The Ohrdruf death camp reference article from the English Wikipedia on 24-Apr-2004
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Ohrdruf death camp

April 4, 1945, the Fourth Armored Division and the 355th Infantry Regiment of the 89th Infantry Division, part of General George Patton's famed Third U.S. Army, liberated the first death camp, Ohrdruf or North Stalag III, a sub camp of Buchenwald, located near Weimar.