Mark VIII (tank)

From Wikipedia, the free encyclopedia

Mark VIII Liberty

General characteristics
Crew	12 or 10
Length	34 ft 2 in / 10.42 m
Width	12 ft 4 in/ 3.76 m
Height	10 ft 3 in / 3.13 m
Weight	37 t
Armour and armament
Armour	16 mm
Main armament	two 57 mm L/23 guns
Secondary armament	seven 7.92 mm Hotchkiss machine guns or five M1917 Browning machine guns
Mobility
Power plant	V-12 Liberty or V-12 Ricardo 300 hp (323 kW)
Suspension	unsprung
Road speed	5.25 mph / 8.45 km/h
Power/weight	8.1 hp/tonne
Range	89 km

The Mark VIII or Liberty was an Anglo-American tank of the First World War.

1 Early Development
2 International Tank
3 Description
4 Production
5 Mark VIII*
6 Operational history
7 See also

[edit] Early Development

As the First World War progressed, the industrial production capacity of the Entente was taxed to the limit. Of the Allies, only Great Britain and France had been major industrial nations in 1914 and the latter had lost 70% of its heavy industry when the Germans overran that part of Lorraine that they hadn't already occupied in 1871. The output in Britain was limited by labour shortages and a rocketing national debt.

When the United States of America declared war on Germany on 6 April 1917, many in Britain hoped this event would solve all these problems. The two men directly responsible for British tank production, Eustace Tennyson d'Eyncourt and Lieutenant-Colonel Albert Gerald Stern, considered at first sending a delegation to the States immediately, to convince the new ally to start production of a British tank design. After some reflection they decided it was best to leave the initiative to the Americans. In June 1917 the first American approaches were made, but not by the US Army as they had expected. The US Navy wanted the most modern tanks for its US Marine Corps. At that moment the current British tank project was the Mark VI. It was (obviously) designed with existing British industrial capacity in mind. The Americans should however be able to produce a much more powerful vehicle. Stern therefore pretended that an even more advanced project had already been in existence which he called the Mark VIII (there was also a much more conventional Mark VII project). He invited the Americans to participate and contribute as much as they would like to its design. Quite impressed by British hospitality and magnanimity the delegation returned to the States. The Navy was on the brink of sending a team of engineers to Britain when the American Ministry of War was informed of developments by the US Military Attaché in London. It ordered the project to be shifted to the Army and selected Major H.W.Alden to go to the UK to work with the design team at Dollis Hill on the first drawings of the new tank. He arrived in London on the 3rd October, to discover that a lot of design work had already been done by Lieutenant John G. Rackam, mainly influenced by the dismal conditions then encountered at the battlefield in Flanders.

[edit] International Tank

The US Army had set up headquarters in France. It decided to form its own Tank Corps with 25 tank battalions including five Heavy Tank Battalions. To equip the heavy units Major James A. Drain ordered 600 Mark VI tanks in October 1917. It tried to convince the Ministry of War to divert all available tanks to the Army, leading to a conflict with the Navy (the first of many to come over this issue). This posed serious problems for the British government. It now seemed that American involvement in the war would mean a lesser number of tanks available for the British forces. Also on the 4th February 1917 binding agreements had been made with the French about tank production. These had to be renegotiated.

The man to solve all these problems was again Albert Stern. Winston Churchill, the new Minister of Munitions, had just been forced to fire Stern as director of the Mechanical Supply Department because of his mistakes in handling the Mark IV project, leading to enormous production delays. He now appointed him International Commissioner for Mechanical Warfare. Stern went to France to meet the French Minister of Munitions, Louis Loucheur and the American C-in-C John Pershing. Loucheur made it clear from the beginning that France had nothing to offer in terms of existing production facilities. Even the French Renault FT-17 light tank could only be produced because of deliveries of British armour plate. This came as no surprise to Stern who had already prepared an International Plan of ten points (in fact a bilateral agreement between the USA and Britain) that he now managed to get accepted by the Americans and was submitted to Churchill on the 11th November. Its main points included (using the original terminology):

The incorporation of a partnership between the USA and Great Britain for the production of 1500 heavy tanks to be erected in France.
The supply of a number of these tanks to France to further the higher purpose of Allied unity, should she require them (Britain hoped France would produce its own Char 2C in sufficient numbers, Loucheur already knew this was unlikely to happen).
France might supply an erecting shop, if convenient; in any case it might be wiser to build a new one (So a completely new factory would have to be built in France).
A joint supply of components. Britain would supply guns, ammunition and armour; the USA engines, transmissions, forgings and chains (employing US car industry).
The design would be based on British experience and American ideas and resources, and be superior in power, loading and trench crossing.
Major Alden would finish the working drawings before Christmas enjoying full cooperation of the British; the design was to be approved by both nations.
Unskilled labour would be provided by imported Chinese; the French government ensured their local accommodation.
Production would begin in April 1918 and finally reach 300 a month (So the number of 1500 was only preliminary).
The project would have high priority.
Management would be in the hands of two Commissioners, one British (Stern himself) and one American; but the French could appoint their own if their interests were concerned.

The plan already contained some specifications: the tank should have a 300 hp (220 kW) engine, weigh 38.8 tons and have a trench crossing capacity of 14 feet (4.3 m). Also the name of the tank was stated: the Liberty.

The first design conference took place on 4th December and Churchill approved the plan soon afterwards. It was made into a formal treaty signed by the British Foreign Secretary Arthur Balfour and the US Ambassador Walter H. Page on 19th January 1918. The treaty specified the programme in great detail. The first 1500 tanks had to be made by the end of the year and production should be expanded to 1200 a month. Both goals were very ambitious given the fact there was neither a completed design nor a factory and that British tank production would in fact be 150 a month during 1918.

The United States would supply: the engine; radiator; fan; piping; silencer; lighting; dynamo; battery; propeller shaft; transmission, including gearbox; brakes; roller sprockets; gear shift and brake control; track links and pins; rear track sprockets, hub and shafts; front idler hub and shafts; track roller, track spindles and bushings.

Britain would supply: bullet and bomb-proof plates; structural members; track shoes and rollers; guns, machine guns and mountings; ammunition racks and ammunition.

The agreed price was to be 5000 pounds per vehicle.

In December 1917 Stern had ordered to halt the Mark VI project ensuring that the Mark VIII would be the new standard Allied weapon: the International Tank.

[edit] Description

The Mark VIII kept many of the general features of the Mark I-V series: it had their typical high track run and no revolving turret but two sponsons, one on each side of the tank, armed with a 57 mm gun. But it also resembled the Mark VI-project in that it had more rounded and wider tracks and a large superstructure on top directly beneath the front of which the driver was seated. An innovative feature was the departure from the concept of the box tank with its single space into which all accessories were crammed. The Mark VIII was compartimentalised with a separate engine room at the back. This vastly improved fighting conditions as a bulkhead protected the crew against deafening engine noise, noxious fumes and heat.

There were no machine guns in the sponsons, only the 6-pounders each manned by a gunner and loader. The side machine guns were to the rear of the sponsons mounted in the hull doors. Major Alden had designed the sponsons to be retractable by the crew (they could swing in at the rear, being pivoted at the front), to reduce the width of the vehicle if enemy obstacles were encountered. Five more machine guns were in the superstructure: two at the front — left and right next to the driver — and one on each of the other sides. As there was no machine gun position covering the back of the tank there was a dead angle vulnerable to infantry attack. To solve this problem a triangular steel deflector plate was attached. The rear superstructure machine gunner could use it to deflect his fire down into that area behind the tank. The tank carried 208 shells and 13,848 machine gun rounds, mostly in a large ammunition locker in the centre which formed a platform on which the commander stood behind the driver observing the battlefield through a cupola with four vision slits.

The twelfth crew member was the mechanic, seated next to the 300 hp V-12 Liberty engine. Three armoured fuel tanks at the rear held 200 Imperial gallons (909 liters) of fuel giving a range of 89 km. The transmission used a planetary gearbox giving two speeds in either forward or reverse. Top speed was 5.25 mph (8 km/h).

To improve its trench crossing ability to 4.88 m the vehicle had a very elongated shape. The track length was 10.42 m but even though the hull width was an impressive nominal 3.76 m, the actual length-width ratio of the tracks was very poor as that width included the sponsons. Combined with wide tracks it proved difficult to turn the tank. During testing many tracks twisted and broke in a turn and it was decided to use longer, stronger 13.25 inch (337 mm) links made of hardened cast armour plate, stiffened by webs formed by recesses in the track plate. Another effect of the narrow hull was that the fighting compartment was also very narrow . This was made worse by the fact that now the gap between the double track frames at each side was very wide; earlier types had only the tracks themselves widened. Nevertheless the tank was supposed to accommodate another twenty infantry men in full gear if necessary. In absolute terms the vehicle was very large: 3.13 m tall the Mark VIII was the second largest operational tank in history, after the Char 2C. However its weight was only 37.6 metric tons as the armour plate was thin with a thickness of 16 mm — a slight improvement over the Mark V but very thin by later standards. The roof and bottom of the hull were protected by only 6 mm thick armour plate, so the tank was very vulnerable to mortar shells and mines.

[edit] Production

The French government hoped to receive 700 Mark VIII's for free, as the French superheavy tank, the Char 2C, could not be produced in sufficient numbers, if at all. However, suffering from a lack of manpower and raw materials the French were not forthcoming in providing any facilities for the production of the International Tank. Soon the Americans decided to build a brand new assembly factory at Neuvy-Pailloux, contracting a British company. Far from producing its first tank in April, the factory was not even finished by June. The Americans then tried to find a producer in the USA, but failed. In August they contracted another British firm. It finished the factory in November, by which point the war had already ended - not a single tank would be built there.

There were also serious delays in the production of the components. The Liberty engine was redesigned to replace expensive steel parts with cheaper pig iron. These redesigned engines were only produced in October. The British finished the prototype hull, made of unhardened steel, in July and sent it to the States. On arrival it transpired that no mass-produced parts were ready to finish the prototype, so the Locomobile Automobile Company in Bridgeport, Connecticut made these all by hand, completing the first vehicle on the 28th September. Testing began on 31 October. Only then was the armament shipped from Britain, two guns and ten Hotchkiss machine guns.

Testing was finished after the war and it was decided to build 100 vehicles in the USA; these were constructed in 1919 and 1920 by the Rock Island Arsenal for 35,000 dollars each, using British armour plates.

Meanwhile the British government had decided to start production in Britain. One thousand five hundred vehicles were ordered from the North British Locomotive Company, William Beardmore and Company and Metropolitan, using a 300 hp (220 kW) V12 Ricardo engine. Only the first managed to produce a prototype before the end of the war, testing it on the 11th November - the day of the Armistice. From parts already produced a further 24 vehicles were completed after the war. Five were sent to the training centre at Bovington, in Dorset - the others went straight to the scrap dealer.

[edit] Mark VIII*

During 1918, the then prevalent preoccupation with trench crossing capabilities led to preparations being made for the production of an even longer tank: the Mark VIII* (Star). The hull was to be lengthened a full three meters: four feet at the front and six feet at the back. This way it should be able to cross a trench 18 feet wide. To ensure that the tank could turn at all, despite its critically high length-width ratio, the bottom profile of the tracks would be more strongly curved, so that a smaller part of the track would touch the ground. Ground pressure would have increased however, as total weight reached 42.5 tons. If the tank had sunk into soft ground somewhat, it's questionable whether it would have been able to make a turn. No prototype was built.

[edit] Operational history

The American Liberty tanks equipped a single unit: the 67th Infantry (Tank) Regiment, based in Aberdeen, Maryland. The curious designation of the unit had its origin in the fact that since 1922 by law all tanks had to be part of the Infantry. The two machine gun positions at the sides of the superstructure were eliminated, so the crew could be reduced to ten. Water-cooled M1917 Browning machine guns were used. Despite many modifications the vehicles suffered from overheating and poor reliability, causing a prejudice in the Army against the use of heavy tanks. From 1932 onward they were phased out; all were in storage in 1934. In 1940 Canada had a lack of training tanks and bought most vehicles at scrap value.

A single Liberty tank survives at Fort Mead in Maryland.

The British never allocated their Mark VIII's to a tank unit; a single vehicle survives at the Bovington Tank Museum.