'We did what we had to do': The true story of World War Two's Dambusters raid

In May 1943, a specially formed RAF squadron embarked on a daring moonlit mission – but its success came with a heavy cost. In 1976, the BBC spoke to one of the airmen who made it home alive.

Throughout the month of April 1943, Jack Buckley practised low-level night-flying and navigation for a top-secret mission as part of Royal Air Force 617 Squadron. Operation Chastise's security was so tight that no one in the hastily formed squadron – made up of 133 airmen from the UK, US, Australia, Canada and New Zealand – actually knew what they were training for. 

There was plenty of speculation, "but no one was near the truth," Buckley recalled to the BBC when he was interviewed in 1976 at RAF Scampton in Lincolnshire. "Someone had the bright idea that we might be dropping tanks in the desert, and there were other far-flung ideas [such as] going against the Tirpitz [German battleship]." Ultimately, the 617 Squadron would become known by the name of the audacious and dangerous mission they were about to embark on – the Dambusters.

At 21:28 on 16 May 1943, 82 years ago this week, the first of 19 specially modified Lancaster bombers took off for a precision raid that aimed to cripple the Third Reich's war machine. Their target was three huge dams at Möhne, Eder and Sorpe in the Ruhr region, Germany's military-industrial heartland. 

The dams were supplying water and hydro-electric power to the surrounding German factories that were manufacturing armaments. It was thought that if the dams could be destroyed, the resulting flooding would cause catastrophic damage to the Nazis' war production and morale. A plan to attack the dams had been raised earlier in the war, but, given that the flight route was heavily defended and no plane at the time could carry a bomb large enough to destroy them, the task had been considered impossible. But the aircraft that took off in May 1943 were carrying a potent new weapon – the bouncing bomb.

Codenamed Upkeep, the purpose-built explosives had been invented by aircraft engineer Dr Barnes Wallis. Wallis had realised that smaller bombs could have the required effect if they were detonated at the right place, underwater near the base of the dam. He designed a barrel-shaped bomb that could skip across the surface of water the same way a stone does when it is skimmed. This enabled the explosives to bypass the protective underwater nets which were placed around the dams to prevent torpedoes.

But for the bombs to work, they had to be dropped from the exact altitude and the right speed. A plane would need to fly low across the water at a height of just 60ft (18m) and a speed of 232mph (373kmh). This would enable the bomb to bounce until it hit the dam, where its backspin would cause it to run down the side of the dam until it reached a depth of 30ft (9m) and explode. Wallis had modelled this trajectory by skimming marbles across a bathtub filled with water in his back garden.

The weapons were still too big to fit into a Lancaster's bomb bay, so aircraft were modified so that bombs could be carried underneath, and much of the planes' armour had to be removed so that they would be light enough to fly.

The 617 Squadron bombers set off in three waves, each targeting a different dam. Buckley was in the first wave of nine planes led by the squadron's 24-year-old Wing Commander Guy Gibson. As the rear gunner in a bomber piloted by Dave Shannon, Buckley told the BBC that he remembered feeling "glad that we were on our way" as the plane took off from the runway. "We set course for the enemy coast. It was a full moon, it was almost like daylight," he said.

The dangerous mission required exceptional flying skill and precision navigation. To avoid radar, the Lancasters needed to fly at low altitudes on flight routes that weaved in and out of positions where there were known anti-aircraft guns. At least three planes were shot down when they strayed off their routes, while two others crashed because they were flying low enough to hit high-voltage power lines.

Buckley's Lancaster was one of the ones that made it to the rendezvous over the 2,000ft-long (650m) Möhne Dam. Gibson decided to take the bombing run, while the others circled, waiting for their chance. The Möhne approach was especially hazardous. Surrounded by tree-covered hills, the aircrew were exposed to flak from gunners in the towers as they dropped low across the surface of the water. When it came to Buckley's bomber's turn, four other Lancasters had already dropped their bombs, and one plane had crashed after being hit by enemy fire and the blast of its own bouncing bomb. But the Möhne Dam was still standing.

Because the Lancaster's altimeter was not accurate enough, spotlights had been installed at each end of the aircraft to tell the airmen when they were at the right height. "We circled, we had to be 60ft exactly, we had a spotlight in the nose of the aircraft and a spotlight in the tail and they converged at exactly 60ft," said Buckley. "Number five was [pilot David] Maltby, well, he dropped his weapon successfully. We were just on the run in and Gibson called us off – the dam was gone."

As the dam burst, a 30ft (10m) wave of flood water surged through the breech, sweeping away everything in its path. But Buckley did not get much time to enjoy his feeling of relief, as Gibson "ordered ourselves, [and planes piloted by] Henry Maudslay and Les Knight to go with him to the Eder Dam". 

The Eder Dam was not defended by anti-aircraft guns, but its short approach, starting with a steep dive, made it an even more challenging target. "Well, we had to come down a very steep hill, level off, get the spotlights on, get the exact height, and then put on full boost to get up the other side to get out of the valley. Very difficult," said Buckley. "Eventually we had five runs before we actually attacked and made a successful hit on the dam itself, which caused a breach."

Knight's plane followed Buckley's. Another bouncing bomb hit Eder, causing it to collapse, sending a million tonnes of water pouring into the western Ruhr valley. Only two Lancasters managed to reach the third target at Sorpe. And because the dam was constructed of concrete covered by thousands of tonnes of earth, it was able to withstand the bombs dropped on it, suffering only partial damage. 

The damage caused by the raid was widespread, with the 330 million tonnes of flood water from the breached dams spreading for some 50 miles (80km). Twelve war production factories and two power stations were destroyed, and scores more were damaged. Mines were flooded, and every bridge 30 miles (48km) below the breached Mohne Dam was swept away. Thousands of acres of farmland were swamped, with livestock drowned in the gushing waters.

But the human cost was also extensive. Estimates vary, but between 1,200 and 1,600 people were killed, the majority of whom were civilians. The casualties included 749 prisoners of war, many of whom were enslaved female labourers from Poland, Russia and Ukraine. They were based in a camp just below the Eder Dam and drowned in the flooding. Of the 19 Lancaster bombers that left that day, eight were damaged or shot down. Of the 133 aircrew, 53 were killed. Three others were captured and became prisoners of war.

George 'Johnny' Johnson, who was part of the formation that attacked the Sorpe Dam, told BBC's HARDTalk in 2018 that he remembered the bomb's inventor being devastated when he heard of the death toll of the aircrews. "Barnes Wallis burst into tears and said, 'I've killed all those young men. I'll never do anything like that again.'"

Johnson told BBC Witness History in the same year: "I still felt that what we did, we had to do to the best of our ability, but it made me realise how much other effects war has on non-combatants, the civilians, the number of people that are killed." 

The long-term strategic impact of the Dambusters raid is still hotly debated. In the aftermath of the attack, Hitler sent an army of forced labour to repair the damage, and the war production in the Ruhr Valley was resumed again within months. The dams were rebuilt in just five months, using enslaved workers working all day and all night. Hitler Youth, German troops and prisoners of war were marshalled to repair bridges and factories. Even the loss of electrical power in the region lasted for only two weeks. But the raid did mean that Hitler was forced to commit huge amounts of manpower and money to the rebuilding effort, diverting resources that could have gone to his troops fighting in the Eastern Front or shoring up the Nazi coastal defences against an Allied invasion of Europe.

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The surviving airmen of 617 Squadron were lauded as heroes on their return and the raid made front-page news. It would be later immortalised in the 1955 film The Dam Busters, starring Richard Todd and Michael Redgrave, which – along with its rousing theme tune – helped cement the attack in the UK's national folklore. 

Gibson was awarded the Victoria Cross and 33 of the airmen involved received honours for their roles in the raid, with both Johnson and Buckley being awarded the Distinguished Flying Cross. Gibson would die a year later when his plane crashed on its way back from a mission in Germany. Just 48 men out of the 133 who took part in the raid would live to see the end of the war.

"After debriefing, we went to the mess and had some food and then we started a wonderful party," Buckley told the BBC in 1976. It was a raucous celebration that lasted two days. Despite the sudden loss of so many of his comrades, there wasn't time to mourn them properly before the survivors returned to flying. "Well, this we were used to throughout the war, so we couldn't. We drank their health and that was it." 

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