The Tortoise Heavy Assault Tank (A39) was a British prototype developed during the final years of World War II as a heavily armored vehicle designed to break through fortified enemy positions. It was part of the “Assault Tank” concept, prioritizing maximum protection and firepower over mobility. Although never mass-produced, the Tortoise remains one of the most formidable and distinctive British tank designs of the era.
Weighing nearly 80 tonnes, the Tortoise was the heaviest British tank ever built. It featured extraordinarily thick armor, with frontal protection up to 228 mm, intended to withstand heavy anti-tank fire and artillery. The massive, slab-sided hull was fixed (casemate-style) without a rotating turret, simplifying production and reinforcing structural integrity.
Its primary armament was the powerful Ordnance QF 32-pounder gun (94 mm), capable of penetrating over 200 mm of armor at 500 yards using APCBC rounds. This gun gave the Tortoise exceptional anti-tank capabilities, outperforming even the American 90 mm and comparable to the German 88 mm KwK 43 used on the Tiger II. The 32-pounder was mounted in a limited-traverse mounting on the right side of the hull front, supported by a hydraulic aiming system. Secondary armament included one or two 7.92 mm Besa machine guns, located in a small turret on top and coaxially with the main gun.
The Tortoise was powered by a Rolls-Royce Meteor V12 petrol engine, producing 600 horsepower, giving it a maximum road speed of just 19 km/h (12 mph). This low speed, combined with its massive weight and size (over 10 meters long with gun), severely limited its mobility and transportability. It used torsion bar suspension with six road wheels per side, providing reasonable cross-country performance for its class, but it struggled on soft ground and required heavy engineering support.
Crewed by 7 men, including a driver, commander, gunner, loaders, and radio operators, the Tortoise had a spacious interior but was complex and maintenance-intensive.
Only six prototypes were built by 1947, with limited post-war trials revealing both its impressive firepower and severe practical limitations. The end of the war and shift toward more mobile warfare doctrines rendered the concept obsolete.
One surviving Tortoise prototype is fully operational and is preserved at The Tank Museum in Bovington, occasionally demonstrated during public events.
