Aktion Erntefest (German for "Operation Harvest Festival") was the action by the SS to liquidate all the remaining Jews in the Lublin District and the Lublin Ghetto of the General Government. The operation took place over between November 3-4, 1943. Up to 42,000 Jews were eventually killed during the Aktion Erntefest.
Read more about Aktion Erntefest: Background, Killings