For by 1914 the Tank had successively passed through several tentative and inconclusive incarnations.
In 1482 Leonardo da Vinci invented a kind of Tank;[1] a wooden “War Cart” was used by the Scottish in the fifteenth century.[2]
There were designs for a Tank for the Crimea, but the project of this weapon was abandoned as being barbarous. Lastly, a really practical design for a kind of “Caterpillar” to be driven by steam was made in 1888. A trial machine was even constructed. But Fate decreed that all trace of design and model should be instantly lost, only apparently to be rediscovered after the modern Tank had been thought out afresh.
Why, if the Tank was constantly being invented, did it as constantly disappear? The reason appears to have been that, like the early aeroplanes, all these abortive machines had failed in one particular.
The engine was not powerful enough. The steam Tank had not in the least answered the riddle. The horse-power could, it is true, be almost indefinitely increased, but, like a kind of Old Man of the Sea, the engine weight would have increased proportionately and the “free” power have been no more.
Indeed till the invention of the petrol engine the Tank was doomed to be unpractical. Its three essentials—armour-plating, guns, and ability to surmount obstacles and traverse open country—demanded a large amount of this “free” power.
Only, therefore, when an engine was produced whose proportion of power to weight was about 100 H.P. to every ten hundredweight, did the Tank become a possible and effective engine of war.
Thus, till the time was ripe the Tank had been doomed to enjoy very brief excursions into the actual, and to sojourn, long forgotten, beyond the waters of Lethe.
Does memory survive transmigration? Were General Swinton and his co-inventors aware of the Crimea Tank and the 1888 Tractor? In any case the matter is not one of great importance, for—to put it briefly—ultimately their Tank went, and the others did not.
By October, 1914, Colonel Swinton and Captain Tulloch had independently worked out the details of an engine of war. Like the other early inventors, they imagined a machine that was to “arise” out of a cross between an armoured car and an agricultural tractor. It was to be slower, more formidable and far heavier than any armoured car that had yet been seen, a kind of “Land Cruiser” capable of plodding on its caterpillar feet across country right up to the enemy’s gun positions. Like the other early “mobile machine-gun destroyers,” it was to be strongly armed with guns and machine-guns, and so heavily steel-plated as to be impervious to shrapnel, H.-E. fragments and rifle bullets. It was to cross trenches with ease, and was to be capable either of cutting or of flattening the enemy’s wire in the mere act of its progress.