As the nation prepares to mark the 70th anniversary of the daring and innovative Dambusters raid, a retired fighter pilot has revealed the true extent of the damage the mission caused to Nazi Germany.
Clive Rowley, a former commanding officer of the RAF's prestigious Battle of Britain Memorial Flight (BBMF) turned aviation historian and author, said the military and strategic significance of destroying three dams in the industrial heartland of Germany in 1943 has only just been realised.
The 133 men who went on the mission in 19 aircraft, 56 of whom did not return, were also incredibly courageous and skilful in carrying out the daring low flights, he said.
The mission was launched from RAF Scampton, near Lincoln by 617 Squadron.
At the time it was hailed as an incredible success even with the loss of life, but for decades afterwards its effects were downplayed or even condemned as a waste of resources by a succession of historians.
Now, extensive research carried out by retired Squadron Leader Mr Rowley suggests that the loss of water caused by the dams' destruction had a far greater effect than many realised even at the time - from making firefighters powerless to put out the flames of British incendiary bombs to cutting vital German steel production due to a lack of water for cooling.
The cost of repairing the damage caused by 617 Squadron's raid ran to the equivalent of £5.9 billion in today's money and 7,000 workers who would otherwise have been building the Atlantic Wall to prevent the D-Day landings had to be called away to fix the ruined dams.
It was an economic disaster for the Third Reich that diverted significant resources away from Germany's war effect at a critical point during the conflict.
Mr Rowley said: "In that sense it was truly militarily important, strategically important, and I think that is more modern research that has uncovered that and hasn't been widely recognised until now."