On January 18, 1915, before British tanks had been invented, the First Lord of the Admiralty, Winston Spencer Churchill, sent an instruction to the Third Sea Lord: “I wish the following experiment made at once. Two ordinary steam rollers are to be fastened together side by side with very strong steel connections so that they are to all intense and purposes one roller covering a breadth of at least 12 to 14 feet.
“If convenient, one of the back inside wheels might be removed and the other axle joined up to it. Some trenches are to be dug on the latest principles somewhere handy near London in length of at least 100 yards, the earth is taken out of the trenches being thrown on each side, as is done in France.
‘The object is to ascertain what amount of weight is necessary for the roller to smash that trench in’
“The roller is to be driven along these trenches, one outer rolling wheel on each side, and the inner rolling will just clear the trench itself. The object is to ascertain what amount of weight is necessary for the roller to smash that trench in.