How British Engineers Turned Ordinary Tanks Into Bunker Killers D
It is the 6th of June 1944. Somewhere on the Norman coast, a man named Unraitzia Verer Hamill presses himself flat against the cold concrete floor of his bunker and listens. Above the groan of the sea and the thunder of naval guns, he can hear the engines. Not the distant rumble of aircraft, not the churning of landing craft.
something else, something slow, deliberate, and mechanical crawling across the shingle beach towards him with the patience of an industrial machine that has never once been asked to hurry. From the slits of his fortified position, Hamill watches a shape emerge from the smoke. It has the silhouette of a tank, but something about it is wrong.
There is a long awkward apparatus trailing behind it on a tow rope. A cylindrical trailer bobbing over the stones. Then a pipe fitted to the hull like a grotesque metal proboscus swings towards his bunker. And then it fires. Not a shell, not a burst of machine gun fire, but a roaring pressurized stream of burning petroleum gel that pours through the embraasure around corners into every crevice and shadow of the fortification with the indifferent thoroughess of liquid fire.
Hamill’s position is one of thousands along the Atlantic wall. That enormous and enormously expensive chain of fortifications that Nazi Germany spent 4 years and hundreds of millions of rice marks constructing along the coast of occupied Europe. Concrete imp placements 2 m thick, interlocking fields of fire, underground passages connecting strong points designed to hold out even after encirclement.
Adolf Hitler called it impregnable. His generals with somewhat less conviction called it sufficient. And it might have been against almost any conventional assault. The problem that faced Allied planners in the years leading up to Operation Overlord was not a lack of courage, nor a shortage of men, nor even a deficiency of naval and aerial firepower.
The problem was that the weapons they possessed, the tanks, the artillery, the infantry with their rifles and their grenades had not been designed with this specific and nightmarish challenge in mind. How do you breach a wall of reinforced concrete defended by men with nothing to lose and a very great deal of steel reinforced protection? How do you take a bunker that has been built specifically to withstand the things you are capable of throwing at it? The answer, it turned out, was British engineering.
Specifically, it was the work of one of the most consequential and deliberately obscure divisions of the British Army, the 79th Armored Division, commanded by Major General Percy Hobart, and the remarkable family of specialized armored vehicles they produced. These were not elegant weapons.
They were, by any aesthetic standard, bizarre. Some breathed fire. Some carried enormous explosive charges on mechanical arms. Some thrashed the ground ahead of them with spinning chains. Taken together, they represented a systematic, methodical British solution to what had seemed an insoluble tactical problem. The Germans had a nickname for them, Hobart’s funnies, and it was not entirely wrong, but the humor drained out of it rather quickly on the 6th of June, 1944.
To understand why these machines were necessary, you need to understand the failure from which they grew. That failure had a name, and it was DEP. On the 19th of August 1942, nearly 5,000 Canadian soldiers and a thousand British commandos landed on the coast of northern France in what was called a raid, but functioned in its catastrophic way as a dress rehearsal for the invasion that would come 2 years later.
The operation was a disaster of almost incomprehensible proportions. Within 10 hours, more than half the assault force was dead, wounded or captured. The beaches were strewn with the wreckage of landing craft, and the bodies of men who never made it past the waterline. The tactical lessons of DEP were studied with the particular intensity that only genuine catastrophe can produce.
The conclusions were sobering. Standard tanks, in this case Churchill infantry tanks, had been unable to cross the shingle beach efficiently. Their tracks struggled on the loose stones. When they did reach the seaw wall, they could not climb it. When engineers attempted to blow gaps in the defenses, they were cut down by fire from positions that conventional weapons could not suppress quickly enough to make a difference.
The bunkers simply absorbed the available firepower and kept shooting. The root of the problem was what military planners call the combined arms challenge. Breaching a fortified position requires you to do several things simultaneously. Suppress the defenders, blow holes in the obstacles, get armor through those holes before the defenders recover, and then protect the engineers who are trying to do all of this.
In 1942, the Allies had no way to do these things at the same time. Each required a specialized capability that existing weapons did not provide. There were approximately eight distinct categories of obstacle and threat that any assault force landing on a defended beach would face. Mines, both anti-tank and anti-personnel, laid in patterns across the entire landing zone.
Wire obstacles designed to channel infantry into killing grounds. Concrete seaw walls and dragons teeth anti-tank obstacles. Flooded ground and ditches impossible to wield vehicles and difficult even for tracked ones. Fortified gun positions and bunkers with interlocking fields of fire, often built into existing structures or natural features.
anti-tank ditches dug specifically to stop armor advancing inland. Pillboxes covering the beach exits and behind all of this, the defenders themselves, men in hardened positions who could survive almost anything that could be delivered at range. Existing solutions failed in different and complimentary ways.
Artillery could destroy exposed positions, but could not reliably penetrate reinforced concrete without a direct hit, and the near miss accuracy required was beyond what naval gunfire or field guns could guarantee, whilst also maintaining the tempo of an assault. Bombers faced the same problem, compounded by the difficulty of hitting specific small targets from altitude.
Standard tanks could suppress open positions but were vulnerable to mines and anti-tank fire the moment they tried to advance. Infantry could clear positions but only at enormous cost in casualties and only after armor had already suppressed the defenders which brought you back to the tank problem. What was needed was something that nobody had built before.
What was needed was a tank that could do the things a tank could not do. The man responsible for solving this problem was Major General Percy Klehorn Stanley Hobart and he was by any measure an unusual choice. In 1940, Hobart had been forcibly retired from the army after clashing with his superiors.
He was difficult, demanding, and possessed of views about armored warfare that the senior establishment found inconvenient. When Winston Churchill found him, he was serving as a corporal in the Home Guard. Churchill reinstated him personally with characteristic disregard for bureaucratic opinion and gave him command of the 79th armored division with instructions to solve the problems that Depp had identified.
Hobart’s division was based primarily at various locations around southern England and the design and development work was conducted in close collaboration with the tank manufacturers and the department of tank design. The vehicle that became the foundation for most of the specialized armor was the Churchill infantry tank.
A machine that had disappointed in conventional combat, but possessed two qualities that Hobart required above all others. Mechanical reliability and a hull that could be modified. The Churchill was slow, topping out at roughly 24 kmh, and its main armament was not exceptional by 1944 standards.
But it was built like a vault with armor up to 152 mm thick on its front face. And its wide tracks gave it exceptional cross-country performance that would prove critical on soft ground. The first and arguably most important of Hobart’s machines was the AVR, the armored vehicle Royal Engineers. This was a Churchill tank with its main gun replaced by a device called the Patard, a spigot mortar of remarkable simplicity and extraordinary violence.
The Patard fired what was officially designated the 290 mm demolition bomb, though the men who used it called it with the earthy practicality of soldiers the flying dust bin, and the name requires little explanation. The projectile weighed approximately 18 kg, was roughly the diameter of a dust bin lid, and was propelled to a range of about 80 m.
At that range, it delivered an explosive charge sufficient to destroy most reinforced concrete structures outright. The effective range was short, dangerously short in that it required the vehicle to approach within the effective range of almost any weapon a bunker could bring to bear. But the result, when it worked, was absolute.
The loading mechanism of the petard was a masterpiece of wartime pragmatism. The co-driver would open a hatch in the hull, reach out with a loading tong, a device resembling an enormous pair of fireplace tongs, and physically reload the mortar from outside the vehicle in combat under fire.
This was considered an acceptable arrangement and indeed the men who did it appear to have agreed because the AVRE proved devastatingly effective and the loading procedure however alarming worked. Beyond the Patard, the AVRE could be fitted with an enormous variety of attachments. Facriers, large bundles of wooden poles roughly 2 meters in diameter that could be dropped into anti-tank ditches to create crossing points.
Box girder bridges carried on the hull and deployed mechanically. Carpet devices which unrolled a carpet devices which unrolled a mat of hessen and chestnut pailing across soft ground to allow vehicles to cross. Bobin rollers. log carpets, skid bailey bridges. The AVRE was not a single machine but a platform reconfigurable for whichever specific nightmare awaited it.
The second great machine was the Churchill crocodile and this one was terrifying in a different way entirely. The crocodile was a standard Churchill tank with its hull machine gun replaced by a flame projector, a pipe system that ran through the underside of the vehicle and connected via an armored tow rope called the link to a specialized two- wheeled trailer containing roughly 1,800 L of flame fuel.
That fuel was a thickened petroleum compound, the military equivalent of napal, pressurized in the trailer and forced through the pipe by nitrogen gas. The projector could fire this fuel as a burning stream to a range of approximately 110 to 120 m, roughly the length of a football pitch, at a rate that would exhaust the trailer’s supply in about 80 seconds of sustained fire.
80 seconds is a very long time when what is happening is that liquid fire is being poured into your position. The production figures for these vehicles are not all publicly available as some records remain classified or were destroyed. What is known is that approximately 800 Churchill crocodiles were produced during the war, though not all were converted simultaneously, and the exact number operational at any given time varied. considerably.
A VR production was similarly substantial with several hundred vehicles entering service by the time of the Normandy landings. The first major operational test of Hobart’s funnies came on the beaches of Normandy, and the contrast with DEP was stark and deliberate. The Americans, who had declined to use specialized armor beyond the swimming tanks, suffered approximately 2,000 casualties on Omaha Beach on the 6th of June alone.
The British and Canadian beaches, where the full range of Hobart’s machines were deployed, sustained significantly lower casualties, roughly 1,000 combined across Gold, Juno, and Sword, despite facing comparable levels of fortification and in some cases stronger German resistance. The AVR went in with the first waves at Sword Beach.
Avre teams from the fifth assault regiment Royal Engineers began engaging bunkers within minutes of landing. The Patard’s short range meant crews were working under direct fire, but the results justified the risk. Positions that might have held out for hours against conventional assault were reduced to rubble in minutes.
The flying dust bin fired at point blank range was capable of collapsing the entrance to an imp placement entirely, inmbing the occupants or forcing immediate surrender. The crocodiles came into their own at strong points where the defenders were in enclosed positions accessible from outside at laava and at breast during the subsequent reduction of the German Channel port garrisons.
Crocodiles worked in deliberate coordination with infantry and AVRE. The infantry would identify and suppress exits. The AVRE would blow any reinforced aperture and the crocodile would then play its projector into the opened position. The psychological effect was profound and recorded in numerous German afteraction reports that survive in the Bundes archive.
Garrison commanders noted that the appearance of a crocodile caused immediate and widespread loss of will to resist. Soldiers who had survived artillery bombardments of hours duration would surrender within minutes of seeing a crocodile deploy its flame. The operations at Waleran in November 1944 provided another demonstration.
The island controlling the approaches to Antwerp was heavily fortified and had to be taken before the port could be used. A VR teams operated in conditions of extreme difficulty, dealing with waterlogged ground and fortifications specifically designed to resist armored assault.
Records from this operation are detailed enough to confirm that in one sector three AVRE breached positions that had resisted field artillery for the better part of 2 days. What is harder to quantify and honesty requires the acknowledgement is the precise contribution of these weapons compared with all the other factors at play. Naval gunfire, air support, infantry courage, German exhaustion.
The records exist, but they capture moments, not totals. If you are finding this interesting, a quick subscribe helps more than you know. The Germans and Americans also built specialized assault vehicles, but none matched the scale or system of Britain’s approach. Germany’s Flamanza 3 had shorter range and weaker armor than the Churchill crocodile, while the massive Sturm Tiger was powerful but too expensive and fuel hungry to produce in large numbers.
The Americans modified the M4 Sherman with engineering and flamethrower equipment, but their systems lacked the crocodile’s range.
