The Mark IV was the main tank in service during 1917. In two short years, how did the tank used at Cambrai differ from its predecessor, Little Willie?
Little Willie, as it exists, is its second manifestation, but in this form was the first tank to be fitted with William Tritton’s new tracks, and as such is as good a place to start as any when reviewing tank development up to the summer of 1917.
However by the time they’d got it running, a new design was nearly completed, so Little Willie was effectively out of date, even while it was doing its first trials. These took place in Burton Park, Lincoln, towards the end of 1915 and although by this time Little Willie had a new tail assembly, the dummy turret had been removed and it was only really acting as a test bed for the new tracks.
Inside it was powered by a Daimler six-cylinder engine driving through a two-speed and reverse gearbox and differential, so in that respect it had features in common with the tanks that were actually used in action.
Little Willie to Mother
Little Willie was replaced by a machine that came to be known as Mother, built to a design worked out by the engineer W. G. Wilson, then serving as a Lieutenant in the Royal Naval Air Service. It was a striking design when compared with Little Willie, its track frames had been enlarged and extended, carrying the tracks (which were to William Tritton’s design) all the way round the hull.
Between the frames the hull itself was a box, not unlike that carried by Little Willie, and since a turret would have been too high and directly above the engine, weapons were mounted in sponsons, attached to each side. On the interior the Daimler engine was retained, but repositioned, as was the gearbox and differential, but two extra speeds were fitted on the ends of the output shafts, because at 28 tons the new machine was too heavy for the original gearbox alone.
Mother was essentially the same as the first batch of production tanks although these, of which 150 were built, were divided into male and female types, 75 of each. Male tanks had sponsons like Mother, each one mounting a 57mm, six-pounder gun. Female tanks, on the other hand, each mounted two cumbersome sponsons, designed to carry two Vickers, water-cooled, heavy machine guns instead, with tiny escape doors at the back.
These, the Mark I tank, had a number of detail differences from Mother although they retained the same engine and drive train and the same eight-man crew, four of whom were needed for driving.
Again, like Mother, they had a wheeled tail assembly at the back which could be used for steering and as a counter-balance when going over a ridge or even additional support when crossing a wide trench.
It was tanks of this type, suitably camouflage painted, that went into action for the first time on 15 September 1916 on the Somme. Eight others were shipped out to Palestine and saw action at Gaza, the first time tanks were ever used in a desert setting. Later in 1916 the wheeled tails, which were proving more trouble than they were worth, were removed and it was found that the tanks ran just as well without them.
Other modifications included fitting stronger brakes and better track rollers and removing the teeth from the idler wheels at the front. Some minor actions took place later in the year and fifteen Mark I tanks were earmarked to take part in the Battle of Arras in April 1917. After that, as new tanks were coming along the surviving Mark Is were relegated to subsidiary roles as Supply or Wireless tanks.
The Oldbury Trials
Oldbury, just outside Birmingham, was where the transmission trials were held on 3 March 1917. Among the weird and wonderful contestants was one, designed by W. G. Wilson, that employed epicyclic gears for steering. This was judged to be the best but it came too late for any of the tanks now on order although it was earmarked for the Mark V tank that would be completed in 1918.
Meanwhile a new tank, designated Mark IV was being built in large numbers for service in 1917. Huge orders were placed and a number of additional factories were recruited to build them, including some famous names in Scotland. But it still used the Daimler engine and the same four-man driving technique of the earlier tanks.
Once again male and female tanks would be required although the design of the sponsons was changed and the American Lewis gun was chosen as the secondary armament, as well as for female tanks in place of the big water-cooled Vickers.
Sponsons were now designed to be folded into the tanks for travelling by rail, hitherto sponsons had to be unbolted and lifted off, a time consuming operation when tanks were moved by rail. Early tanks also had a pair of petrol tanks either side of the cab that proved to be a death trap if they caught fire as the men were getting out.
On the Mark IV a larger petrol tank was carried at the back, where the tail used to be. There were many other improvements too, thicker armour, and a new petrol supply system among others.
Tanks were still prone to go wrong, some would not start at all while others broke down although this was invariably due to inadequate preparation, and as the number of tanks increased the proportion that broke down seemed fewer, added to which as crews became more experienced they learned to anticipate trouble and how to cure it.
The Mark IV would be the main British tank for service in 1917 and the early part of 1918. It would be used in the mud of Third Ypres and in the epoch making Battle of Cambrai, which was a runaway success to begin with.
Read David Fletcher’s article on Little Willie here.