Kramer served in the Natzweiler camp before being appointed as the commandant of Auschwitz and later Belsen. In 1945, numbers in the camp increased from 15,000 to nearly 50,000. When the camp was liberated by Allied forces at the end of the Second World War they found more than 13,000 corpses.
The commandant of Bergen-Belsen, Josef Kramer, and fourty-four others were tried by a British war crimes court at the Belsen Trial in Luneburg, Germany, from August 17, 1945, to November 17, 1945. Kramer was found guilty and sentenced to death and hanged on December 13, 1945.