Long before the Ruhr dams raid, Operation ‘Chastise’, took place on 16-17 May 1943, the Sorpe dam — six miles south-west of the Möhne — had been identified as a critical target for RAF Bomber Command. However, it did not feature prominently in arguments for use of Barnes Wallis’s ‘bouncing bomb’. Nor did it appear in the film The Dam Busters, so its significance has been largely unrecognised. Albert Speer, Reich minister for armaments and war production in May 1943, believed this a grave error.
With war looming, plans were advanced in 1937 for a decisive aerial assault on the Ruhr manufacturing complex, where — as one Air Ministry estimate put it — an estimated “75-80 per cent of the war industries of Germany are situated”. A proposal to bomb 45 power stations and coking plants to undermine the Ruhr’s military production capacity was countered by a contention from the air targets sub-committee of the Committee of Imperial Defence that the same result could be achieved by breaching just two dams: the Möhne and Sorpe. Processes like steel production would quite literally grind to a halt with a loss of water supplies from their adjacent reservoirs.