Remembering Operation Chastise: Special Lancasters, the No. 617 Squadron and the Dam Buster raids

Lancaster only specially formed wartime unit was No. 617 Squadron, used to attack the Ruhr Dams on the night of May 16/17, 1943

The Lancaster bomber holds a special place of affection mingled with a great deal of pride in the hearts of British and Commonwealth citizens — feelings which perhaps find their parallel in the hearts of Americans toward the B-17 Flying Fortress. Just as the Spitfire epitomized the Commonwealth’s supreme spirit of defiance in the face of seemingly irresistible defeat, so the evening sight and sound of streams of Lancasters “heading out” toward the heartland of the German Reich was the ultimate translation of a war-weary people’s will to see the Nazi military and industrial machine — the source of colossal suffering for so much of the world — battered into oblivion.

Noteworthy Lancaster only specially formed wartime unit was No. 617 Squadron, used to attack the Ruhr Dams on the night of May 16/17, 1943 during “Operation Chastise.” As told by R.S.G. Mackay in his book Lacaster in action, for this attack Lancaster Mk Is from ED serial block (23 in all) were modified to carry the cylindrical mines intended for use against these specialized targets. Bomb bay doors were removed and the rear of bays were faired in. Pylon mounts were added toward the front of the bay to carry the mines. Belt mechanisms were linked to these mounts to spin the mine before it was released. An original plan to install Ford V8 engines to drive the belt mechanism was abandoned because of their weight, in favor of using the aircraft’s undercarriage hydraulic system. Finally all mid-upper turrets were removed and faired over. Three prototypes — ED765/G, 817/G and 825/G — carried out test dropping of the mines; the latter aircraft, ED825/G, however, was not to be one of the 19 aircraft involved in what was to be a successful but costly operation.

On May 16, 1943 just short of a month after trials were conducted with the new weapon, nineteen Lancasters of No. 617 Squadron lifted off in three waves; one of nine aircraft and two of five. The first wave, of nine, led by Wing Commander Guy Gibson, was to attack the Mohne Dam and if that was breached, go on to attack the Eder Dam. If both targets of the first wave were breached, any aircraft still carrying mines were to assist the attack on the Sorpe which had been detailed to the second wave. The third wave was a mobile reserve under the direct command of No. 5 Group in England.

The Sorpe Dam was damaged, and the Mohne and Eder were breached, flooding the Ruhr Valley drowning some 1200 people and putting much of the Ruhr industry out of action. Of the 19 Lancaster B. Mk III Specials dispatched, eight failed to return. The surviving G aircraft were remodified back to standard bombers, and reissued, the Dam Buster raids were not to be repeated. No. 617 Squadron, between its operational debut and early 1945, was employed in regular pin-point bombing sorties. During this period its Lancasters were mainly standard machines, an exception being the bomb bays which were of the bulged pattern to accommodate the 12,000 lb H.C. bomb, and it’s acrodynamic off-shoot, the “TallBoy.”

Photo credit: Crown Copyright