In the period following World War 1 (1914-1918), national military powers turned their attention to the design and development of "multi-turreted" tanks with thinking being that a such a configuration would be a beneficial battlefield addition in upcoming wars. The tanks were generally of the heavy classification due to their required armament, hardware and drives, embodied by such designs as the British Vickers Independent, the Soviet T-35 and the German Neubaufahrzeug.
For the British Army, their tanks of World War 1 proved ultra-critical in ending the trench warfare stalemates of the First World War and development of similar-minded machines continued despite slashed post-war budgets worldwide. Looking ahead, the Army began to consider an all-new heavy tank concept during 1924 and ordered a pilot vehicle to feature the multi-turreted approach. The design eventually earned itself the designation of "A1E1 Independent" and was constructed by the storied concern of Vickers.
Design of the Independent fell to one Walter Gordon Wilson. The approach retained the proven track-and-wheel arrangement which tied the systems to the sides of a suspended hull structure housing the crew, fuel stores and drivetrain. The engine was positioned in the rear and consisted of an Armstrong Siddeley V12 gasoline-fueled, air-cooled system developing 370 horsepower output. This was then tied to a transmission system featuring four forward speeds and one reverse. The engine exhausted through a pair of cylindrical muffler systems mounted atop the hull sides at the rear. A primary turret was nestled at the forward-center of the hull roof and mounted the then-powerful QF 3-pounder (47mm) main gun with traversal was a full 360-degrees over the hull. To this armament was added 4 x .303 caliber Vickers machine guns - however these were themselves fitted to four individual turrets at each corner of the main turret. As such, the total operating crew (including gunners) measured eight personnel - forcing an integral intercom system as standard. Armor protection was 13mm to 28mm at the various facings of the vehicle while dimensions included a length of 25 feet, a width of 8.8 feet and a height to turret top of 9 feet - a very large vehicle for the period. Weight was a hefty 34 tons.
As designed, the Independent possessed the mobility, protection and firepower required of its heavy battlefield classification. It could supply fire support, take on enemy tanks directly and break through enemy defenses while protecting its crew through armor and armament. The vehicle possessed a maximum road speed of 20 miles per hour (in ideal conditions) and an operational range of 95 miles. Cross-country travel was aided some by a coil spring suspension system though internal comfort for the crew was limited.
Upon completion and initial testing, the pilot vehicle was handed over to British military authorities in 1926 for formal evaluations. However, the project's death proved swift amidst rising costs and shrinking development budgets. As such, only the single prototype vehicle would ever be completed. It was never to see saw combat service despite the onset of another World War in Europe.
The story of the Independent did not end there, however, for the design was reportedly stolen by the Soviets which reconstituted the vehicle as their own T-28 medium tank (503 produced) and the later T-35 heavy system (61 produced). Unlike the British design, these two Soviet designs actually saw combat service heading into World War 2 (1939-1945). Additionally, British Army officer Norman Baillie-Stewart was imprisoned for five years after being convicted of selling the Independent plans to Britain's future enemy - Germany. This would explain the arrival of the 26-ton, multi-turreted Neubaufahrzeug heavy tank appearing across five examples from 1934 to 1936. However, these vehicles served more as propaganda tools for the emerging Nazi government though a few were fielded through active service during the Norway campaign of 1940.
The concept of the multi-turreted tank was eventually proven unsound, particularly in the armored warfare actions prior to, and during, World War 2. The single-turreted tank remained the undisputed king of the battlefield and was personified in such classic instances as the German Panzer types, the Soviet T-34 and American M4 Sherman. The multi-turret concept never arose as a viable battlefield implement ever again.
The sole Independent pilot vehicle completed actually survived the test of time (and the fighting of World War 2 as well as the Cold War decades) and remains a protected museum showpiece under the roof of the Bovington Tank Museum in southwest U.K. today. Physically seeing the vehicle, one immediately appreciates the size of the monstrous creation - a product of its unsettled times and, in several ways, a very influential tank design in its own right.