AIRCRAFT IN WARFARE.*

Mn. LANCHESTER is so well known as a scientific experimenter in aerodynamics that his book on the uses of aircraft in war

will be read eagerly, as coming from one who speaks with authority and not as the "scribes "—whom, by the way, both he and Sir David Henderson in his preface belabour mercilessly. Sir David Henderson in his pungent manner says :-

" Any plausible rogue, gifted with sufficient assurance, and aided by a ready pen or supple tongue, has been able to pose as an aero- nautical expert,' and to find some kind of following. To those who, as a matter of duty, or in search of information, have perused the aeronautical discussions carried on in the Press, or the reports of such discussions elsewhere, the very word expert' calls up a strange procession of inventors, politicians, motor-trade touts, journalists, trick-fliers, novelists and financial agents, most of them, axe in hand, on the way to the national grindstone ; a few, innocent, following on the same track, on a vague quest for supernatural powers of flight. As a matter of fact, there are no experts in military aeronautics. There are experts in the various branches : in flying, in scientific research, in the design and construction of aeroplanes and engines, in military organisation and tactics. But, as yet, there is little opportunity for the expert in one branch to gain definite knowledge of the others, except by hard personal experience ; in every direction there is progress, in every section of work opinion is fluid, and the views of the workers are not yet sufficiently crystallised to permit of definite instruction to others."

Sir David Henderson does not agree with Mr. Lanchester in all respects, but he is unable to discuss most of the points of dis-

agreement, as both of them are bound by secrecy as to many new plans, theories, and discoveries—the one as Director- General of Military Aeronautics, the other as a member of the Advisory Committee for Aeronautics. On one matter, however, Sir David Henderson feels free to express his dissent. In considering the proportion of aircraft required for an army in the field, Mr. Lanchester compares aircraft with cavalry and the aeroplane with a single trooper. Sir David Henderson points out that this is no basis for calculation. Each aeroplane absorbs, on an average, the services of some twelve officers and men, and its cost would provide more than a score of horses. The only safe line, therefore, in his opinion, is first to decide exactly what services aeroplanes are required to perform, and then to decide how much of our available resources wo are justified in devoting to them. A balance, in fact, must be struck. Whether Mr. Lanohester goes further than Sir David Henderson, or not so far, in his belief in the aeroplane, we have, however, no means of knowing. His book is proof, as we shall see, that he expects aircraft to revolutionize some aspects of war.

Mr. Lanchester dismisses dirigible balloons without much attention. He admits the mischief they can do in favourable circumstances by night, but his business is to consider aircraft • Airrraft in Warfare: the Dawn of the Fourth Arm. By F. W. Lancheater. With Introductory Preface by Major-General Sir David Henderson, K.C.B.

London: Constable and Co. ed. net.]

from the point of view of advancing the science of war and winning campaigns. _In this respect he sees no future for the Zeppelins. He thinks that the Germans have not only put their money en the wrong horse, but have wasted much time and energy which might have been applied to the more profitable

development of their aeroplanes. His account of our own aeronautical science and the practical ability of our airmen is extremely flattering. We have gained the supremacy of the air, though ho holds that we shall need all our available money and all our perseverance to maintain it. He points out that many aeroplanes can now climb at a speed of seven or eight hundred feet a minute, " thus being more than able to hold their own with the lighter-than-air Machine." Ho thinks that in daylight no dirigible can stand against an airman if the airman has a powerful machine of modern design and is prepared to sacrifice himself in the fatal act of ramming his enemy. In very few respects does Mr. Lanchester admit superiority in the use or equipment of German aeroplanes. He admires, however, the German methods of signalling information to the artillery :-

" The exact mode or modes of signalling adopted do not so far appear to have been definitely disclosed. Some reports give the aeroplane as turning sharply when over the enemy's position ; according to other accounts a smoke bomb of some kind is let fall to indicate the position to be attacked ; other reports, again, mention lights as being used. It appears that lamps of sufficient power to be visible in daylight are actually being employed by the German aircraft."

The difficulties which artillerists have to contend with in firing at aeroplanes are enormous. Not. only has the gunner to fire far ahead of the swiftly moving and tiny target, but he has to allow for the earth's rotation—a matter of about thirty feet westward, which cannot be allowed for without reference to the compass bearing. As for the protection of aeroplanes against artillery, .Mr. Lanchester remarks that armour which is not absolutely proof against bullets is worse than useless. As enough of such armour could not be carried to cover all the vital parts, he concludes that the best plan is to cover the more important places. The vulnerability of aeroplanes can be greatly reduced by a comparatively small area of armour. It must be remembered that a large percentage of bullets pass harmlessly through the struts and spars of an aeroplane. But sometimes these things must be hit, and against this danger it is possible so to construct the propeller, the controls, the struts, and the wing and tail members as to make them " transparent " to bullets, That is to say, all these parts can be designed so that bullets will do only local injury. " Any intermediate course is fatal. Either the bullet must be definitely resisted and

stopped, or it must be let through with the least possible resist- ance." The designer must ..decide which policy to adopt in

respect of each component part of the machine. Mr. Lanchester believes that explosive bullets are the only means of fatally weakening a properly designed aeroplane. This may be a subject for fUture decisions in international law. Mr. Lanchestcr does not, of course, recommend that we should take the responsi- bility of breaking the present law. We should be released from the law, however, if Germany adopted the policy of using explosive bullets against aeroplanes, according to her usual doctrine of necessity.

Mr. Lanchester makes one think furiously with his visions of the future. He foresees the employment of squadrons of aeroplanes flying very low and pouring their fire into lines of infantry as they sweep past them. The aeroplanes themselves would be very hard to hit ; and though of course they would have many casualties, he thinks the percentage would be lower than in the case of the slower-moving cavalry. A cavalryman, we may remember, often attributes his immunity from harm in a desperate rush to his speed. Mr. Lanchester does not take the sensational view that aeroplanes will supersede cavalry, but he believes that they must considerably modify its practice. In writing of the strategy and tactics of aeroplanes in the future, he develops what he calls the N-square law of concentration. It applies not only to aeronguties, but to the strategy and tactics of every arm, and in practice is at least as old as Philip of Macedon ; but we do not call to mind having seen it expressed

mathematically before. We cannot enter into the mathematical proof, but let us quOte what Mr. Lanchester says as to a deduction frOm the law :- " Evidently it is the business of a numerically superior force to come to close quarters, or, at least, to get within decisive range as --rapidly as possible, in order that the concentration may tell to advantage. As an extreme case let us imagine a ' Blue' force of 100 men armed with the machine gun opposed by a ' Red' 1,200 men armed with the ordinary service rifle. Our firpt assumption will be that both forces are spread over a front of given length and at long range. Then the ' Red ' force will lose 16 men to the ' Blue' force loss of one, and, if the combat is continued under these con- ditions, the Reds ' must lose. If, however, the 'Reds' advance, and get within short range, where each man and gunner is an indi- vidual mark, the tables are turned, the previous equation and con- ditions apply, and, even if Reds' lose half their effective in gaining the new position, with GOO men remaining they are masters of the situation ; their strength is 6002 x I against the Blue ' 1001 x 18. It is certainly a not altogether expected result that, in the case of fire so deadly as the modern machine gun, circumstances may arise that render it imperative, and at all costs, to come to close range."

In the author's opinion, we have not yet enough aeroplanes to justify us in saying that the Fourth Arm has been created. But when it is created it will be so important, in his judgment, that nothing will be able to compensate us for the loss of the supremacy of the air. We shall talk of that supremacy, if he is right, as we now talk of naval supremacy. To lose it will be to lose all. By way of illustration he compares what our airmen are able to do at the front with what they might do if aeroplanes were more numerous :-

"Thus, in the existing phase of the present war, were our aircraft of sufficient numerical strength, it would no longer be a matter of individual and isolated raids on selected places at which the maxi- mum of injury could be inflicted, but rather a continuous and unrelenting attack on each and every point of strategic importance. Depots of every kind in the rear of the enemy's lines would cease to exist ; rolling stock and mechanical transport would be destroyed ; no bridge would be allowed to stand for 24 hours ; railway junctions would be subject to continuous bombardment, and the lines of railway and roads themselves broken up daily by giant bombs to such an extent as to baffle all attempts to maintain or restore com- munication. In this manner a virtually impassable zone would be created in the rear of the enemy's defences, a zone varying, perhaps, from 100 to 200 miles in width. Once this condition has been brought about the position of the defending force must be considered as precarious ; not only will the defence be slowly strangled from the uncertainty and lack of supplies of all kinds, but ultimately retreat will become impossible."

Finally, we may mention one possible result of the growing range of air offence. Our great naval docks will have to be placed as remote as possible from the Continent of Europe—say at Belfast and in the Clyde—and a ship canal from the Clyde to the Forth will be even more necessary to us than the Kiel Canal was to the Germans.