The secret purpose behind this disastrous Second World War raid.
Seventy-five years after the disastrous raid on the French port of Dieppe, the real purpose of the operation is revealed.
No amount of historical research, discovery or interpretation will change the grisly facts about the raid on the French channel port of Dieppe seventy-five years ago. In just six hours, over a thousand Allied (mostly Canadian) soldiers, sailors, and airmen paid the ultimate price on August 19, 1942. About twenty-three hundred others became prisoners of war, while scores of tanks and landing craft were burned and abandoned along the chert rock beach. What British Prime Minister Winston Churchill cavalierly referred to as a “butcher and bolt” raid had ended in unprecedented horror, bitterness, and recrimination that was ruthlessly exploited by Nazi propaganda. It was a black eye for the Allied cause at this critical juncture in the war and a disaster forever ensconced in Canadian memory and psyche.
Many reasons have been given for why the raid was launched, but recently declassified documents have shown that at its heart it was a “pinch” (British slang for “steal”) operation designed to capture cryptographic material for code breakers like Alan Turing, Peter Twinn, and their colleagues at the British code-breaking centre at Bletchley Park in England. Dieppe was the fifth in a series of amphibious raids orchestrated to capture the highly sensitive material.
When these raids began in 1941, the British Empire faced the Nazi threat alone. Its survival lay in the protection of the sea
lanes that were under siege by German U-boats and surface vessels. Signals intelligence — specifically cryptography (the ability to break into and read the enemy’s enciphered communications) — rose to the forefront as a weapon. The ability to tap into German messages provided crucial information about enemy positions, plans, capabilities, technologies, and intentions, permitting the Allies to allocate scarce resources in a calculated fashion. The most sensitive intelligence came from Bletchley Park and was classified “Ultra Secret.”
The British Royal Navy, along with Combined Operations Headquarters, developed a pinch doctrine — a systematic approach or playbook — to seize enemy cipher material, such as code books, cipher tables, and even the famed German Enigma cipher machine itself.
Three forms of pinch operations emerged. The first, known as “pinch by chance,” was the incidental discovery of useful material during an action at sea or on land. The second, “pinch by opportunity,” called for a special force to be ready to take advantage of conditions created by an ongoing operation. The third was “pinch by design.” In this scenario an operation was laid on specifically to capture the precious cipher material.
The key to success lay in a multi-faceted approach underscored by three intricate pillars of success — namely, surprise, shock, and security. Surprise was paramount to reduce the odds that the enemy would destroy the material before it could be snatched. All pinch operations were underlined by this primary need, even if this meant normal levels of tactical common sense fell short.
The second pillar, shock, meant a thunderclap of firepower designed to rattle, pin, kill, or incapacitate. In this case, firepower had to be sudden and suppressive, rather than destructive — otherwise the material being sought after could be lost.
Finally, the pillar of security was needed to hide the real purpose of the raid. This was a twofold process. First, to placate German suspicion, any enemy vessels or facilities that were seized were to be reported as sunk or destroyed. Second, the raid itself was to be designed to look nothing like a pinch operation. Rather ingeniously, the British utilized the concept of disproportionate force allocation to give the appearance of an orthodox operation in order to confuse and deflect from the true intent — something Admiral John Godfrey, the head of the Royal Navy’s Naval Intelligence Division, referred to as “cracking a nut with a steam hammer.” In theory, this reasoning was sound: No enemy would ever suspect that the devotion of such large amounts of resources was merely a cover.
The first pinch by design, in the Lofoten Islands of Norway in March 1941, met with unprecedented success. Material seized instantly lifted the daunting cryptographic blackout plaguing Bletchley Park and changed the balance in the Battle of the Atlantic towards the Allied cause. Until then, the code breakers had been stymied by the daunting threerotor version of the naval Enigma machine. Then, British army commandos, supported by boarding parties from the Royal Navy, swarmed into the harbour, stormed ashore, and plundered German trawlers, the local naval headquarters, and a communications supply depot. Press reports described the “sinking” of captured vessels and the large-scale destruction of shore facilities — propaganda skilfully calculated to thrill the public and to offset German worry about the capture of cipher material.
The success of this operation put the amphibious approach to pinching on the map and was a definite feather in the cap of Combined Operations. But a dearth of specialized landing craft was problematic, and pinch operations changed form, with lone trawlers stationed far out of sight in the Atlantic becoming the main targets. In the months following the Lofoten raid, over a dozen trawlers were scooped up, providing much-needed material for the code breakers.
Meanwhile, the systematic disappearance of their weather trawlers led the German navy — the Kriegsmarine — to suspect that its three-rotor Enigma enciphered communications had been compromised. Although a change in cipher tables was the quick fix for the rest of the Kriegsmarine, the head of the U-boat arm, Admiral Karl Doenitz, took an extra step and began outfitting his Atlantic U-boats with a new four-rotor version of the Enigma. The additional rotor increased the already astronomical odds of breaking the cipher to an otherworldly ninety-two septillion to one, leaving a pinch as the “only hope.”
British naval intelligence knew something was afoot. A smashed lid from a four-rotor Enigma was pulled from a captured U-boat on August 27, 1941, providing clear evidence that a new device had been parcelled out and that another intelligence blackout was in the offing. The only saving grace at this point was that Doenitz had yet to pull the trigger on their use in combat. The introduction of a new encryption device to an entire navy was not easy or costefficient, and the British reasoned that the Kriegsmarine would not make a wholesale changeover unless convinced that the three-rotor model was permanently compromised. They were wrong.
When Lord Louis Mountbatten took command of Combined Operations in October 1941, another pinch raid on Lofoten and Vaagso islands in Norway was in the last stages of preparation. Mountbatten, the vainglorious playboy of royal bloodlines, who was said to have been promoted far above his ceiling by Churchill, possessed an unparalleled technical understanding of signals intelligence. Having designed the signals intelligence plan for the Mediterranean fleet, and having lobbied for improved encryption devices for the Royal Navy, Mountbatten understood the vital nature of cryptography.
But Mountbatten’s personality coloured the planning and the execution of future pinch raids with a distinct hubris, fuelled by his egotism, panache, and “boy’s own” flair. This left Admiral Bertram Ramsay (who later commanded all naval forces for the Normandy invasion in 1944) to opine that Combined Operations Headquarters was now in the hands of “inexperienced enthusiasts” susceptible to “victory disease.”
This phenomenon was reinforced when the twin raids on Lofoten and Vaagso islands — Operations Anklet and Archery — were carried out on December 27, 1941. From an operational point of view, these were widely considered the most successful pinch raids of all. However, although much crucial cipher material fell into Allied hands, nothing related to the four-rotor naval Enigma materialized. That setback did not phase Mountbatten or his planning staff in the slightest. For them, the raids had gone according to plan; so what could possibly go wrong moving forward, as long as they clung to their ever-expanding and increasingly bold game plan? This flawed assumption laid the groundwork for disaster at Dieppe the following summer.
The results of the latest raid thrust the British into a precarious position. With no indication as to when Doenitz would start using the new device, they were hesitant to take any action that could hasten its arrival. Yet they had to remain ready to pounce when it did.
The Naval Intelligence Division — which had learned in January that some German surface vessels operating along the French channel coast had also been outfitted with the fourrotor Enigma — realized that it was only a matter of time before the entire Kriegsmarine was using it. On February 1, 1942, Doenitz gave the go-ahead for his Atlantic U-boat fleet to begin operations with the new device. It was within the atmosphere of this potential nightmare intelligence scenario that the raid on Dieppe was conceived.
Ever ambitious, “Dickie” Mountbatten was already a step ahead. With the British Army on the defensive in North Africa and in full retreat in the Far East, his force was the only one capable of mounting an offensive operation to seize vital cipher material. Not lost on him, either, were the potential political rewards that a successful pinch raid offered for both his career and his burgeoning Combined Operations empire.
After all, Mountbatten’s political master, Winston Churchill, maintained an almost child-like fascination for the fruits of cryptography, having harnessed its power as First Lord of the Admiralty in the First World War. Capturing material leading to the defeat of the new four-rotor beast would have been akin to returning with the Holy Grail in the tribalistic world of Whitehall. Not only would it have proved Mountbatten’s doctrine and his leadership, it would have raised his shaky profile somewhat in the eyes of British chiefs of staff. In this case, Mountbatten called upon the experience of the same planning team that had engineered the Lofoten and Vaagso pinches to lay the founda-
tions for a series of amphibious raids on the French coast. The first two were planned attacks on the U-boat base and dry dock at Saint-Nazaire and the harbour at Bayonne for late March, with Dieppe third in line for mid-June.
The Saint-Nazaire raid, conducted with all the reckless daring that Mountbatten could muster, succeeded in grabbing headlines by knocking out the dry dock that could house the super-battleship Tirpitz. However, it cost an entire commando unit and failed to score the needed cipher material. At Bayonne, the entire operation was abandoned at the eleventh hour when the raiding force failed to penetrate the estuary leading to the port. But, as neither raid had ended in a costly disaster, there was nothing to press Mountbatten and his staff into a hard re-examination of pinch doctrine, and future operations like Dieppe became bigger and bolder.
By this time, the impact of the four-rotor machine was being felt, as U-boats slipped from sight in the Atlantic. As feared, a sharp spike in torpedoed Allied merchant ships and oil tankers resulted. Then came news that U-boats in the Mediterranean were using the machine. These developments had direct strategic implications for the war effort and increased the pressure in the cryptographic war. This is the moment when Admiral John Godfrey noted that Dieppe became “hot” and the planning for the Dieppe raid went into overdrive. Godfrey’s department produced a nearly eighty-page topographical report on the port and on the beaches eight kilometres to each side of the town. An outline plan, which was drawn from Godfrey’s blueprint, called for the Royal Marine Commando, the only unit tasked with a mission at this juncture, to penetrate the port, capture vessels, and wreak
havoc — all euphemistic language designed to cover the pinch.
But what made Mountbatten and British naval intelligence confident that Dieppe would deliver the goods? The French channel port had been on their radar from the time France fell, as it housed the type of vessels that utilized cutting-edge encryption machines as well as various lower-level codes and ciphers that provided “cribs” used by Bletchley Park’s code breakers. Dieppe was also a main link for Kriegsmarine communication in France and housed a communications supply depot in addition to a portside naval headquarters believed to be in a hotel called the Moderne.
From the pinch perspective, Dieppe was a target-rich environment. From an operational point of view, Dieppe was a short hop across the channel and well within the limits of a combined operation where land, sea, and air elements could be brought to bear quickly and effectively. The port was small and contained. A division-sized raiding force supported by armour could certainly overtake it. In short, it was “doable.”
In early May, the outline plan for Operation Rutter — later code-named Operation Jubilee — was adopted by the chiefs of staff. Detailed planning began following the doctrine of previous pinch operations. At first, Mountbatten balked at the idea of Canadian army participation, hoping that the entire Royal Marine Division would be chosen. Political considerations, however, held sway, and the Canadians were offered the job, which they eagerly agreed to take on.
Major General Hamilton “Ham” Roberts, who was selected to lead the ground element of the raid, had his hands tied from a planning perspective. His job was to put the plan into action. The Manitoba-born First World War veteran was viewed by the British as the “thruster” who would get the job done, no matter the cost. The Royal Marine Commando strike force led by decorated Commander Robert “Red” Ryder — he earned the Victoria Cross in the SaintNazaire raid — would still play the starring role but would work in direct co-operation with the Calgary Tanks, Essex Scottish Regiment, Royal Regiment of Canada, the Fusiliers Mont-Royal, and the Royal Canadian Engineers.
By the time the raid was finally launched on August 19, 1942 (it was postponed twice in June and July for various reasons), the plan had been streamlined based on the most optimistic interpretation of the experience gained in previous raids; but this refinement did not centre on a proper appreciation of the situation at hand. Rather, a tone of confirmation bias gave credence to Admiral Bertram Ramsay’s claim of “inexperienced enthusiasts” running the show.
Paramount was the need to get a two-hundred-and-fifty-ship raiding force across the English Channel at night without the Germans noticing. Here, Mountbatten employed a double bluff ploy. He reckoned that after the cancellation of Operation Rutter in July — the Germans had discovered the raiding force in port — a remount of the raid would be seen as so unorthodox that it would catch the Germans napping.
Likewise, the use of capital ships was discounted because their sudden appearance in the English Channel was bound to draw the interest of German reconnaissance. Anti-aircraft ships stationed in the Thames were also cut, as their appearance outside their normal area of operation would certainly pique enemy curiosity. Using heavy bombers to destroy buildings along Dieppe’s main beach was likewise scrubbed, as the drone of their engines and their radar signature would alert the defenders, as had happened at Saint-Nazaire. Perhaps most importantly, though, heavy bombing could have incinerated the material they came to capture, while filling the streets with rubble and preventing quick ac-
cess to the port by the raiding force. Suppressive strafing runs by fighter-bombers to paralyze the defenders were employed instead.
The pinch itself relied on an overly complex plan based on strict and inflexible timings — similar to a symphony where all musicians must be on time and on target for all the movements to succeed. The intent was to descend upon Dieppe like a thunderclap at dawn and to smother the port in crab-like fashion. First on the agenda were outer-flank attacks on gun batteries by British army commandos and the simultaneous capture by Canadian infantry of the daunting headlands that straddled Dieppe’s main beach and controlled the entrance and exit to the port. The South Saskatchewan Regiment, followed by the Cameron Highlanders of Canada, would capture the west headland at Pourville and then fan out southwest to throw up a cordon sanitaire — or perimeter — to prevent German counterattacks from reaching the port. To the east, the Royal Regiment of Canada, followed by the Black Watch of Canada, would land at Puys and silence the guns atop the eastern headland. From there they would co-operate with the units landing on the main beach to create a pipeline for the pinch.
Thirty minutes after the flank attacks, a battering-ram frontal assault over the main beach would commence. Supported by naval gunfire and fighter-bomber attacks designed to sow confusion amongst the defenders, the Royal Hamilton Light Infantry (RHLI), Essex Scottish, Calgary Tanks, and Canadian Engineers would storm ashore onto the main beach, push over the promenade and through German positions, and plunge into the port to overwhelm the defenders.
With the RHLI creating a cordon sanitaire past Dieppe’s distinctive beachside casino, the Engineers would blow German roadblocks in the tiny streets to allow the tanks to burst into the port. There, joined by infantry from the Essex Scottish, the Calgary Tanks would silence the trawler crews and resistance around German naval headquarters to secure the cipher material. Regardless of the outcome of this phase of the attack, the Royal Marine strike force under Ryder offshore had direct orders to barrel down the channel leading into the port, come hell or high water, and to fight to the last man if necessary to capture the desired material. Once inside the port, a special unit of the Royal Marine Commando would either fight to capture the material, if not already seized, or simply gather material for extraction.
In the midst of the fight, a special boat would be sent to remove the captured intelligence booty and take it straight to Godfrey’s personal assistant — Lieutenant Commander Ian Fleming of James Bond fame — who would be waiting on a command ship offshore. With the material in hand, Fleming was the anchorman in the relay who would return to the nearest British port in the quickest possible time. With that accomplished, the Engineers would carry out a systematic destruction of the port to hide the pinch before the entire force bolted home.
Of course, that all seemed good on paper, but the reality of the day was quite different.
A lack of proper contingencies in the plan hobbled it from the start. Although the British army commando attacks on the gun batteries to the flanks succeeded, bad luck and poor navigation caused delay, and the vital element of surprise in the fight for the headlands was lost. A massacre ensued for the Royal Regiment and Black Watch landing at Puys, and they failed to get the heights. At Pourville, a costly advance inland by the South Saskatchewan Regiment and the Queen’s Own Camerons fell short of its objective, and the men were forced to withdraw. This left both headlands overlooking Dieppe’s main beach in German hands when the frontal assault arrived.
Atorrent of deadly fire greeted the Essex Scottish, RHLI, Canadian Engineers, and Calgary Tanks as they landed. They were immediately pinned down on the beach, and the massacre began. Both the RHLI and Essex Scottish managed to get tiny elements into the town, but not enough to reach their objectives in force. Meanwhile, the Calgary Regiment’s tanks in most cases overcame the beach and seawall but were unable to reach the port and trawlers because the Engineers, who were carrying explosives, became easy targets for German gunners. With no contingency in place to remove the roadblocks, the tanks were stuck, and the pinch began to collapse.
The Royal Marine strike force then attempted to go it alone and to breech the harbour but was twice turned back by heavy fire from the headlands. Desperate, Roberts sent in the floating reserve — the Fusiliers Mont-Royal — to support the Essex Scottish, who, he believed were only metres from the trawlers and the naval headquarters. They too suffered horribly upon landing. Finally, the Royal Marines were ordered to make a third try. Following in the footsteps of the Essex S0 cottish and the Fusiliers Mont-Royal, the marines suffered the same fate. In less than six hours the raid was over, with over half of the roughly one thousand men killed losing their lives in direct pursuit of the cryptographic material.
Public relations plans had been devised well beforehand to disguise and to explain the mission, depending on the outcome. In this case they had to deal with disaster on a scale never imagined. The spin focused on the heroic exploits of Canadian, British, and other Allied servicemen, serving to blind not only the Germans but history as well. Later, excuses were offered for the raid: Dieppe was launched to test Hitler’s Atlantic Wall, to placate Stalin’s calls for a second front, to learn the lessons of amphibious operations to pave the way for D-Day, along other more conspiratorial suggestions.
In truth, the raid failed to achieve its main objective despite four desperate attempts. (The Allies finally got what they needed following a pinch by chance off a sinking U-boat on October 30, 1942, near Port Said, Egypt.) Although boldness and ingenuity were needed to solve the naval Enigma crisis, the desperation of the moment, coupled with Mountbatten’s hubristic approach, didn’t help. Given what was at stake, the risk of putting on a pinch raid was well worth taking. But certainly there should have been a less deadly way of pulling it off. In this case, they went a pinch too far.
A German Enigma cipher machine with codebooks.
Above: The bodies of Canadian soldiers of the Calgary Regiment lie on the beach in the aftermath of Operation Jubilee.
Left: Captured Canadian soldiers march through Dieppe, France. Right: Canadian soldiers, some of them wounded, arrive back in England following the failed raid.
Personnel landing craft draw away from a motor torpedo boat during the raid on Dieppe.
Lord Louis Mountbatten as head of Allied forces in Southeast Asia, circa 1944.
Dieppe Raid, by Charles Comfort.
Above: Boats docked at Dieppe Harbour, circa 1942. Below: The entrance to Dieppe’s port.