It is 73 years ago today that wartime Britain was waking to news of an audacious raid on Germany's industrial heartland by the RAF.
In what became known as the "Dambusters" raid, 19 Lancaster bombers from 617 Squadron set out on Operation Chastise, their target being three huge dams on the rivers Mohn, Sorpe and Eder. Each of the Lancasters had been extensively modified to carry the new "bouncing bomb" designed especially for the task by Dr Barnes Wallis.
Released from a low height and already rotating, the bomb was designed to bounce along the surface of the water like a skimming stone, coming to rest against the dam wall before sinking and detonating underwater for maximum effect.
The specially selected bomber crews had been trained to fly at less than 100 feet above the water before releasing their bombs at the optimum moment, all while under attack from the ground.
Both the Mohne and Eder dams were successfully breached, pouring 330 million tons of water into the Ruhr valley, the floodwaters spreading for around 50 miles. In truth, the disruption to the German war machine was minimal, but news of the daring raid was a major boost to British morale at a time when it was sorely needed.
The bomber crews were celebrated as heroes, although the raid came at a high price, with eight of the 19 bombers shot down or damaged and 53 of the 133 aircrew killed. The leader of the raid, Wing Commander Guy Gibson, was awarded the Victoria Cross, but was shot down and killed less than 18 months later, aged just 26.
In 1955 – a decade after the end of the war – the raid was immortalised in the film "The Dam Busters", starring Richard Todd as Gibson and Michael Redgrave as Barnes Wallis, and featuring the rousing theme music, The Dam Busters March.