Big Willie/ Mother

Big Willie or Mother was the second British tank prototype, and became the basis of the Mark I Tank, the Mark II and Mark III training tanks and the Mark IV Tank.

The first British tank to be completed, Little Willie, had been designed and built at  Foster’s Engineering Works of Lincoln, and designed by their head engineer William Tritton, and Major W.G. Wilson, a pre-war automobile engineer. As first built the vehicle used Bullock Commercial tracks, carried low on the sides of the boxy fuselage. In its original configuration it carried a dummy turret, and the aim was to give it a 2-pounder gun in a rotating turret.

Although Little Willie and Mother are normally presented as a sequence, they were actually developed alongside each other. Work on building Little Willie (then known as the No.1 Lincoln Machine) began on 11-12 August 1915, and on 17 August 1915 Walter Wilson first suggested the layout of Mother, with tracks running all the way around the body of the vehicle. Work on this second design was approved in the following week.

The new machine kept the same rectangular box like hull shape as Little Willie, but it was now carried between big track frames that brought the track over the top of the vehicle. This allowed the front of the tracks to be raised high above the ground, to improve its ability to climb vertical parapets. The vehicle was also longer than Little Willie, allowing it to cross the 5ft wide trenches required by the War Office.

The tracks themselves had been designed by Tritton, after a series of attempts to replace the Bullock tracks originally used on Little Willie had failed. His new system used a pair of steel chains which had 20.5in wide steel plates riveted to them. The feet had a supporting lip at one end to keep them in place (and close the gaps between them thus reducing the potential for muck to get into the mechanism). The track was carried on a series of small road wheels along the bottom and ran along guide rails on the top. Both the rear drive and front idler wheels had teeth on Mother and the Mark I, but a smooth idler wheel was soon introduced. The lower part of the track was gently curved, so that on hard ground only eight of the ninety track links on each side touched the ground, making it easier to steer. On softer ground more of the track came into contact, reducing ground pressure but making it harder to steer.

Mother was powered by 105hp Daimler engine that was placed right in the middle of the crew compartment. Power went to the main gearbox then to the massive differential which filled up the rear of the tank. Power from the differential went sideways to secondary two speed gear boxes installed in the track frames, just behind the sponsons. Roller chains connected these gear boxes to the rear drive wheels. The original purpose of these extra gear boxes was to give a wider range of gears for the heavier tanks, but they also proved to be useful for steering.

The early tanks were very difficult to steer. There were four different ways to steer the vehicle, each with their own disadvantages. The first was to use the tail wheels, but although this had originally been see as the main way to turn sharply, they soon proved to be ineffective.

The second, used to ‘steer slightly’, was for the commander to engage the brakes on the side he wanted to turn towards, so that that track would move slower. This was hard work as the brakes were entirely manual, and also quickly wore the brakes down.

The third method, used to turn on the spot, involved stopping the tank and locking the differential (thus linking the two drive wheels). The secondary gears on the direction you wanted to turn would be put into neutral and the brake applied to that track. The other secondary gear and the primary gear box would be put into first gear. Power would be applied, and the one moving track would turn the tank on the spot. The tank then had to be stopped to reengage the gears and unlock the differential.

The fourth method was to leave the differential unlocked, put the secondary gear box on the side you wanted to turn towards into high ratio (low gear by modern car standards) and low ratio (high gear) on the other side, so the inner track would run slower than the outer track. In theory this would allow the tank to carry out a fairly sharp turn without stopping, but it was considered to be bad for the secondary gear shafts.

The new design meant that the armament had to be modified. The original plan for Little Willie had been to carry a gun in a rotating turret on top of the vehicle, but Mother was taller than Little Willie, and a turret would have dangerously raised the centre of gravity, making the tanks rather unstable. The turret would also have been directly above the engine. The director of Naval Construction, Eustace Tennyson d’Eyncourt, who was a member of the Landship Committee, suggesting fitting guns in sponsons carried on the sides of the tank. This was similar to the system used on many warships of the period, and there was plenty of space between the upper and lower parts of the track frames.

The next question was what gun to use. The pressures of the war meant that suitable guns were rare. Eventually the Admiralty suggested using a Naval Six Pounder, which was a quick firing gun that had been produced in 1915 by modifying a Hotchkiss 57mm gun that had been in naval service since 1885. 

The 6-pounder was mounted on a pedestal inside the sponson. A large gap was left in the structure of the sponson to give the gun a 100 degree arc of fire.  A curved shield was fitted to the gun, and rotated with it to block the gap. In order to provide complete protection this shield ran around a 200 degree arc. There was a small vertical slit in the shield which carried a telescope sight mounted to the gun. Each gun needed a gunner and loader, with the loader on the right and gunner on the left. As a result the two sides had different arcs of fire – dead ahead to 110 degrees on the starboard (right) side, 5 degrees to 115 degrees on the port (left) side - to make sure there was room for the loader on both sides.

A full size wooden mock-up was sent to the Wembley experimental ground where it was inspected by the War Office, Ministry of Munitions, Landship Committee members and others on 29 September (only a week after Little Willie’s first public trials).

Construction of ‘Mother’ began on 28 October. In an attempt to keep the work secret the hull was designated as a ‘Water Carrier for Mesopotamia’, or a water tank. The first of the new Tritton tracks was bench tested on 22 November, and installed on Little Willie on 3 December. They were tested at Burton Park on 8 December and performed well. Mother moved under her own power for the first time on 7 January 1916. On 12 January she climbed over piles of scrap and pig iron in the yard without problems. On 13 January she left the yard and was driven to Poppleton’s Field, taking a cross country route to test her abilities. Once again she performed well. The first live firing exercises took place on 20 January and she proved to be a stable gun platform. She also crossed the required 5ft wide trench.

The name ‘Tank’ was first used in official documents on 24 December, after it was decided to stop calling them Landships in an attempt to keep the secret.

At the end of January 1916 Mother and Little Willie were taken by train down to Hatfield House, for her first official demonstration. A course resembling British and German trenches and no-mans land was built, with replica shell holes and a swamp.  A first test run was carried out on 29 January in front of Admiral Tudor, General Scott-Moncrieff and others, and was a success. The official trial was held on 2 February in front of an audience that included an unexpected appearance by Lord Kitchener. Kitchener appeared not to have been impressed on the day, describing it to Tritton as a ‘Pretty mechanical toy, but without serious military value’, and saying that it would be knocked out by artillery. However after the war Gen Whigham, who had been with Kitchener on the day, claimed that he had actually been very impressed with the tank, but worried by the lack of secrecy implied by the public trials, and had left early to convince anyone watching he wasn’t interested. However he had spent most of the morning questioning Tritton, and on the following day told the War Committed that he had been impressed by the trials. General Haig’s representatives were clearly more impressed, and asked when they could have some tanks

Haig’s initial response was to ask for 30-40 machines, but on 12 February an order for 100 machines was placed. These would be built as the Mark I Tank, with 24 to be built by Foster’s and 75 by Metropolitan in Birmingham. Daimler would build the engines, Beardmore, Cammell Laird and Vickers the armour. The first tanks would see their combat debut later in the year on the Somme, but didn’t really come into their own until late in 1917 at Cambrai and during the fighting of 1918. However ‘Mother’ was the basis of all that was to come, at least on the British side.

Wilson Machine, Centipede, Big Willie, Mother

Production: 1
Hull Length: 32.5ft
Hull Width: 13.75ft (including Sponsons)
Height: 8ft
Crew: 8
Weight: 28 tons
Engine: 105hp Daimler-Foster gasoline engine
Max Speed: 3.7mph
Armament: Two 6-pounder guns and four machine guns
Armour: Mild steel

Books on the First World War | Subject Index: First World War

How to cite this article: Rickard, J (20 June 2023), Big Willie/ Mother ,

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