Churchill wanted land battleships. Unfortunately, since soil and rock tends to lack the consistency of seawater, what he got was a land Baseplate; famously named to trick wielders into thinking they were making super-gun artillery baseplates.
The Mark 1 Baseplate weighed 200 tons, half of which was the double engine 5,000hp steam turbine power plant, carried four 6 pounder guns, and 10 machine guns. The thirty man crew could manoeuvre it over rough ground (and even water!) at a speed of 15 MPH, while the armour plate was capable of standing up to even heavy german machine gun fire. The shear size also gave limited protection from light artillery, since any given hit was often ten yards away from anything else.
Sadly mechanical defects, notably related to the steam safety valve and governor system, impeded the success of their first use during the battle of the Somme. Of 12 deployed units, 7 experienced technical problems, and all experienced pressure losses due to machine gun damage to their kilts. This was anticipated, and repairs proved remarkably easy, even in enemy territory due to overwhelming covering fire provided by each Baseplate's guns.
The Mark 1 was limited to a mere 4 hours of operation due to the size of its coal bunkers, but this was remidied in the Mark III design onwards by a switch to heavy fuel oil. (This allowed for some experimentation with flame throwers, which was soon abandoned as ineffective.)
Though the Mark 1s became a symbol of the Western Front, and later of Victory on the Western Front, credit is more properly applied to the Mark IV Dragoon carrier. Fitted with a single engine, machine gun nest, and little armour, it could carrier a whole platoon of soldiers 200 miles at 40mph across all terrain. Quickly named the Hurricane by Imperial troops, riding in one at top speed was described as an unforgettable experience, and soldiers were sometimes uncertain whether it did more damage to the enemy, the land it rode over, or the poor tommies who had to ride inside it.
By the end of the war both Germany and France were working on their own versions of Baseplate and Hurricane, but starvation on the German Homefront brought the war to a close before they could see active service. After the war the technology fell into disfavour with the British & French, under intense lobbying from the cavalry, who didn't want to be replaced or supplemented, and was barred to the Germans. At least until the 1930s when Hitler came to power, and demonstrated the devastating combination of high speed mechanised dagoons combined with the ruthless professionalism of stormtrooper tactics, during the invasions of 1939.
One final footnote in the early history of Baseplate technology should go to a little known machine called Little Willie (abandoned due to unresolvable CoG problems) which was in many ways a fore runner of the modern (1970s onwards) American GPTP (Gun Platform Track Propelled) family of armoured cars. Military historians will knowingly roll their eyes and calmly label this yet another example of innovative technology wasted upon the British government.
It would be interesting to consider what might have been if the British had been able to successfully deploy GPTP technology during the war in addition to, or instead of Baseplate technology. Though such speculation is, of course, beyond the scope of this article.