On the evening of May 16th 1943, nineteen Lancasters attacked the great dams of Western Germany with a revolutionary new ''bouncing'' bomb. The crew became known as The Dambusters.
Two men from the South watched the tests in 1942 and 1943. Bob Payne lived at Chesil Beach in Dorset, where the early prototypes were put through their paces.
Ant Larkins saw some of the later tests at Reculver on the Kent coast, where the old church towers acted as marker posts for the pilots.
The pilot who led The Dambusters is remembered in a ceremony in West Malling in Kent this afternoon - 70 years to the day after the famous wartime raid. The only surviving British Dambuster George ''Johnny'' Johnson speaks to Meridian about Guy Gibson in this web exclusive.
Sir Barnes Wallis, was the engineer who designed the "bouncing bomb" that destroyed German dams in 1943 in the daring Dambusters raid.
The operation in the Ruhr valley during the Second World War, is believed to have claimed at least 1,300 lives, and 56 of the 133 man crew that flew the mission did not return.
In an interview with BBC Radio 2, Sir Barnes daughter said her father was driven to create the bouncing bomb by a sense of patriotism and belief in the importance of the "British family of nations".
Mary Stopes-Roe said: "He was not a man of war and that is often not, I think, properly understood.
"He was a man of peace but if you have to defend something you have to defend it and that's it, you do your duty."
70-years-ago today more than a hundred men flew on a mission that became known by their nickname - The Dambusters. 19 Lancaster bombers set out from RAF Scampton in Lincolnshire to attack a series of dams in Germany's industrial heartland with a newly-invented bouncing bomb.
Two of the main dams were badly damaged but despite that success eight of the aircraft were shot down and more than 50 crew killed. The bomb itself had been tested amid great secrecy in the New Forest in Hampshire and off the coast of Kent and Dorset.
In the first of three pieces, our Correspondent Derek Johnson takes a look at how this extraordinary device came into being and at the man whose genius dreamed it into being.
He speaks to Mary Stopes-Roe, the Daughter of Barnes Wallis and Bob Payne and Ant Larkins, who saw the bouncing bomb tests.
Alex Bateman - author of ''No 617 Dambusters Sqn'' - talks about the men who set out on the famous wartime raid on the night of May 16th 1943.
The men of 617 Squadron set off Seventy years ago this week on a mission which has become one of the most famous in British military history.
Next month we'll be marking one of the most famous raids in wartime history and a group of legendary airmen known as The Dambusters.
In 1943 this specially-formed unit under commander Guy Gibson attacked a series of dams in Germany in a bid to cripple the Nazi war effort, using an ingenious bomb designed to bounce along the water - a bomb tested off the coast of Kent and Dorset.
Well 70 years on there are only three Dambusters still surviving and only one in this country. His name is George ''Johnny'' Johnson.