For years, British planners who sought the destruction of the Ruhr dams were faced with a seemingly insoluble problem: accuracy. In theory, a big enough bomb such as the ten-ton British Earthquake Bomb that burrowed deep underground before it exploded, might do the job. It could destroy a dam by seismic waves – a miniature localized earthquake if you would – if it was dropped from 40,000 feet. However, no bomber existed that could carry such a heavy bomb to the required height, then drop it close enough to the targeted dam.
A smaller bomb, if it went off against a dam wall at a sufficient depth, could do the job. However, the Germans were not fools, and their dams were protected by underwater torpedo nets to prevent that. Then British scientist Barnes Wallis finally figured out a solution. Bombers could be sent on a low-level raid to bounce bombs over the water’s surface and over the torpedo nets like a skipping stone until they struck the dam’s wall. When they hit the wall, the bombs would sink down along its surface, and once they reached an optimal preset depth, they would explode. The water would concentrate the blast against the dam, and result in a breach.
15. A Plan to Skip Bombs Like Stones Over the Water
The next problem for British planners to solve was just how to get a bomb to skip on the water’s surface, then sink along the dam’s inner wall after it hit it, instead of simply bouncing back. Barnes Wallis’ solution was a spinning drum filled with explosives. A bomber would fly at a low level as it approached a targeted dam above its reservoir. Once it was at the proper height and distance from the target, it would release the explosive drum, which a motor had set to spin counterclockwise.
The bomber’s speed would propel the drum and cause it to skip over the water’s surface and bounce over the protective underwater torpedo nets. Once it struck the dam, the drum’s counter-rotation, which had been imparted by the motor inside the bomber before the drum’s release, would ensure that it hugged the dam’s wall as it sank. At the proper depth, hydraulic pistols would set it off, and basic physics would take care of the rest. Barnes Wallis’ science was good and his theory was sound. Next, was to find pilots and aircrews with enough skill and courage to conduct what would be an extremely hazardous night time raid.
Arthur Harris, head of the Royal Air Force’s Bomber Command, personally selected twenty-four-year-old Guy Gibson to lead the raid against the Ruhr dams. Gibson, a capable and courageous Wing Commander who showed great promise, was ordered to form and lead a special squadron for similar missions. The unit, No. 617 Squadron, was to essentially act as an outfit of specially trained elite aerial commandos, and they were to carry out some of the RAF’s most difficult tasks.
Gibson had his aircrews train in modified Lancaster heavy bombers, fitted with a motor in the bomb bay to spin Barnes Wallis’ explosive drum. In order to properly skip atop the water’s surface, the drum had to be released at a height of precisely 60 feet. In order to determine the correct height, an ingeniously simple technique was adopted. Two spotlights were placed on the bomber’s front and rear, and they were angled so that their lights would meet at the water’s surface when the bomber was at a height of exactly 60 feet.
To figure out the correct distance from which to release Barnes Wallis’ drums to skip their to the dam walls, another ingenious solution was adopted. Each of the target dams had two towers, one on each side. So two stick marks could be placed on a bomber’s windshield. As the bomber flew in, the sticks would visually be to the outside of the dam towers and sandwich them. As the bomber drew nearer, the angle between bomber and towers would grow wider.
As seen from the windshield, the towers would “move” closer to the sticks until, at the correct distance, the sticks and towers lined up. When they did, the explosive drum could be released. Finally, on the night of May 16th, 1943, the raid was ordered to proceed, and nineteen Avro Lancaster heavy bombers of No. 617 Squadron, divided into three formations with separate assignments, took off. They flew along carefully chosen routes in order to avoid known flak concentrations, but as seen below, losses began to mount soon as the bombers reached the European coast.
To avoid detection by German radar, Guy Gibson’s Lancasters flew low, at a height of around 100 feet. One of the bombers had to abort the mission and turn back after it flew too low, struck water, and lost the explosive drum held beneath its belly. Soon thereafter, the radio on another Lancaster was damaged by antiaircraft fire, and it lost contact with its comrades and turned back. Then a third bomber was shot down. Not long afterward, a fourth went down after it struck electric pylons, and a fifth crashed when it flew into power lines. The rest pushed on to carry out the raid.
At the Mohne Dam, Guy Gibson made his attack run, then flew his bomber across the dam to draw antiaircraft fire while other Lancasters made their approaches. The next bomber was struck by antiaircraft fire, then suffered more damage from the blast of its own bomb, and crashed after its wing fell off. The third bomber was damaged by German fire, but managed to complete its attack run. Finally, after the fifth Lancaster made its run, the dam was breached.
Once the Mohne Dam was breached, Guy Gibson continued the raid with the Lancasters that still had bombs, which he led to the Edersee Dam. It was undefended, but the angle of approach necessary to carry out an attack was difficult and was made even more hazardous by heavy fog that night. After numerous aborted runs, it was finally breached. The Sorpe Dam was the hardest to breach. Unlike the Mohne and Edersee dams, which were made of concrete, the Sorpe was a huge earthen dam that absorbed the blast more easily.
In addition, a church steeple interfered with the flight path, and once it was cleared, the bombers had only a few seconds to line up on target, reach the correct height, and get within the proper distance to release their explosive drum. After numerous dry runs to make sure they had it just right, No. 617 pilots finally released their explosives. Although the drums hit the Sorpe Dam and exploded, they only inflicted relatively minor damage to the structure’s crest and failed to cause a breach.
10. The British Got a Huge Morale Boost From the “Dambusters” Raid
On the way back home after the raid, two more Lancasters of No. 617 Squadron were shot down by German antiaircraft fire. Of the nineteen bombers that had taken off on the night of May 16th, 1943, eleven began to land at RAF Scampton in the early hours of the 17th. As soon as it was light enough outside, reconnaissance airplanes took off to fly over and photograph the damage. They brought back film of breached dams and massive floods. The damage inflicted by Operation Chastise killed about 1,700 civilians, of whom roughly 1,000 were forced laborers.
The greatest impact was the loss of hydroelectric power to factories and residences in the Ruhr for a fortnight, as two power stations were destroyed and seven more were damaged. The Ruhr’s steel production in the month before the raid was 1 million tons, but it dropped to a quarter of that in the month after the raid. Coal production also declined by 400,000 tons in the month after the attack. The damage was not permanent, however, and within two months Ruhr Valley production was back to normal. The raid nonetheless boosted British morale as an impressive feat of derring-do. Guy Gibson was awarded a Victoria Cross, and No. 617 Squadron, known thereafter as the “Dam Busters”, went on to fly further successful special raids.
9. Decades Before Pearl Harbor, the British Launched History’s First Aerial Raid From the Sea
From the earliest days of aviation, navies saw the potential of airplanes and used them for reconnaissance and observation. On Christmas Day, 1914, the British Royal Navy used airplanes offensively for the first time, with aircraft carried by seaplane tenders – ships that support the operation of seaplanes. They carried seaplanes to within range of Cuxhaven, a German city on the North Sea coast near the mouth of the Elbe River that was close to a major German Imperial Navy airship, or Zeppelin, base.
Zeppelins and their potential to bomb London loomed large in British imaginations. Fears were spurred in no small part by pre-World War I apocalyptic fiction such as H. G. Wells’s The War in the Air, in which fleets of German dirigibles bombed cities around the world, and reduced them to rubble. Plans were begun for preemptive raids on Zeppelin facilities to destroy them before they began to bomb Britain. The resultant Cuxhaven Raid was the first time that air and sea power were combined to attack land targets. It was also the first step towards the creation of aircraft carriers and the projection of force inland by naval aviation.
8. A Raid That Inflicted Negligible Damage, But Still Revolutionized Warfare
The Cuxhaven Raid was not the first time that German dirigible facilities had been attacked from the air. There had been prior raids, flown by the Royal Flying Corps – the Royal Air Force’s predecessor – against Zeppelin sheds in Cologne, Friedrichshafen, and Dusseldorf. However, the RFC’s airplanes did not have enough range to reach Cuxhaven. A plan was therefore devised for ferries converted into seaplane tenders, escorted by Royal Navy cruisers, destroyers, and submarines, to carry seaplanes to the vicinity of Cuxhaven.
Nine seaplanes, each armed with three 20-pound bombs, were lowered into the water. Only seven managed to start their engines and take off. Their orders were to reconnoiter the area, and if they spotted Zeppelin sheds, to bomb them. Mist, low clouds, fog, and enemy antiaircraft fire hampered the mission. A number of facilities were identified and attacked, but the 20-pound bombs could not do much damage, and the results were negligible. However, the raid was nonetheless a proof of concept that revolutionized warfare because it demonstrated that targets on land could be attacked by airplanes launched from the sea.
The Cuxhaven Raid demonstrated the potential of sea power wedded to aircraft, but it took decades – and another world war – before that potential was fully realized. It occurred on the night of November 11th – 12th, 1940, when the British Royal Navy launched 21 obsolescent Fairey Swordfish biplane torpedo bombers from the aircraft carrier HMS Illustriousagainst Italian warships anchored at Taranto. It was history’s first naval engagement that relied exclusively upon carrier aircraft to attack heavily defended warships and was a transformational moment for the Royal Navy’s Fleet air arm.
For years before the outbreak of WWII, the Royal Navy had mulled plans to attack the Italian fleet in Taranto. It was well-positioned to sortie out and cut British supply lines across the Mediterranean, and so it had to be dealt with in case of hostilities. The best plan, codenamed Operation Judgment, called for an attack by torpedo bombers launched from an aircraft carrier. The warships anchored in Taranto were protected by torpedo nets, surrounded by barrage balloons and antiaircraft guns, and the Italians thought they were immune. As seen below, they were not.
6. A Devastated Fleet, For the Loss of Only Two Airplanes
In the weeks and days that preceded the raid on Taranto, RAF photoreconnaissance confirmed the presence of the Italian fleet and identified the location of various warships, especially the battleships. Final plans were then formed, and a strike force prepared. A first wave of twelve Swordfish biplanes, half armed with torpedoes and the other half with bombs and flares, were launched from HMSIllustrious at 9 PM, November 11th, 1940. They were followed by a second wave of nine Swordfish 90 minutes later. The first Swordfish to reach Taranto dropped illumination flares, then bombed the port’s oil storage facilities while other Swordfish launched torpedoes at the anchored battleships. The second wave arrived shortly before midnight, dropped flares, and launched torpedoes.
In less than two hours, the biplanes hit three battleships and several cruisers, and severely damaged the port’s installations, for the loss of two planes and four crewmen. The Italians lost half their capital ships that night, and the next day, they transferred the warships that had survived the raid to the greater safety of Naples. The attack on Taranto ushered in the ascendancy of naval aviation and the aircraft carrier over battleships. It was a momentous engagement that revolutionized warfare. Other navies took a keen interest in what the British had done at Taranto, and Japanese observers of the Imperial fleet, in particular, paid close attention. US Navy observers did not, to America’s detriment a year later at Pearl Harbor.
As seen above, the 1940 British attack on Taranto demonstrated that airplanes launched from aircraft carriers could devastate an anchored fleet. It was a lesson that the US Navy, with its fleet anchored at Pearl Harbor and faced with a potential adversary in Japan which possessed aircraft carriers, should have paid attention to. It failed to do so and paid the price for that failure on December 7th, 1941, when the Japanese launched a surprise attack from carriers against the US naval base at Pearl Harbor.
Early that morning, Japanese aircraft carriers that had sailed in secrecy and radio silence across the North Pacific, reached launch positions about 200 miles north of Hawaii. From their decks, naval bombers, laden with torpedoes and bombs and escorted by Mitsubishi A6M “Zero” fighters, took off to execute a strike that had been planned for nearly a year. The raid was coordinated with other attacks that day against US possessions in the Philippines, Wake, and Guam, and against the British in Singapore, Malaya, and Hong Kong. The attack on Pearl Harbor sought to cripple America’s Pacific fleet and impede US interference with planned Japanese conquests of American, British, and Dutch territories.
The Japanese raid on Pearl Harbor, which commenced at 7:48 AM local time, caught the defenders off guard. 353 warplanes, in two waves, devastated anchored American vessels. Armed with torpedoes modified for Pearl Harbor’s shallow waters, and with bombs designed to pierce thick armor, the attackers sank four battleships and damaged another four. They also sank or damaged three cruisers, three destroyers, a minelayer, and a training ship. It was a lopsided slaughter. For the loss of 29 airplanes, 5 midget submarines, and 64 personnel killed and 1 captured, the Japanese killed more than 2,400 Americans and wounded around 1,200.
In addition to twelve ships beached or sunk, the attackers damaged nine others, destroyed 160 airplanes and damaged 150 more. However, the Japanese ignored important infrastructure. They failed to destroy oil storage facilities, docks, power stations, and other installations whose destruction would have impeded the use of Pearl Harbor as a launchpad for the US war effort in the Pacific. Additionally, there were no US aircraft carriers in Pearl Harbor that day, so America’s carrier arm remained intact. That arm of the US Navy was destined to play a key role in the frustration of Japanese plans, and in the eventual doom of Japan.
The dreaded Gestapo rounded up many members of the French Resistance in northern France in late 1943 and consigned them to the Amiens Prison. Word made it out that the Germans planned to liquidate their captives, and that they would start off with a mass execution of over 100 Resistance and political prisoners on February 19th, 1944. A precision air raid to breach the prison’s walls and allow the inmates an opportunity for a mass jailbreak was requested, and the RAF’s Second Tactical Air Force drew up plans for Operation Jericho.
To find the target was the easy part of the mission. The Amiens Prison was a conspicuous building with high walls, located in an open area adjacent to the long and straight Albert-Amiens road. The hard part, in the days before smart weapons, was how to carry out the mission without too much collateral damage. How to drop the bombs in order to blast the outer walls and kill many guards, yet not destroy the prison and kill too many of the very prisoners the operation was intended to help.
Operation Jericho’s planners accepted that some or many prisoners would die in the raid. However, it was reasoned that they were slated for execution anyhow, and the risk of death in a breakout attempt was better odds than the certainty of execution. So with that grim logic, both Allied authorities in London and the French Resistance signed off on the attack. Those responsible for the mission determined that the plane most suitable for such precision work was the de Havilland Mosquito.
The raid was pushed back repeatedly because of poor weather, until finally on February 18th, 1944, just one day before the scheduled mass executions, the decision was made that it had to be now or never. Despite heavy snow and fog, eighteen Mosquitoes took off from southern England and linked up over the English Channel with Typhoon fighters that were to provide them a protective escort. The attackers flew low and took a circuitous route until they reached the town of Albert to the northeast of Amiens. They then followed the long and straight Albert-Amiens road to approach the prison from that direction.
1. A Tactical Success, But a Controversial Mission
The plan was for the first Mosquitoes to bomb and breach the Amiens Prison’s outer walls. They would be followed by other Mosquitoes, which would bomb the guard barracks and cafeteria. The raid was timed for lunchtime, to catch as many German guards as possible as they sat down for their midday meal. The raiders arrived at noon, armed with 500-pound bombs with delayed fuses to allow the Mosquitoes to fly out of the blast zone before their munitions went off. They successfully breached the outer walls, then the guardhouse was struck and destroyed. Many guards were killed, along with collateral damage to prisoners in the vicinity. Once prisoners were observed pouring out of the breached walls, the raiders departed and flew back home.
Operation Jericho was a tactical success, but the results were mixed. The bombing was pinpoint accurate by the standards of the day. The walls were successfully breached, which allowed the prisoners an opportunity for a jailbreak. At the cost of three Mosquitoes and two Typhoons, 50 Germans were killed. However, 107 of the 717 prisoners were also killed. 258 prisoners did manage to escape, but 182 were recaptured. Controversy erupted after the war when some in the Resistance denied that they had ever requested that the prison be bombed. Additionally, no evidence emerged that the Germans had planned mass executions of the Amiens prisoners.
Where Did We Find This Stuff? Some Sources and Further Reading