On the night of 16/17 May 1943, Operation Chastise used bouncing bombs designed by Barnes Wallis to breach the Eder and Möhne dams and to interrupt industry in the Ruhr valley.The Sorpe dam was damaged but not breached.
Led by Wing Commander Guy Gibson, 617 Squadron was formed, equipped and trained at RAF Scampton specifically for the operation.
Eight of the nineteen aircraft taking part failed to return.
53 airmen were killed, three became prisoners of war. On the ground 1294 were killed, including 859 in the town of Neheim-Hüsten downstream of the Möhne Dam.