January 5, London—Winston Churchill had taken an interest in finding paths to an Allied victory that did not involve British infantry “chew[ing] barbed wire in Flanders.” One approach that he considered was the development of some sort of armored machine to cross trenches—what would become the tank. In late December, Churchill read a paper by Col. Maurice Hankey proposing various “mechanical devices” that could be useful in the current war. This inspired him to write the following letter to PM Asquith on January 5:

I entirely agree with Colonel Hankey’s remarks on the subject of special mechanical devices for taking trenches. It is extraordinary that the Army in the Field and the War Office should have allowed nearly three months of trench warfare to progress without addressing their minds to its special problems.

The present war has revolutionised all military theories about the field of fire. The power of the rifle is so great that 100 yards is held sufficient to stop any rush, and in order to avoid the severity of the artillery fire, trenches are often dug on the reverse slope of positions, or a short distance in the rear of villages, woods or other obstacles. The consequence is that the war has become a short range instead of a long range war as expected, and opposing trenches get ever closer together for mutual safety from each other’s artillery fire. The question to be solved is not therefore the long attack over a carefully prepared glacis of former times, but the actual getting across of 100 or 200 yards of open space and wire entanglements. All this was apparent more than two months ago, but no steps have been taken and no preparation made. It would be quite easy in a short time to fit up a number of steam tractors with small armoured shelters, in which men and machine guns could be placed, which would be bullet-proof. Used at night they would not be affected by artillery fire to any extent. The caterpillar system would enable trenches to be crossed quite easily, and the weight of the machine would destroy all wire entanglements. Forty or fifty of these engines prepared secretly and brought into position at nightfall could advance quite certainly into the enemy’s trenches, smashing away all the obstructions and sweeping the trenches with their machine gun fire and with grenades thrown out of the top. They would then make so many points d’appui for the British supporting infantry to rush forward and rally on them. They can then move forward to attack the second line of trenches. The cost would be small. It the experiment did not answer, what harm would be done? An obvious measure of prudence would have been to have started something like this two months ago. It should certainly be done now.

The shield is another obvious experiment which should have been made on a considerable scale. What does it matter which is the best pattern? A large number should have been made of various patterns; some to carry, some to wear, some to wheel. If the mud now prevents the workings of shields or traction engines, the first frost would render them fully effective. With a view to this I ordered a month ago twenty shields on wheels to be made on the best design the Naval Air Service could devise. These will be ready shortly, and can, if necessary, be used for experimental purposes.

A third device which should be used systematically and on a large scale is smoke artificially produced. It is possible to make small smoke barrels which on being lighted generate a great column of dense black smoke which could be turned off or on at will. There are other matters closely connected to this to which I have already drawn your attention, but which are of so secret a character that I do not put them down on paper.

One of the most serious dangers that we are exposed to is the possibility that the Germans are acting and [are] preparing all of these surprises, and that we may at any time find ourselves exposed to some entirely new form of attack. A committee of engineer officers and other experts ought to be sitting continually at the War Office to formulate schemes and examine suggestions, and I would repeat that it is not possible in most cases to have lengthy experiments beforehand. If the devices are to be ready by the time they are required it is indispensable that manufacture should proceed simultaneously with experiment. The worst that can happen is that a comparatively small sum of money is wasted.