July 15, 2019
By Neal S Shera
After the breakout from the Normandy hedgerows the Allies raced in all directions throughout France. The voracious competition between Patton and Montgomery pushed their forces beyond its limits. Montgomery politically outmaneuvered Patton for Market-Garden, the chance to break into Germany. Yet the British couldn’t afford to isolate the enemy forces along the coast in the run to Arnhem. This left the rest of the land north of the recently liberated port of Antwerp and the coast connected to the main German defensive lines. So General Percy Hobart and his “Funny” tanks of D-Day fame were tasked with their particular equipment and skills to help open the coast and clearing the Scheldt Estuary to open the port of Antwerp. Not only was victory required, it had to be done quickly, as the Allies couldn’t move forward without supply ships offloading in Belgium.
Although the British 79th Armored Division had several unique tank designs in its organization we will focus on the four models that were the heart of their success story. They were based on two vastly different design philosophies, the medium Sherman and the Churchill Infantry tank. Representing the Sherman faction were the Crab Flail tank and the Sherman Duplex Drive or DD tank. Meanwhile from the Churchill came the unusual Churchill Armoured Vehicle Royal Engineers, or AVRE, and the infamous Crocodile variant.
Starting with the flexible Sherman platform one model of considerable use was the Duplex Drive or ‘DD’ variant. Starting in 1940, Hungarian-born Nicholas Strausser developed a collapsible canvas screen capable of floating a medium tank. The screen worked by creating a larger volume to offset the vehicle’s weight. It also raised the freeboard, or the distance from the waterline to the top of the deck. This allowed the tank to not only float but handle some wave action. To solve the issue of propulsion, propellers were mounted on the back of the tank and connected to the rear sprocket wheels. As the tank tracks turned so did the propellers, which meant that the tank could drive up onto dry land without stopping. After D-Day several improvements were made like adding bilge pumps. These tanks made a 7 mile crossing of open water to reach South Breveland without casualties.
Equally designed for a specific task was the Sherman Mine Flailing tank, more commonly known as the Crab. It consisted of simple chains attached to a spinning metal tube mounted a safe distance in front of the tank. What separated the Crab from earlier versions of flail tanks was that the drum on it was powered by the main engine. Its 43 chains were variably controlled but could spin over 140 rpm while travelling forward at just over 1 mph. Some Crabs even had cutters on the drum to tear up barbed wire. When used in combat they often deployed 3 tanks wide in an angled formation. Two other tanks followed to replace any that were put out of action. The area around the Scheldt Estuary was one of the most heavily mined by the Germans during the war. When the threat of the German mines subsided, the Crab crews successfully resisted having their Crabs converted back into regular Shermans.
While the Sherman designs were all about maintaining forward movement for the Allies, the Churchill tanks in the Funnies were all about crushing stiff opposition. The Churchill began life as an infantry support tank. It was slow, well armored and carried weapons to deal with threats to the infantry. After 1940, when the British realized the infantry tank concept was now completely outdated, they needed a new role for this design. The Churchill did have one redeeming design feature. It’s very long track system gave the tank a surprising low ground pressure and long contact area. This meant that Churchills could cross surfaces or climb angled surfaces that no other tank could. Due to this it was ideal for use in poor terrain conditions as an assault tank clearing bunkers. To that end came the Assault Vehicle Royal Engineers or AVRE and the infamous Crocodile.
The Crocodile was a devilish plot. Like many flamethrower equipped tanks it lost its hull machine gun. Almost unique to the Crocodile was that it towed a 400 gallon fuel storage trailer behind the tank. This protected the crew from immolation far better than contemporaries with internal tanks. This also gave the tank a much larger capacity at 80 one second bursts. A side-effect of the pressurized system needing to push the fuel from the trailer to the front of the tank allowed the jet of flame to reach 150 yards, more than any other mounted system. It was truly ‘do or die’ as Germans were so abhorred by them that captured Crocodile crews were summarily executed. This design was also employed in the Korean War against Communist forces.
Strangely enough our last entry is such a successful concept that is still used by the Royal Army today. The Churchill AVRE was tailor made for clearing hardened fortifications and there were several variations. There were models that carried mine plows to clear mines buried too deep for the Crab tanks. Others had a short metal assault bridge or wooden fascine for crossing ditches. The most commonly shared characteristic was a Spigot mortar in place of the main gun. This 290mm weapon fired rounds nicknamed the “flying dustbin”. There were a variety of high explosive warheads weighing from 26 to 75 pounds with an 80 yard effective range. The AVREs also carried a sixth crewman, a demolition NCO, along with 36 pounds of other tools used by combat engineers.
All of these designs were put to the test under the worsening conditions of the Fall on the Northern European coast. The battle for the Scheldt Estuary and Walcheren in particular was one of attrition, not only against the Germans, but time. The “Funnies” performance was a major factor which helped to build up the supplies needed to fight the Battle of the Bulge and beyond. Many of the concepts pioneered by Hobart are seen in modern armies across the world and the AVRE platform is alive and well.