Weight 28 tons
Length, width and height 9.9m, 4.2m, 2.4m
Fuel capacity 227.3 litres
Max speed 5.9km/h
Fuel consumption 5.9 litres/km
Armament Two six-pounder (57mm) quick-firing and four 7.62mm Hotchkiss air-cooled machine guns
Birth of the tank
It was a British invention, but the idea behind the tank was old: to effectively combine 'firepower, protection and mobility'. In February 1915, First Lord of the Admiralty Winston Churchill created the 'Landships Committee' to investigate a mechanical solution to the stalemate of trench warfare. The first successful tank prototype, known as 'Mother', completed secret trials in early 1916. The new 'Mark I' tank was used in battle for the first time at Flers-Courcelette on 15 September 1916. Ninety years later, the tank has altered beyond all recognition, but the basic principles of firepower, protection and mobility remain unchanged.
There were two types of Mark I tank: 'male' and 'female'. Male tanks mounted a six-pounder gun in each sponson, plus three light machine guns. Female tanks had two heavy Vickers machine guns in place of the six-pounders.
The Hotchkiss six-pounder was an adapted naval gun with a range of 6,860 metres. It was served by a gunner and loader, neither of whom could stand or sit comfortably in the cramped interior. The gunner aimed using a simple telescopic sight, but the vibration of the tank was so severe that careful aiming was impossible unless the tank was completely stationary. Each male tank carried 334 shells, stowed in special tubes arranged around the interior of the tank.
The machine guns, also Hotchkiss, were for close defence if the tank was attacked by enemy infantry. One was located in each sponson, with a third at the front, firing through a loophole between the driver's and commander's visors. These guns tended to be temperamental due to the heat and vibration inside the tank.
The Mark I was powered by a large Daimler (of Coventry) six-cylinder engine with a 13 litre capacity, but it only produced a relatively puny 105 brake horsepower. Chosen for its smooth, quiet running, the engine was nonetheless located in the same compartment of the tank as the crew, where the heat, noise and exhaust fumes were almost unbearable.
The engine was started by four members of the crew winding a large crank handle. The engine was water-cooled, with the large radiator situated at the back of the tank. This was served by a heavy duty fan, which drew air from inside the tank and may have slightly alleviated the dreadful conditions inside.
Petrol was on a 'gravity feed' to the carburettor. This meant the two internal 25 gallon (113.5 litre) containers had to be situated high up, on either side of the front cab. If a tank became stuck in a nose-down attitude, the tank would stall, making it necessary to feed petrol to the engine manually.
A far greater danger was fire. If a tank was struck by a shell that ignited the fuel, the crew had little or no chance of escape. Additionally, the average range of a tank on its internal fuel supply was only 20-25 miles, depending on terrain, so crews carried as many extra petrol cans as possible on the roof of the tank where they were extremely vulnerable to damage. Petrol leaking into the tank from the roof could force the crew to evacuate.
Caterpillar tracks were key to the success of British tanks in World War One. When it was realised that commercially-available tracks were simply not up to the job, Albert Tritton of Foster & Co, Lincoln, came up with a new design. This enabled the adoption of the characteristic all-round track layout which gave British tanks their unrivalled cross-country performance.
Simplicity and strength were the key factors, but there were drawbacks. Small diameter rollers, located along the lower frames, were unsprung, so tanks bumped hard across rough ground, adding further to the discomfort of the crew.
A broken, or 'thrown', track could disable a tank at once, and replacing it was hard work. To prevent this, adjustable idler wheels at the front were used to keep the tracks taut, and track links were flanged so that they would not fall away from the rollers when the tank crossed a trench.
The Mark I had a crew of eight men, four of whom were required just to drive it. The process was complicated. The driver had control of a clutch, footbrake, hand throttle and primary gearbox, which gave two speeds forward and one in reverse. The commander, sitting to the driver's left, operated the brakes. At the back of the tank, two 'gearsmen' worked secondary, two-speed gearboxes located within the track frames.
For any major change in direction (known to tank men as 'swinging'), the driver stopped the tank and put the primary box in neutral. Depending on the direction of turn, the gearsmen selected a gear on one side and neutral on the other, while the commander held the brake. The driver then put the primary box in gear and the driven track 'swung' the tank around. The tank then had to stop again while the gears were reset.
The steering tail device worked on a principle similar to that of a boat's rudder and gave the tank a laborious 18 metre (diameter) turning circle. It was widely regarded by crews as a nuisance and was removed a few months after the Mark I was introduced.
In order to limit the weight of the Mark I to a 'manageable' 28 tonnes, the thickness of its armour plate was limited. In vital areas, such as the front, it was 10 mm thick. Elsewhere it was a minimal 6 mm. In theory, the crew were reasonably safe from small arms fire and shrapnel. Anything heavier would smash straight through the plate and probably wreck the tank.
The art of manufacturing thin armour was still in its infancy so the quality varied. Bullets were known to pierce the armour, particularly on the sponsons. Even if bullets failed to penetrate, the crew suffered a great deal from 'splash' - molten lead from the core of spent bullets that found its way through gaps in the armour to burn exposed skin and damage eyes.
The sponsons on 'male' tanks were naval in origin and were adopted in place of a rotating turret. A turret would have raised the centre of gravity to an unacceptable height, and being directly above the engine might well have roasted the crew.
The sponsons also had their flaws: they added weight, made it difficult for the driver to judge the width; would often become wedged in soft ground; and had to be removed and refitted when the tank was transported by train.
The male sponson included a pedestal for the gun and a curved shield of armour plate that rotated with the gun as the gunner swung it round, ensuring that the aperture was adequately covered at all times. The doors of the tank were located to the rear of each sponson.
In addition to the fumes, the cramped conditions and the deafening noise, it was virtually pitch black inside the Mark I when going into action. Every door, flap and hatch was shut tight against bullets, shrapnel and bullet 'splash' yet the crew had to be able to see outside both to drive and fight.
At the front, the commander and his driver had large flaps that could be opened in layered stages as required, and slim periscopes which poked up through holes in the cab roof. Elsewhere in the tank were narrow vision slits with crude periscopes which used shatterproof strips of shiny steel rather than glass blocks.
German troops soon learned to fire at the tank's vision devices, which the crews tried to camouflage with paint. Other apertures, covered by teardrop-shaped flaps, were designed not for vision but to allow crew members to use their revolvers.
If conditions inside the Mark I were appalling - deafening noise, roasting heat, suffocating fumes from the engine and the choking smell of cordite when in action - the men learned to live with it and still function as a team. Given that they were often in extreme danger and working in near-total darkness, their commitment was remarkable. Although the tanks were originally regarded as expendable, their crews took much pride in them, christening each one with an individual name, and repairing and recovering them after an action where possible. The Mark I crew comprised eight men.
Commander (front left) In 1916, he would have been a young officer. Besides the usual duties of command - determining the route, watching out for targets and the care of the crew - he was responsible for working a pair of steering brakes in conjunction with the driver. If the ground was bad or the route uncertain, the commander would often get out of the tank and walk ahead, testing the ground with a stick - holding a lit cigarette behind his back if it was dark - at the risk of enemy fire and being run down by his own tank.
The Driver (front right) The driver was regarded as the most skilled and valuable member of the crew. He was responsible for navigating the tank, gear changing, operating the throttle, applying the foot brake and operating the steering tail device by means of a steering wheel. He also supervised maintenance of the engine, clutch, gears and tracks.
Secondary Gearsmen (at the rear of the tank) The gearsmen were stationed on each side of the tank. They operated the secondary gearboxes relating to the individual tracks. They also passed forward ammunition, greased the tracks and operated the light machine guns.
Gunners and Loaders
In a 'male' tank, each six-pounder gun was served by a gunner and a loader. The gun was moved by the sheer physical exertion of the gunner, using a shaft under his right armpit to elevate and swing the weapon. He aimed using a telescopic sight and operated the firing mechanism manually.
The first tank crews came from virtually every regiment in the British Army. Consequently, there was little conformity in cap badges or uniform early on, but eventually they were made a branch of the Machine Gun Corps. This became the Tank Corps in July 1917, the Royal Tank Corps in October 1923 and the Royal Tank Regiment in April 1939.
Published: June 2006