Nor would it be safe to rely upon the vulnerability of the tank remaining as low as at present.' The history of military inven- tion shows us that the missile and the protection against it alternately obtain the mastery. At present, so far as the tank is concerned, the latter is in the ascendent, but the study of anti-tank methods has hardly been begun. A metal machine, which is as conspicuous as the tank, presents certain very weak points of attack to modern science, with electricity, magnetism, and automatic ranging at its command. It may confidently be asserted that in the future anti-tank methods will develop more quickly than the tank itself; but it must also be pointed out that they have much leeway to make up.
Apart from the above question of development the tank possesses an inherent disadvantage in that the force which it represents is very highly concentrated. Tanks will not be able to hold positions even if they take them. For at night or in fog an enemy, if he chooses to attack in great superiority, will get through any line which is not held continuously by men sta- tioned almost at arm's length from one another. The essence of success, for this reason, lies in the concentration of superior man-power at the decisive point; and in the future, as in the past, the role of all arms other than infantry and cavalry will be the subsidiary one of facilitating that operation. In the actual attack, too, a lucky shot, putting a tank out of action, destroys a much larger proportion of the force than would the same shot striking the equivalent body of cavalry, which would be dis- persed. This disadvantage of over-concentration, aggravated as it is by the conspicuous character of the tank, will not dis- appear until a machine is produced which provides complete protection for single men, and so allows of dispersion; and this is an event which is very far distant.
Nevertheless, where an attack on trenches is concerned, and especially on those protected by wire, the tank is immeasurably superior to cavalry. In war it will often fall to the lot of cavalry formations to make such an attack, and it is here that tanks may well replace a part of the cavalry, the remainder being employed in assailing the weaker parts of the enemy's front, in holding the position when taken, and in rounding up fugitives, for which again dispersion is necessary. In the World War armoured cars were often used with success for conveying special officers from place to place under fire, and for early- morning reconnaissance, when it was desired simply to locate an enemy with whom touch had been temporarily lost. In the next war fast tanks will replace the armoured car for these purposes. But for the more detailed reconnaissance which usually follows, armoured cars, and tanks also, are unsuitable, by reason of their vulnerability when stationary and the limited range of vision which is obtainable from inside them. In the future then, tanks will not usurp the functions of mounted troops, but on the contrary will widen their scope by relieving them from the necessity of attacking, or of waiting for infantry to attack, organized positions. A force of tanks, fully as mobile in every respect as the horse, will be attached to all higher cavalry formations.
The influence of the second new development, the cross- country tractor, will be wholly in favour of mounted troops. In the past one of the chief obstacles to the employment of cavalry has been the difficulty of supplying them, and the length of road space which the subsidiaries, artillery, engineers, and rearward services, take up. This probably is one of the reasons for the German cavalry showing up so little during the retreat from Mons, and for their not being employed at all to confirm the success gained in March 1918, when, according to Sir Douglas Haig, " their presence could not have failed to have added greatly to the difficulties of our task." Cross-country tractors, independent of roads, carrying supplies of all sorts, and perhaps dragging the guns, will greatly enlarge the radius of action.
Of all novelties in warlike organization, the aeroplane is the most serious rival to cavalry. It has already taken over to a great extent the duties of reconnaissance which were formerly performed almost exclusively by mounted troops. The service of discovering the direction of the enemy's principal concentra-
tions, whether by road or by rail, and of reporting upon his entrenchments, gun positions, and larger activities generally, is now carried out from the air. This was formerly the province of the independent cavalry, which was consequently made as strong as possible. Now, owing to the advent of the aeroplane, the proportion of cavalry allotted to independent work will be relatively smaller, except in the case of a pursuit, and the bulk of the horse soldiers will be employed on missions which are protective in character. It must not be supposed, however, that the service of reconnaissance can be carried out entirely from the air. It is difficult for aeroplanes to observe lesser details or to distinguish between friend and foe; for, if they fly so high as to be invulnerable from the ground, they can dis- tinguish nothing but heavy columns or clearly marked entrench- ments and tracks; at medium heights they were, even at the close of the late war, fairly vulnerable to anti-aircraft weapons, which are likely to improve in efficiency in the future; and at low altitudes again the very speed which protects them from anti- aircraft fire militates also against accurate observation. There- fore, for the service of reconnaissance, cavalry will still be required to supplement aircraft reports; to provide, especially in open warfare where clearly marked trenches do not exist, detailed information as to the enemy's dispositions; to secure identifica- tipns by the capture of prisoners; and, above all, to replace the aeroplane under conditions of ground or climate which are unfavourable to air reconnaissance. In this connexion it may be mentioned that, during stationary warfare in the summer of 1918 in the Jordan valley, the very efficient Air Force units attached to the Egyptian Expeditionary Force were found to be of comparatively little value for purposes of tactical reconnais- sance. The ground, precipitous, rocky, and very complicated, cast deep shadows in every direction; and in the middle of the day atmospheric conditions over the deep trough of the valley made flying almost prohibitively dangerous.
A matter for much more serious consideration by cavalrymen is the question of attack from the air. Towards the end of the war in France it became clear that troops whose location is not completely hidden are liable to be bombed at any time by day or by night, and, further, that even a superior air force is powerless to prevent such attacks. Much can of course be done by attacking the enemy's aerodromes, but the great radius of action of aircraft increases so much the value of the initiative that it is hopeless to expect, however great the superiority, to get com- mand of the air in the sense that it can be obtained by land or sea. And it is next to impossible to conceal the presence of a large number of horses. Led horses will, of course, be specially vulnerable. Given great superiority in aircraft, it may be fea- sible to provide protection by having some machines continually overhead. By day this might prove adequate, though it would entail a very great strain on the resources of the Air Force. By night it would be of little value. The true defence against air- craft, other than that of carrying the war into the enemy's country and attacking his aerodromes, is from the ground; and it must be admitted that, against an enemy with an efficient and enterprising air force, the existence in war of mounted troops will become precarious unless a great advance is made in the science of anti-aircraft defence from the ground. They must be prepared, in any case, to deliver their blow from widely separated formations, instead of massing for attack. Means of intercommunication must therefore be very specially studied and developed. It should be noted that, in the case of tanks also, the difficulty of concealment from the air will be great if they are employed in large numbers, but here it may be possible to devise some sort of portable and easily erected covering, which will provide at the same time camouflage and overhead protection. Gas attacks will be particularly dangerous to mounted troops because, though horses are less affected by gas than human beings, it is very much harder, if not impossible, to devise for them an efficient protection against it. How- ever, it is doubtful whether gas will ever become an important fac- tor in mobile warfare; and mounted troops can move compara- tively quickly out of a gas area.
