The war that was widely expected to end by Christmas 1914 soon reached a stalemate, with thousands of men dying daily along 450 miles of fortified trenches running from the North Sea coast of Belgium through France to its border with Switzerland.
The opportunity for either side to break through the opposing lines had been all but lost, and it was recognised that whichever side was first to succeed in finding a practical way to breach the wire and cross the trenches would have a chance to break the deadlock, and might even win the war.
As early as 1915 David Lloyd George, then Minister of Munitions, had already perceived how the outcome of the war would be decided, when he said, "This is an engineers' war".
When confronted with images of the horrors of the Western Front it was inevitable that inventive minds would begin to consider alternatives, and in England a small group of men began to have the germ of a remarkable idea.
It was an idea that would lead to a small agricultural engineering company in Lincoln creating what might be considered one of the most important fighting machines ever invented.
William Rigby was a gifted draughtsman with a keen grasp of engineering principles and a knack of being able to push the available technology to its limits.
He was educated in Lincoln, and in 1904 he began work at Fosters, quickly rising through the company until he had progressed from being a lowly drawing office apprentice to becoming the company’s chief draughtsman.
His talent was to be able to produce highly-detailed engineering drawings in an extremely short time, and he was directly responsible for creating the drawings from which the first tanks were built.
He continued to work at Fosters until 1963, and gave many lectures on tank production and other subjects until his death, in January 1982.
Born in 1874, Walter Wilson was educated as a naval cadet at Dartmouth before moving on to King's College, Cambridge. He left with a first class honours degree, and a fertile mind full of ideas.
He designed and built his own cars, completely redesigned the sailing boat, and even dabbled in early aircraft design. All the machines he worked on were technologically advanced and of the highest quality. In 1906 he designed a combined armoured car and gun tractor for Armstrong Whitworth, but it was too advanced for its time, and no orders were placed for it.
He was a freelance engineer from 1908 until the outbreak of war, when he joined the Royal Navy's newly-formed Armoured Car Service. This led eventually to his involvement with the Admiralty's Landships Committee. In 1915 he was seconded to the William Foster factory in Lincoln to work alongside William Tritton and oversee developments on behalf of the Committee.
Tritton's experience, tenacious character and technical knowledge, combined with Wilson's design and engineering genius, made them a formidable team. Tracklaying technology was still very much in its infancy in 1915 but tracklaying vehicles were nevertheless eventually seen as the only viable option. By this time several different concepts were vying for the chance to break the deadlock in the trenches. These ideas were vetted by the newly-formed Admiralty Landships Committee, headed by the First Lord of the Admiralty, Winston Churchill.
One of the projects was ’Hetherington’s Big Wheel’, which had been designed by Major Thomas Hetherington. It was a huge machine, some 48 feet high, 80 feet long and weighing over 300 tons. The Foster factory was contracted to build the prototype. Its 40-foot wheels should have made crushing barbed wire and crossing trenches easy, but its huge size and weight would have made it quite impractible even to transport to the Western Front, apart from the fact that it would be unable to negotiate the deep mud of the battlefield.
Tritton and Rigby could nevertheless see the potential of the idea, and adapted it to something smaller and lighter, calling their design the 'Tritton Trench Crosser’. The new, smaller and more compact design would be powered by a 105hp Daimler engine of the type used in Fosters' heavy agricultural haulage tractors. However, as the wooden trial design took shape in the factory yard, it soon became apparent that the new concept would be too expensive to produce, and far too vulnerable to enemy fire, and it was decided to take the project no further.
Tritton was still enthusiastic about the basic principle of using tractors with large wheels rather than tracks, and in fact Fosters did produce a fully-working wheeled machine, the Tritton Trench Crosser, before building the true forerunner of the tank – the Number 1 Lincoln Machine.
The Tritton Trench Crosser
From the rear this machine looked like a standard Daimler Foster 105hp tractor. The view from the front was rather different.
The front wheels of the machine had been arranged to run in tandem, wooden extensions had been added to either side of the chassis, and the driver's position had been moved from the rear of the machine to a new position, just in front of the box radiator. Two narrow but sturdy long bridge sections were stowed along the sides, and a heavyweight winching chain had been added. Wood was used for the chassis extensions, so as to move the centre of gravity back towards the heavier rear end. Together with the tandem front end, this meant that, when the tractor was driven straight at a trench, the front wheels would easily span the gap while the rear end was still on the other side. The bridge sections would then be deployed by hand, and the rear wheels of the tractor would follow the nose over the trench. Once the machine was safely over the trench, the bridge sections would be winched back into place.
But although it could certainly cross trenches, albeit slowly, it could neither operate on rough ground nor deal with barbed wire. It became clear that any future designs would have to run on tracks.
The Number 1 Lincoln Machine
Some years earlier, Fosters had collaborated with Ruston and Hornsby, of Grantham, to produce the Yukon Tractor, which had used Hornsby chain tracks instead of wheels. Fosters later produced a halftrack machine called the Centipede, and this was a major reason why the Landships Committee turned to Fosters in 1915 in the quest to develop a tracklaying trench crossing machine.
In August 1915 Walter Wilson proposed that it would be more beneficial to have the tracks travel right round the machine, producing what was, in effect, a very large wheel on either side. A week later Tritton was back in London for an interview with the Director of Naval Construction, Tennyson D’Eyncourt, with their proposal for the new rhomboid design. It was immediately approved.
Work commenced without delay, and the assembled machine was subjected to trial runs on Lincoln’s South Common. However, the tracks used, of the American 'Bullock' type, proved completely unsuitable, as Wilson had foreseen. The fact was that, at that time, there were no suitable tracks being produced anywhere in the world.
To enable them to work without distractions on what seemed to be an almost insurmountable problem, Wilson and Tritton set up a temporary drawing office at the White Hart Hotel in uphill Lincoln. There they worked for hours and days on end to solve the problem. Drawings of unworkable ideas were burnt in the fireplace of the Yarborough Suite, and more promising ideas sent downhill to the factory for testing, but nothing seemed to work.
At last Tritton managed to work out the problem, by creating a simple chain link of pressed steel plates riveted along its whole length.
On 22 September 1915 he sent his famous telegram to the Admiralty:-
"New arrival by tritton out of pressed plate STOP
Light in weight but very strong STOP
All doing well thank you STOP
The idea for Little Willie had been born.
Tritton had gone back to engineering basics, and had come up with his new idea for the tracks. They would be unsprung, and thus simple and hard-wearing. There seemed to be no practical reason why they could not merely be lengthened to travel around the entire machine on future designs. The Number 1 Lincoln machine was given the new tracks and renamed 'Little Willie'.
To all intents and purposes Little Willie seemed to be little more than a box on tracks but, in technical terms, the model was ideal for open ground and for crossing trenches. However, it could not span trenches quite as wide as those specified by the military, or the even wider trenches now being contructed by the enemy.
The drive from the engine, which was located at the rear, passed though a cone clutch, incorporated within the flywheel, into a two-speed-and-reverse gearbox, and from there into a massive differential casing. It then passed, via a series of sprockets and chains, to the track drive sprockets at the rear. Ahead of the differential was a narrow shelf with seats, which accommodated the driver, sitting on the right, with another crew member on his left, who operated the steering levers. These could slow down one track or the other, as required, to assist in changing direction. Very little thought was given to the comfort of the crew, which was clearly not a priority at the time.
Tritton suggested that it should also be steered by a pair of wagon-type wheels extending from the rear, to act rather like the rudder on a boat.
Following trials, Little Willie had passed all the tests it had been designed for. The way was now open for the production of the next machine – 'Mother', the world's first fighting tank.