Mark I tank

The British Mark I was the first tank, entering service in World War I, born of the need to break the domination of trenches and machine guns over the battlefields of the Western Front in World War One. It and subsequent variations were the most successful heavy tanks of the war.

Description

The Mark I was a rhomboid-shaped vehicle with a low centre of gravity and long track length able to grip muddy ground and cross trenches. Sponsons (also called "barbettes") on the hull sides carried two Naval 6-pounder guns. There were two Hotchkiss machine guns in the sponsons and two removable guns for the front and back.

The hull was undivided internally; the crew shared the same space as the engine. The environment inside was extremely unpleasant; the atmosphere a mix of poisonous carbon monoxide, fuel and oil vapours from the engine and cordite fumes from the weapons. Temperatures inside could reach 50 °C. Entire crews lost consciousness or became violently sick when again exposed to fresh air. Ventilation was insufficient due to too low a flow rate of air in and out of the tank.

To counter the fumes inside and the danger of bullet splash or fragments and rivets knocked off the inside of the hull, the crew wore goggles and chainmail masks. Gas masks were standard issue as well, as they were to all soldiers at this point in the war (see Chemical warfare). The side armour of 8 mm initially made them largely immune to small arms fire, but could be penetrated by the recently developed armour-piercing K bullets. There was also the danger of being overrun by infantry and attacked with grenades. The next generation would have thicker armor to become nearly immune to the K bullets. In response the Germans developed a larger purpose-made anti-tank rifle, and also a Geballte Ladung (‘Bunched Charge’) - several regular stick grenades bundled together for a much bigger explosion.

A direct hit on the roof by an artillery or mortar shell could cause the fuel tanks, which were placed high in the front horns of the track frames (either side of the drivers' area) to allow gravity feed, to burst open. Incinerated crews would be removed by special teams that were forbidden to have any contact with the live ones.

Steering was difficult; controlled by varying the speed of the two tracks. Four of the crew, 2 drivers (one of which also acted as commander; he operated the brakes, the other the primary gearbox) and 2 'gearsmen' (one for the secondary gears of each track) were needed to control direction and speed - not that the Mark I was ever able to do more than a walking pace. As the noise inside was deafening, the driver, after setting the primary gear box, communicated with the gearsmen with hand signals, first getting their attention by hitting the engine block with a heavy spanner. For slight turns the driver could use the steering tail: an enormous contraption dragged behind the tank consisting of two large wheels, each of which could be blocked by pulling a steel cable causing the whole vehicle to slide in the same direction. If the engine stalled, the gearsmen would use the starting handle - a large crank between the engine and the gearbox.

There was no wireless; communication with command posts was by means of two pigeons, which had their own little exit hatch in the sponsons, or by runners who were encouraged to complete their suicidal mission by receiving bottles of strong liquor as reward.

Later Marks carried semaphore arms for signalling.

See history of the tank also for more on early tank development

Production History

The Mark I was a development of Little Willie, the experimental tank produced for the British Army by Lieutenant W. G. Wilson and William Tritton in 1915. Working on problems discovered with Willie, the Mark I was developed. Among these the fact that a gun turret above the hull would have put the centre of gravity too high, hence the guns were put in sponsons. The prototype Mark I was called "Mother". 150 were built. See history of the tank for a fuller story.

Variants

A requirement was found for two types of armament, so Mark I's were armed either with 6 pounder guns and four machine guns and called "Male" (75) or two Vickers machine guns instead of the 6 pounders and called "Female" (75).

To aid steering a pair of large wheels were added behind the tank. These were not as effective as hoped and subsequently dropped.

The subsequent Mark II, III, IV and V and later tanks all bear a strong resemblance to their 'Mother'.

Mark I

Crew: 8
Combat Weight
- Male: 28 tons (28.4 tonne)
- Female: 27 tons (27.4 tonne)
Armour: .23-.47 in (6-12 mm)
Armament
- Male: two 6-pounder QF, four 8 mm Hotchkiss Machine Guns
- Female: four .303 Vickers Machine Guns, two 8 mm Hotchkiss Machine Guns

The Gun Carrier Mark I was largely produced with parts identical to those used to build the Mark I.

Mark II

Unhardened armour. Built from December 1916 for training only, but used in the Battle of Arras in April 1917 because of delays in the production of the Mark IV. 50 built. Five Mark II's were used to test transmission types for the new Mark IV.

Mark III

Training tank. Used Lewis machine guns. Smaller sponson for the Females. 50 built. It was originally intended that the Mark III have all the proposed new design features of the Mark IV. This is why there were two distinct training types, the Mark II being little more than a slightly improved Mark I. Development of the new features was so slow however, that the change from the Mark II was very gradual only. The last two Mark III's were melted down in WWII.

Mark IV

An up-armoured version of the Mark I with all fuel stored in a single external tank (located between the rear track horns) in an attempt to improve crew safety. The sponsons could be pushed in to reduce the width of the tank for rail transportation. Rails on the roof carried an unditching beam. 1220 built: 420 Males, 595 Females and 205 Tank Tenders which were supply tanks.

The director of the Tank Supply Department, Albert Gerald Stern, first intended to fit the Mark IV with a new engine and transmission. Production of battle tanks was halted until the new design was ready, necessitating the Mark II and III as interim training tanks. He failed however to complete development soon enough to start production in time to have 200 tanks ready for the promised date of 1 April 1917. He was ultimately forced to take a Mark IV in production in May 1917 that was only slightly different from the Mark I.

The Mark IV Male carried 4 Lewis machine guns as well as the two sponson guns (now with shorter barrels). The Female had six machine guns. Two of the machine guns were operated by the gun loaders.

Specs
Crew: 8
Combat Weight
Male: 28 tons (28.4 tonnes), Female: 27 tons (27.4 tonnes)
Armour: .25-.47 in (6.1 - 12 mm)
Armament
- Two 6-pounders & Four .303 Lewis MG (Male), Six .303 Lewis MG (Female)
Ammo storage
- 6 pounder: 180 HE rounds and remainder Case

Mark V Series

=Mark V

The Mark V was first to be a completely new design. When however in December 1917 the desired new engine and transmission came at last available, this design was abandoned and the designation switched to an improved version of the Mark IV, in fact a Mark IV as it was originally intended: more power (150 bhp) with a new Ricardo engine, improved steering mechanism and epicyclical transmission, only one driver was needed. Cabin for machine-gunner on the roof. 400 were built, 200 each of Males and Females. Several were converted to Hermaphrodites by swapping sponsons to give a single 6 pounder gun for each.

=Mark V*

Sir William Tritton in 1917 developed the Tadpole Tail: an extension of the tracks to be fitted to the back of a tank to improve trench crossing abilities. This was necessary because the Hindenburg Line had 3.5 meter wide trenches to stop the British tanks. When Major Philip Johnson of Central Tank Corps Workshops heard of this project, he immediately understood that the weight of the heavy girders strengthening the attachment might be put to a better use by creating a larger tank. He cut a Mark IV in half and stretched the hull, lengthening it by six feet. When details had been forgotten it has for a long time been assumed that most Mark V* had been field conversions made by Johnson. We now know that they were all factory-built. It had a larger 'turret' on the roof and doors in the side of the hull. The weight was 33 tons. 645 were built out of an order for 500 Males and 200 Females.

The extra section was also designed to house a squad of infantry. This was the first ever purpose designed tracked APC, it was also the first APC to be significantly armed, as some earlier conversions of tanks to supply carriers lack any armament. It also functioned as a main battle tank, and it would not be till the Merkava that again a APC was made that was also a MBT capable of front-line combat.

=Mark V**

Because the Mark V* had been lengthened, its original length-width ratio had been spoiled. Lateral forces in a turn now became unacceptably high causing thrown tracks and an enormous turn circle. Therefore Major Wilson in May 1918 redesigned the track, with a stronger curve reducing ground contact (but increasing ground pressure as a trade-off). An uprated 225 hp Ricardo engine was fitted. The cabin for the driver was combined with the roof cabin; there now was a separate machine gun position in the back. 197 were built out of an order for 750 Males and 150 Females.

=Mark V***

= See: Mark X.

Mark VI

The Mark VI was a project with a gun in the front of a completely redesigned hull without sponsons. It did not progress past the stage of a wooden mock-up.

Mark VII

One of the Mark II's used as test vehicles had had a hydraulic transmission. In October 1917 Brown Brothers in Edinburgh were granted a contract to further develop this line of research. In July 1918 the prototype was ready. Its drive system was very complex. The Ricardo engine drove into Variable Speed Gear pumps that in turn powered two (Williams-Janney)hydraulic motors, moving one track each by means of several chains. To ward off the obvious danger of overheating there were many fans, louvres and radiators. Steering was easy and gradual however and the version was taken into production to equip one tank battalion. Three were built out of an order for 74 when war ended. The hull was slightly lengthened in comparison with the Mark V. No Mark VII's survive.

Mark VIII

American involvement in the development of the tank design led to the Mark VIII, also known as 'Liberty' or Anglo-American tank (though initially the French were partially involved).

The engine was compartmentalised from the crew, and the turret structure included forward and rear firing machine guns. Of a planned (shared production) 1500 each, 24 were built by the British before they pulled out of the project and 100 completed by the Americans. The 100 were produced between September 1918 - 1920, at the Rock Island Arsenal at a cost of $35,000 apiece.

They were used and upgraded up until the 1930s when given to Canada for training (as opposed to the M1917's which were sold at scrap value). The tank itself was over 34 feet long, and there had been an even longer 44 foot version planned but never made (the Mark VIII*). The tank was outdated by the 1930s due to its speed (under 6 mph) and armour (16 - 6 mm) but it did have one of the longest independent trench crossing capabilities of any AFV ever made. Modern MBT's and AFV's rely on bridge laying tanks for crossing large deep trenches.

Crew: 12 (later 10)
Weight 37 tons to 40 tons
Length/Height/Width : 34.16'/10.25'/12.33' (Mark VIII* length 44')
Engine: Ricardo 300 hp gasoline (UK), Liberty V12 340 hp (US)

Mark IX

The Mark IX was a troop carrier or infantry supply vehicle - among the first tracked Armoured personnel carrier not counting experiments with the lengthened Mk V's. 34 were built out of an order for 200. The last surviving exemplar can be seen at Bovington Tank Museum, Dorset.

Mark X

Paper only project to improve the Mark V, originally known as Mark V***. This was basically a contingency plan in case the Mark VIII project would fail (if so a production of 2000 was foreseen for 1919), trying to produce a tank with as many parts of the Mark V as possible but with improved manoeuvrability and crew comfort.

Combat History

The first tanks were added, as 'Heavy Branch', to the Machine Gun Corps until a separate Tank Corps was formed on 28 July 1917 by Royal Warrant.
A small number of Mark I tanks took part in the battle of the Somme during the Battle of Flers-Courcelette in September 1916. Although many broke down or became stuck, almost a third that attacked made it across no mans land, and their effect on the enemy was noted leading to a request by the British C-in-C Douglas Haig for a thousand more. This came as a bit of a surprise: William Tritton had already started the development of a heavier tank: the Flying Elephant. Unfortunately it also gave the Germans time to develop a specifically designed anti-tank weapon for the infantry, an armour piercing 7.92 bullet.
Mark IV tanks were used at the Third Battle of Ypres (Passchendaele) in Mid 1917, but without great success due to the mud.
Nearly 460 Mark IV tanks were used during the Battle of Cambrai in November 1917, showing that a large concentration of tanks could quickly overcome even the most sophisticated trench system.
During the Battle of Amiens in August 1918 Mark V tanks with the new Whippet tank penetrated the German lines in a foretaste of modern armoured warfare.
The first tank to tank battle was between Mk IV tanks and German A7Vs (see that entry for details).

External links

http://www.spartacus.schoolnet.co.uk/FWWmother.htm
http://www.tankmuseum.co.uk/colww1.html

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