The A39 Tortoise - Tank Historia

The A39 Tortoise

The appropriately named Tortoise was a British assault tank designed with the sole purpose of attacking heavily defended enemy positions. Enormous, thickly armored and equipped with a deadly gun, the vehicle would likely have succeeded in this role.

However the war ended before the Tortoise was ready, meaning it is now most famous for its appearance in video games and as a bizarre footnote in tank design.

While it may have been a formidable assault vehicle, outside of the battlefield the Tortoise was a logistical nightmare. Weighing significantly more than a King Tiger, it would have burdened British forces, unable to cross any of their bridges and drinking more petrol than even the Allies would have been comfortable with.

Clarification: depending on your definition of the term “tank”, the Tortoise may not classify as a tank. However, as the vehicle is classed as an “assault tank”, and for the sake of simplicity, the vehicle will be referred to as a tank for this article.

Contents

Build up to the Tortoise

The Tortoise is a unique vehicle, but its design criteria was not. From around 1943, the Allies became concerned with the formidable fortifications they would inevitably encounter when after invading Europe.

Positions such as the Siegfried Line were expected to be a serious issue that would have to be overcome.

Siegfried Line defenses.
The thick defenses along the Siegfried Line.

Both Britain and the United States started developing vehicles specifically designed to tackle these sorts of defenses, resulting in a class of vehicles called assault tanks.

Driving straight towards heavily defended positions, these tanks prioritised armor over everything else.

This requirement led to a number of notable tanks, such as the Excelsior and the hilariously bad Valiant. The T28 Super Heavy Tank was the US’ attempt at a tank that could fight against fortifications, and shared many similarities with the Tortoise.

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T28 at Abeerden Proving Grounds.
The T28 was essentially a mobile bunker. It weighed almost 100 tons and featured frontal armor more than 300 mm thick.

In 1943 the British company Nuffield Mechanisation & Aero Ltd. started drawing up their own plans for an assault tank. Until February 1944 they created many different designs, from the AT1 to the AT18, but eventually the War Office settled on the AT16.

Interestingly, the War immediately made an order for 25 vehicles straight from the blueprints before a prototype had even been made. They hoped the tanks could be ready by September 1945.

The Tortoise

The resulting vehicle, named Tortoise, was fine tuned for the task of assaulting fortifications. The vehicle prioritised armor.

It was a casemate design to negate the vulnerabilities of a turreted tank and to make room for its powerful gun. The casemate was made from one giant casting and gave the crew excellent protection against even the most powerful anti-tank weapons.

Tortoise first prototype.
First prototype of the mighty Tortoise.

Over the front, the armor reached a maximum of 230 mm, while the sides were covered by up to 150 mm of steel. Its almost 2 meter wide tracks were covered by a thick armor plate which ran along the entire length of the Tortoise.

Armament came in the form of a massive 32-pounder gun, which was one of the most powerful anti-tank weapons of the war.

The 32-pounder was a 94 mm gun derived from the QF 3.7-inch anti-aircraft gun, and was designed to provide better performance than the 17-pdr as used in the Sherman Firefly. It was able penetrate over 300 mm of steel with armor piercing discarding sabot rounds.

The last surviving complete Tortoise.
The Tortoise’s 32-pounder gun was able to punch clean through a Panther during tests. Image by Morio CC BY-SA 4.0.

This was more than enough to go through the front of a King Tiger.

The gun was equally capable against concrete too, which made it the ideal gun for an assault tank.

Inside the Tortoise the 32-pounder used two-piece ammunition, which was loaded by two loaders. It was situated in a large ball mount on the front of the hull. Despite lacking a turret, the Tortoise’s gun had a firing arc of 40 degrees each side, plus an elevation of 20 degrees and depression of 10 degrees.

Inside, the Tortoise actually had a very spacious fighting compartment, thanks to its enormous exterior size.

A39 Tortoise at The Tank Museum.
The Tank Museum’s Tortoise is a mild steel prototype. Image by Nilfanion CC BY-SA 4.0.

However when filled with equipment, ammunition and the crew, this space was quickly filled.

Regarding crew, there was seven. Yes, seven.

This was a commander, driver, co-driver, gunner, two loaders and a machine gunner. One the crew was located in a small turret at the rear of the fighting compartment and operated its two Besa machine guns.

Performance

As expected, all of this created a very, very heavy tank, one of the heaviest Britain has ever made.

All in the Tortoise weighed 87 tons (79,000 kg).

This would have been fine if it was powered by a suitable engine, but this was not the case. In the rear was a 600 hp Rolls-Royce Meteor, an engine that was woefully underpowered for such a task.

Even the notoriously underpowered Jagdtiger – which weighed almost 10 tons less – used a more powerful engine.

Rear of the Tortoise.
The Meteor engine was located in the rear of the Tortoise, but was seriously underpowered for the job. Image by Morio CC BY-SA 4.0.

Based on the Merlin engine used in the Spitfire, the Meteor was an excellent engine that powered some of Britain’s best tanks. However, even this 27 litre V12 was not enough for the Tortoise.

As a result, the Tortoise had a top speed of just 12 mph on road and 4 mph off-road. This is about as fast a WWI Mark I tank.

Although the Tortoise was extremely slow, it can be argued that this was acceptable due to its role as an assault tank. It was never intended to be a vehicle of mobile warfare.

Fate

Only six were built as the War Office’s order of 25 was slashed when the war ended. These six vehicles subsequently became test vehicles.

It is known that at least one was sent to Germany for trials, where it showed the impressive power of its 32-pounder gun against Germany tanks. It also turned out to be a surprisingly reliable tank and provided an excellent, stable gunnery platform.

The real problems of the Tortoise lie not with the tank, but with the logistics surrounding it. They were simply too hefty for European infrastructure.

The Tortoise was too wide to be transported by rail, and too fuel thirsty and slow to drive any significant distance on its own. Also, civilian and military bridges trembled at the mere sight of the nearly 90-ton Tort.

Tortoise during transportation.
A39 Tortoise being towed on an 80-ton trailer by two Diamond T’s during trials in BAOR, 1948

The tank had to be transported by trailer and truck, but even this method required two military haulage vehicles to pull it along.

The hulls were either cut up for scrap or sent to shooting ranges. One mild-steel Tortoise was saved and sent to The Tank Museum, Bovington in 1949. It is still there today in excellent condition. The tank was fired up and drove in 2011. It is the museum’s second heaviest tank, only beaten by the TOG 2.

Another Article From Us: The TOG 2 – Behind the Memes

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Only one other hull is known to exist. It is currently on the Kirkcudbright military training area in Scotland. It spent many years as a range target and is in poor condition.