On 16 May, 1943, 19 specially modified Royal Air Force Avro Lancaster bombers of 617 squadron, crewed by a hand picked group of 133, took off carrying revolutionary bombs on a mission to destroy the impregnable Möhne, Edersee and Sorpe dams in central Germany. The mission, bomber modifications and “Upkeep” bomb were the brainchild of British aeronautical engineering genius Barnes Wallis (picture on left), who believed destroying the dams would reduce the Reich’s industrial capability, especially around steel production (a key strategic resource). 617 Squadron is still known as “The Dambusters” in honor of this mission.
The six hour night mission involved flying at tree top level over the most heavily defended stretches of German airspace (for which the crews had specially trained for weeks). On the surface, the results were spectacular – two of the three dams were breached, with significant flooding and destruction downstream. The cost was heavy – 8 of the 19 aircraft were destroyed, with some 1600 people killed (including British aircrew, and in the valley below Germans and a large group of mostly Soviet and other slave labourers). Compared to other bombing efforts of the day, the results were very impressive – compare this to the second Schweinfurt raid by the US 8th Army Air Force, where more than 600 airmen along with an unknown number of civilians (as stray bombs scattered over the city) were killed, for little to no military outcome.
Chastise had a strong effect on the theory of air power (similar to the effect the battle of Taranto had on theories of air power over the sea). It became obvious that important strategic targets could be effectively targeted by a small group of technologically sophisticated aircraft using the correct flight profiles. 617 Squadron shifted from using the large Lancaster to the much smaller Mosquito as they developed low level high accuracy attacks; and in the US, planners started to think about how to achieve strategic goals by marrying advanced aircraft that could fly singly or in small groups to weapons of dramatically increased destructive power (a problem that was solved by the development of the Hydrogen bomb, and ended with the development of the F-117A).
Like many actions during the war, the strategic value of Operation Chastise is still not well understood to this day. Due to a massive re-routing of construction and civil engineering effort by the Reich to repair the dams (they were back in operation within five weeks), there was no significant reduction in steel production as Wallis had hoped. However, those laborers would have been used in strengthening coastal defenses on the Northern French coast, so some historians argue that this led to a reduction of defenses during Operation Overlord which took place one year later, spelling the beginning of the end of the Reich.
Watch a documentary of the raid: