British heavy tanks were a series of related armoured fighting vehicles developed by the UK during the First World War.

The Mark I was the world's first tank, tracked and armed armoured vehicle, to enter combat. The name "tank" was initially a code name to maintain secrecy and disguise its true purpose.[3] The type was developed in 1915 to break the stalemate of trench warfare. It could survive the machine gun and small-arms fire in "No Man's Land", travel over difficult terrain, crush barbed wire, and cross trenches to assault fortified enemy positions with powerful armament. Tanks also carried supplies and troops.

British heavy tanks are distinguished by an unusual rhomboidal shape with a high climbing face of the track, designed to cross the wide and deep trenches prevalent on the battlefields of the Western Front. Due to the height necessary for this shape, an armed turret would have made the vehicle too tall and unstable. Instead, the main armament was arranged in sponsons at the side of the vehicle. The prototype, named "Mother", mounted a 6-pounder (57 mm) cannon and a Hotchkiss machine gun at each side. Later, subtypes were produced with machine guns only, which were designated "Female", while the original version with the protruding 6-pounder was called "Male".

The Mark I entered service in August 1916, and was first used in action on the morning of 15 September 1916 during the Battle of Flers-Courcelette, part of the Somme Offensive.[4] With the exception of the few interim Mark II and Mark III tanks, it was followed by the largely similar Mark IV, which first saw combat in June 1917. The Mark IV was used en masse, about 460 tanks, at the Battle of Cambrai in November 1917. The Mark V, with a much improved transmission, entered service in mid-1918. More than two thousand British heavy tanks were produced. Manufacture was discontinued at the end of the war.

The Mark I was a development of Little Willie, the experimental tank built for the Landships Committee by Lieutenant Walter Wilson and William Tritton between July and September 1915. It was designed by Wilson in response to problems with tracks and trench-crossing ability discovered during the development of Little Willie. A gun turret above the hull would have made the centre of gravity too high when climbing a German trench parapet (which were typically four feet high),[5] so the tracks were arranged in a rhomboidal form around the hull and the guns were put in sponsons on the sides of the tank. The reworked design was also able to meet the Army requirement to be able to cross an 8 ft (2.4 m) wide trench.

A mockup of Wilson's idea was shown to the Landships Committee when they viewed the demonstration of Little Willie. At about this time, the Army's General Staff was persuaded to become involved and supplied representatives to the Committee. Through these contacts Army requirements for armour and armament made their way into the design. The prototype Mark I, ready in December 1915, was called "Mother" (previous names having been "The Wilson Machine", "Big Willie", and "His Majesty's Land Ship Centipede"). Mother was successfully demonstrated to the Landships Committee in early 1916; it was run around a course simulating the front including trenches, parapets, craters and barbed wire obstacles. The demonstration was repeated on 2 February before the cabinet ministers and senior members of the Army. Kitchener, the Secretary of State for War, was skeptical but the rest were impressed. Lloyd George, at the time Minister of Munitions, arranged for his Ministry to be responsible for tank production.[6]

The Landships Committee was re-constituted as the "Tank Supply Committee" under the chairmanship of Albert Stern; Ernest Swinton, who had promoted the idea of the tank from the Army angle was also a member. General Haig sent a staff officer Hugh Elles to act as his liaison to the Supply Committee. Swinton would become the head of the new arm, and Elles the commander of the tanks in France.[6]

The first order for tanks was placed on 12 February 1916, and a second on 21 April. Fosters built 37 (all "male"), and Metropolitan Carriage, Wagon, and Finance Company, of Birmingham, 113 (38 "male" and 75 "female"), a total of 150.[7]

When the news of the first use of the tanks emerged, Lloyd George commented,

"Well, we must not expect too much from them but so far they have done very well, and don't you think that they reflect some credit on those responsible for them? It is really to Mr Winston Churchill that the credit is due more than to anyone else. He took up with enthusiasm the idea of making them a long time ago, and he met with many difficulties. He converted me, and at the Ministry of Munitions he went ahead and made them. The admiralty experts were invaluable, and gave the greatest possible assistance. They are, of course, experts in the matter of armour plating. Major Stern, a business man at the Ministry of Munitions had charge of the work of getting them built, and he did the task very well. Col Swinton and others also did valuable work."
— David Lloyd George[8]

Description

The Mark I was a rhomboid vehicle with a low centre of gravity and long track length, able to negotiate broken ground and cross trenches. The main armament was carried in sponsons on the hull sides.

The hull was undivided internally; the crew shared the same space as the engine. The environment inside was extremely unpleasant; since ventilation was inadequate, the atmosphere was contaminated with poisonous carbon monoxide, fuel and oil vapours from the engine, and cordite fumes from the weapons. Temperatures inside could reach 50 °C (122 °F). Entire crews lost consciousness inside the tank or, sometimes, collapsed when again exposed to fresh air.[9]

To counter the danger of bullet splash or fragments knocked off the inside of the hull, crews were issued with leather-and-chainmail masks.[10] A leather helmet[11] was also issued, to protect the head against projections inside the tank. 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 had thicker armour, making them nearly immune to the K bullets. In response, the Germans developed the 13.2 mm Mauser anti-tank rifle, and also a Geballte Ladung ("Bunched Charge") – several stick grenades bundled together for a much bigger explosion.

A direct hit 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 were removed by special Salvage Companies, who also salvaged damaged tanks.

Steering was difficult, controlled by varying the speed of the two tracks. Four of the crew, two drivers (one of whom also acted as commander; he operated the brakes, the other the primary gearbox) and two "gearsmen" (one for the secondary gears of each track) were needed to control direction and speed, the latter never 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. Many of these vehicles broke down in the heat of battle making them an easy target for German gunners. There was no wireless (radio); communication with command posts was by means of two pigeons, which had their own small exit hatch in the sponsons, or by runners. Because of the noise and vibration, early experiments had shown that radios were impractical, therefore lamps, flags, semaphore, coloured discs, and the carrier pigeons were part of the standard equipment of the various marks.[12]

During the First World War, British propaganda made frequent use of tanks, portraying them as a wonder weapon that would quickly win the war. They were featured in films and popular songs.