It is needless to consider cavalry, for they suffer all the disabilities, save one, of infantry, and in greater degree because they offer a larger and more vulnerable target. The sole exception is that they can run away faster! Then, with regard to field artillery――though moderately effective against the sluggish tanks of the Great War, its chances would be infinitely less against a modern tank zigzagging at over 20 m.p.h., and infinitesimal against them if launched in masses. If it cannot hit, it will be hit. In any case, its value depends on the tanks coming to meet it; its _rôle_ thus becomes purely defensive. Only by being fitted in a tank――the obvious solution――can it compel the tank to come to action, and resume its offensive _rôle_ in a war of movement. Though the tank is not yet perfect――it is only as old as the automobile of 1902, or the aeroplane of 1910――the fact that it combines in itself the three essential elements of warfare――hitting power, protection, and mobility――makes it clearly superior in normal country to any of the existing arms, which are deficient in one, or all, of these elements. To anyone who has experienced the sense of helplessness caused by the sight of the modern tanks racing towards one at 20 m.p.h., sweeping over banks and nullahs, swinging round with amazing agility in their own length, the question arises: “Can flesh and blood, however heroic, be persuaded to face them?” It is a sight to freeze the blood of a witness with imagination to grasp the demoralizing effect if their guns and machine-guns were actually spitting forth death. The tank has its limitations; there are certain types of ground on which it is handicapped――hills, woods, and swamps, and certain defences against which it is helpless. By taking advantage of such partially tank-proof terrain, infantry may survive for a time. But the limitations of the tank are exaggerated by the fact that its tactics have not been thought out and adapted to its qualities and limitations. Regarded as a mere prop to an arm――infantry――too helpless to look after itself, it has been frittered away in driblets or under unsuitable conditions――as in the swamps of Passchendaele. To discover its true use let me suggest an historical parallel: The military bulwark of the Roman Empire was its legions, for six centuries the “queen of battle,” defying all efforts to oppose them by like means. On the _9th August, 378_ A.D., on the plains of Adrianople, they met a new challenge――the cavalry of the Goths. “The Goths swept down on the flank of the Roman infantry, so tremendous was the impact that the legions were pushed together in helpless confusion.... Into this quivering mass the Goths rode, plying sword and lance against the helpless enemy.” When the sun went down that evening, it set not only on the great Roman Empire, but on the reign of infantry――the instrument and token of Roman world-power. The age of cavalry was ushered in.