MkVIII ‘International’ Heavy Tank

This is the last of our series of videos/articles on the US Tanks of WWI, you can find all episodes here.

The MkVIII Heavy Tank holds the distinction of being the result of the first successful international co-operative tank project. Developed with input from British and American designers and engineers, intended to be equipped with British weapons and an American engine, with parts made in the US and Britain and to be assembled in France – a truly international undertaking. The MkVIII, sometimes referred to as ‘The International’ or ‘Liberty Tank’, owed its basic design to earlier British heavy tanks but a number of important changes were made.

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Port side of a MK VIII heavy tank (US National Archives)

Intended for introduction in 1919, the war ended before the MkVIII could enter service and even before its French factory had been completed. It did, however, see some production and inter-war service providing the heavy tank backbone of the US’ tank force for many years.

The design evolved from work by British Lieutenant G.J Rackham with later input from American engineer Major Herbert Alden. The MkVIII heavy was very much an evolution of the earlier British rhomboid heavy tanks but Rackham and Alden made some important improvements. Chiefly the redesigning of the tank’s sponsons which housed a pair of British 6pdr guns. While the tank was a foot narrower than its predecessors, the new folding sponsons could enabled the tank to be transported more easily by rail and to also, in theory, navigate narrow spaces. Alden patented this feature in December 1918 (US #1366550). Additionally, the commander’s ‘outlook turret’ positioned on top of the tank’s turret, which had vision slits on all four sides, was also retractable. Alden’s sponsons were hinged at the front and mounted on rolling bearings so they could pivot inwards.

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Alden’s patent for his pivoting sponson (US Patent Office)

The MkVIII directly addressed several shortcomings of earlier British heavy tanks, firstly the engine was insulated in its own compartment to prevent exhaust fumes overwhelming the crew. A new ventilation system was also added with a fan keeping fumes out of the fighting compartment. Secondly, overall visibility was improved with protected vision and revolver slits and the addition of the tank’s commander’s turret.

Another important design change was the move to longer tracks, about 5 inches in length, which required a dozen less links than the MkV. Each of the links was shallowly stamped to increase its strength. In terms of armament the MkVIII was designed as solely ‘male’ – with guns in its sponsons, not machine guns – however, with a raised tower on the tanks roof this provided positions for five machine guns in hemispherical ball mounts. Two more machine guns could be mounted in the tank’s hull doors located behind the sponsons. The ammunition for the 6pdr guns was held in a central ammunition storage box but the sponsons also had shell storage space surrounding the guns themselves.

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The MkVIII’s V12 engine (US Army Preliminary Handbook for the MkVIII)

The 37 ton tank was to be powered by an American V12 aircraft petrol engine manufactured by the Liberty company. Although a cheaper, water-cooled Liberty was eventually used in the American tanks. The British developed a similar 12 cylinder engine from Ricardo. This, in theory, produced 300 horsepower with a top speed of just over 6mph and a range of just under 40 miles. The MkVIII’s engine was moved from the centre of the tank to a separate engine compartment at the rear of the tank. This not only reduced engine heat and fumes in the fighting compartment but also made communication easier. Some sources also suggest that the MkVIII was the first tank to have an electronic intercom system.

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An officer illustrates how one of the tank’s ball mounted machine guns worked – the gun itself is an M1919 tank machine gun (US Library of Congress)

The American Preliminary Handbook for the MkVIII listed the tanks as being equipped with 7 ‘Hotchkiss .303-inch machine guns’, these are likely to be Hotchkiss Portative MkI*s popular in British service. In US service, however, the tanks were likely later equipped with the new Browning M1919 Tank Machine Guns. The tank carried 182 rounds of 6pdr ammunition and an additional 26 smoke rounds as well as 21,000 rounds of machine gun ammunition to keep the 7 machine guns fed.The tank’s armour was also increased lightly from the previous MkV, with 16mm of frontal armour and between 10 and 12mm at the sides. Less vulnerable areas had armour 6mm thick.

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A partial cutaway view of the tank (US Army Preliminary Handbook for the MkVIII)

The American MkVIIIs were initially planned to be manned by an eleven-man crew made up of a driver, commander, two gunners and two loaders to man 6pdrs, four machine gunners and a mechanic. Later crew complements probably dispensed with two of the machine gunners as the US MkVIIIs operated during the inter-war period dispensed with two of the midships machine guns. The British crew was planned to be smaller with 8-men fighting the tank, made up of a driver, commander a pair of gunners and loaders for the main guns and two machine gunners who were tasked with manning the tank’s various machine guns. Impressively the 34 feet long tank also had room for as many as 22 infantry to be transported.

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A MkVIII demonstrating its power by destroying a tree during testing (US National Archives)

As an allied collaborative project the production of parts was to be a collaborative effort. Britain was to contribute armour plate, structural frame work and armament. The American contribution was to include the automotive parts including the engine, brakes, drive sprockets, gears and transmission.

The French were largely uninterested in British heavy tanks and their primary contribution to the MkVIII project was a factory site near the village of Neuvy-Pailloux, 165 miles south of Paris, in central France. Critically located well away from the fighting on a main rail route north, through Issoudun. Construction of the impressive factory appears to have begun in early 1918, with the framework of seven long production halls and the installation of a powerplant and generators and the building of railway sidings completed before the armistice in November 1918. Production barely got underway in Britain, let alone in France. Contemporary photographs taken in January 1919, by the US Army Signal Corps show the factory with its roof in various stages of completion, its shop floors unfinished and empty and open to the elements. The factory would eventually be completed and used by the French army as an artillery park and later a maintenance depot.

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The incomplete Neuvy-Pailloux factory c.1919 (US National Archives)

The oringal plan was for the tank parts to be shipped across the channel and the atlantic through France’s western coastal ports to be shipped by rail to Neuvy-Pailloux where they would be assembled into working tanks. It was envisaged that the workforce would be made up of Chinese labourers with British and American foremen and managers.

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Inside the incomplete factory (US National Archives)

As many as 3,000 tanks were planned for 1919. The British intended to build 1,450 MkVIIIs of their own use in addition to the 1,550 to be produced for general allied use. The British tank parts were to be manufactured in Manchester, by the various workshops of the Manchester Tanks Association, and in Glasgow, by the North British Locomotive Company. Mass production in Manchester never got underway and the initial British MkVIIIs were built in Glasgow – just 24 are believed to have been built, all but six of these were scrapped almost immediately. The first American tanks were assembled by the Locomobile Company of Bridgeport, Connecticut. The American-assembled MkVIII completed acceptance trials in the spring of 1919. With the end of the war the US order was reduced from 1,500 to 100. 100 sets of hull components were bought from Britain and assembled with corresponding American parts at the Rock Island Arsenal.

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A US MkVIII at Camp Meade, c.1921 (US National Archives)

The MkVIII was the last of the British rhomboid heavy tanks. The handful of British MkVIIIs built never entered service but the 100 American tanks along with American built M1917s, MkV Heavies and Renault FTs brought back from France, formed the backbone of the US Tank Corps throughout the early inter-war period. The US MkVIIIs remained in use as training tanks until 1932. Today, just three are believed to survive; two in the US and one in Britain.


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Specifications:

Length: 34ft 2in / 10.4m

Height: 10ft 3in / 3.12m

Width: 12ft 4in / 3.75m

Weight: 37 tons

Powerplant: V12 Liberty or Ricardo engine

Speed: ~7mph / 11km

Armour: 6 – 16mm

Armament: Two QF 6pdr guns and seven .303 Hotchkiss Portative Mk1* or M1919 Browning Tank Machine Guns


Bibliography:

Preliminary Handbook of the Mark VIII Tank, US War Department, (November 1918) (source)

‘Tank’, H.W. Alden, US Patent #1366550, 25/01/1921 (source)

British Battle Tanks, World War I to 1939 – D. Fletcher (2016)

The Illustrated Encyclopaedia of Military Vehicles, I.V. Hogg & J. Weeks (1980)

The Complete Guide to Tanks & Armoured Fighting Vehicles, G. Forty & J. Livesey, (2012)

Liberty Engine: A Technical & Operational History, R.J. Neal, (2009)

Tanks: 100 Years of Evolution, R. Ogorkiewicz (2015)

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