjects were deliberately exposed to mustard gas and other vesicants (e.g. Lewisite) which inflicted severe chemical burns. The victims' wounds were then tested to find the most effective treatment for the mustard gas burns.[14]