As a highly irresponsible prophet I am convinced that towards the end of the war hostilities in the air will become as decisive as hostilities on land or sea. An obvious corollary is that the how and when of peace's coming must be greatly influenced by the respective progress, during the next two years, of the belligerents' flying services.

This view is far less fantastic than the whirlwind development of war-flying witnessed by all of us since 1914. Indeed, to anybody with a little imagination and some knowledge of what is in preparation among the designers and inventors of various countries, that statement would seem more self-evident than extreme. Even the average spectator of aeronautical advance in the past three years must see that if anything like the same rate of growth be maintained, by the end of 1918 aircraft numbered in tens of thousands and with extraordinary capacities for speed, climb, and attack will make life a burden to ground troops, compromise lines of communication, cause repeated havoc to factories and strongholds, and promote loss of balance among whatever civilian populations come within range of their activity.

To emphasise the startling nature of aeronautical expansion—past, present, and future—let us trace briefly the progress of the British Flying Corps from pre-war conditions to their present state of high efficiency. When the Haldane-Asquith brotherhood were caught napping, the Flying Corps possessed a seventy odd (very odd) aeroplanes, engined by the unreliable Gnome and the low-powered Renault. Fortunately it also possessed some very able officers, and these succeeded at the outset in making good use of doubtful material. One result of the necessary reconstruction was that a large section of the original corps seceded to the Navy and the remainder came under direct control of the Army. The Royal Naval Air Service began to specialise in bomb raids, while the Royal Flying Corps (Military Wing) sent whatever machines it could lay hands on to join the old contemptibles in France. Both services proceeded to increase in size and importance at break-neck speed.

The rapid expansion of the R.N.A.S. allowed for a heavy surplus of men and machines beyond the supply necessary for the purely naval branch of the service. From this force a number of squadrons went to the Dardanelles, Africa, the Tigris, and other subsidiary theatres of war; and an important base was established at Dunkirk, whence countless air attacks were made on all military centres in Belgium. Many more R.N.A.S. squadrons, well provided with trained pilots and good machines, patrolled the East Coast while waiting for an opportunity of active service. This came early in 1917, when, under the wise supervision of the Air Board, the section of the Naval Air Service not concerned with naval matters was brought into close touch with the Royal Flying Corps, after it had pursued a lone trail for two years. The Flying Corps units on the Western Front and elsewhere are now splendidly backed by help from the sister service. For the present purpose, therefore, the military efforts of the R.N.A.S. can be included with those of the R.F.C., after a tribute has been paid to the bombing offensives for which the Naval Air Service has always been famous, from early exploits with distant objectives such as Cuxhaven and Friedrichshafen to this year's successful attacks on German munition works, in conjunction with the French, and the countless trips from Dunkirk that are making the Zeebrugge-Ostend-Bruges sector such an unhappy home-from-home for U-boats, destroyers, and raiding aircraft. Meanwhile the seaplane branch, about which little is heard, has reached a high level of efficiency. When the screen of secrecy is withdrawn from the North Sea, we shall hear very excellent stories of what the seaplanes have accomplished lately in the way of scouting, chasing the Zeppelin, and hunting the U-boat.

But from the nature of its purpose, the R.F.C. has borne the major part of our aerial burden during the war. In doing so, it has grown from a tiny band of enthusiasts and experimentalists to a great service which can challenge comparison with any other branch of the Army. The history of this attainment is intensely interesting.

The few dozen airmen who accompanied the contemptible little army on the retreat from Mons had no precedents from other campaigns to guide them, and the somewhat vague dictum that their function was to gather information had to be interpreted by pioneer methods. These were satisfactory under the then conditions of warfare, inasmuch as valuable information certainly was gathered during the retreat, when a blind move would have meant disaster,—how valuable only the chiefs of the hard-pressed force can say. This involved more than the average difficulties, for as the battle swayed back towards Paris new landing-grounds had to be sought, and temporary aerodromes improvised every few days. The small collection of serviceable aeroplanes again justified themselves at the decisive stand in the Marne and Ourcq basin, where immediate reports of enemy concentrations were essential to victory. Again, after the Hun had been swept across the Aisne and was stretching north-eastward tentacles to clutch as much of the coast as was consonant with an unbroken line, the aerial spying out of the succeeding phases of retirement was of great service. Indeed, tentative though it was, the work of the British, French, and German machines before the advent of trench warfare proved how greatly air reconnaissance would alter the whole perspective of an open country campaign.

After the long barrier of trenches deadlocked the chances of extended movement and opened the dreary months of more or less stationary warfare, the R.F.C. organisation in France had time and space for self-development. Aerodromes were selected and erected, the older and less satisfactory types of machine were replaced by the stable B.E2.C., the active service squadrons were reconstructed and multiplied.

To the observation of what happened behind the actual front was added the mapping of the enemy's intricate trench-mosaic. For a month or two this was accomplished by the methodical sketches of a few observers. It was an exceedingly difficult task to trace every trench and sap and to pattern the network from a height of about 2000 feet, but the infantry found small ground for dissatisfaction as regards the accuracy or completeness of the observers' drawings. Then came the introduction of aerial photography on a large scale, and with it a complete bird's-eye plan of all enemy defence works, pieced together from a series of overhead snapshots that reproduced the complete trench-line, even to such details as barbed wire. By the infallible revelations of the camera, untricked by camouflage, concealed gun positions were spotted for the benefit of our artillery, and highly useful information about likely objectives was provided for the bombing craft.

The frequent bombing of German supply centres in Belgium and North France came into being with the development of aerial photography. Owing to the difficulty of correct aim, before the advent of modern bomb-sights, all the early raids were carried out from a low altitude, sometimes from only a few hundred feet. For every purpose, moreover, low altitudes were the rule in the earlier months of the war, as most of the machines would not climb above 4000-7000 feet. Much of the observation was performed at something between 1000 and 2000 feet, so that aircraft often returned with a hundred or so bullet-holes in them.

Meanwhile the important work of artillery spotting was being developed. New systems of co-operation between artillery and aeroplanes were devised, tested, and improved. At first lamps or Very's lights were used to signal code-corrections, but these were soon replaced by wireless transmission from the observation machine. Targets which could not be ranged on through ground observation posts became targets no longer, after one shoot ranged from the air. As the number of available aircraft increased, so did the amount of observation for the guns, until finally the entire front opposite the British was registered for bombardment and divided into sections covered by specified artillery machines.

Aerial fighting, now so essential and scientific a branch of modern war, was rudimentary in 1914. Pilots and observers of the original Flying Corps carried revolvers, and many observers also equipped themselves with rifles, but the aeroplanes were not fitted with machine-guns. Such scraps as there were consisted of one machine manoeuvring round an opponent at close quarters for the chance of a well-aimed shot. Under these circumstances to "bring down" or "drive down out of control" an enemy was extremely difficult, though a very gallant officer, since killed in action, once killed two German pilots within five minutes with his revolver.

Soon the possibilities of aerial machine-guns were quickly recognised. The R.F.C. adopted the Lewis, which from the points of view of lightness and handiness was well suited for aircraft, and the German airmen countered with a modified Hotchkiss and other types.

But the stable observation machines, while excellent for reconnaissance and artillery spotting, allowed their crews only a small arc of fire, and not until the German single-seater scouts and our Bristol scout, then a comparatively fast machine, appeared on the western front in the spring of 1915 did the destruction of aeroplanes become an everyday occurrence. With the introduction of scouts for escort and protective duties came formation flying and concerted attack.

Fighting craft continued to increase in speed and numbers. As the struggle became more and more intense, so did the scene of it move higher and higher, prodded by an ever-growing capacity for climb and the ever-growing menace of the anti-aircraft guns. The average air battle of to-day begins at an altitude between 12,000 and 20,000 feet.

The conflict for mechanical superiority has had its ebb and flow, and consequently of its proportional casualties; but the British have never once been turned from their programme of observation. There have been critical times, as for example when the Fokker scourge of late 1915 and early 1916 laid low so many of the observation craft. But the Fokkers were satisfactorily dealt with by the de Haviland and the F.E.8. pusher scouts and the F.E. "battleplane," as the newspapers of the period delighted to call it. Next the pendulum swung towards the British, who kept the whip hand during the summer and autumn of last year. Even when the Boche again made a bid for ascendancy with the Halberstadt, the Roland, the improved L.V.G., and the modern Albatross scout, the Flying Corps organisation kept the situation well in hand, though the supply of faster machines was complicated by the claims of the R.N.A.S. squadrons in England.

Throughout the Somme Push we were able to maintain that aerial superiority without which a great offensive cannot succeed. This was partly the result of good organisation and partly of the fighting capabilities of the men who piloted the Sopwith, the Nieuport, the de Haviland, the F.E., and other 1916 planes which were continually at grips with the Hun. The German airmen, with their "travelling circuses" of twelve to fifteen fast scouts, once more had an innings in the spring of the current year, and the older types of British machine were hard put to it to carry through their regular work. Then came the great day when scores of our new machines, husbanded for the occasion, engaged the enemy hell-for-leather at his own place in the air. An untiring offensive was continued by our patrols, and the temporary supremacy passed into British hands, where it very definitely remains, and where, if the shadows of coming events and the silhouettes of coming machines materialise, it is likely to remain.

Judged on a basis of losses, the unceasing struggle between aeroplane and aeroplane would seem to have been fairly equal, though it must be remembered that three-quarters of the fighting has had for its milieu the atmosphere above enemy territory. Judged on a basis of the maintenance of adequate observation, which is the primary object of aerial attack and defence, the British have won consistently. At no time has the R.F.C. been obliged to modify its duties of reconnaissance, artillery spotting, photography, or co-operation with advancing infantry, which was introduced successfully last summer. On the contrary, each of these functions, together with bombing and "ground stunts" from low altitudes, has swollen to an abnormal extent.

An idea of the vastness of our aerial effort on the British front in France can be gathered from the R.F.C. work performed on a typical "big push" day.Throughout the night preceding an advance, several parties, laden with heavy bombs, steer by compass to Hun headquarters or other objectives, and return no longer laden with bombs. The first streak of daylight is the herald of an exodus from west to east of many score fighting craft. These cross the lines, hover among the Archie bursts, and drive back or down all black-crossed strangers within sight. Some of them go farther afield and attack the Boche above his own aerodromes. Such enemy craft as manage to take the air without meeting trouble from the advanced offensive patrols are tackled by the scouts near the lines. The few that travel still farther eastward with the intention of swooping on our observation machines, or of themselves gathering information, receive a hearty welcome from our defensive patrols.

The British two-seaters are thus free to direct the artillery, link the attacking infantry with headquarters, and spy out the land. As soon as the early morning light allows, a host of planes will be darting backward and forward over the trench-line as they guide the terrific bombardment preliminary to an attack. Other machines are searching for new emplacements and signs of preparation behind the enemy trenches. Several formations carry out tactical reconnaissances around an area stretching from the lines to a radius twenty miles east of them, and further parties perform strategic reconnaissance by covering the railways, roads, and canals that link the actual front with bases thirty to ninety miles behind it. When, at a scheduled time, the infantry emerge over the top behind a curtain of shells, the contact patrol buses follow their doings, inform the gunners of any necessary modifications in the barrage, or of some troublesome nest of machine-guns, note the positions held by the attackers, collect signals from the battalion headquarters, and by means of message bags dropped over brigade headquarters report progress to the staff. If, later, a further advance be made, the low-flying contact machines again play their part of mothering the infantry.

Machines fitted with cameras photograph every inch of the defences improvised by the enemy, and, as insurance against being caught unprepared by a counter-attack, an immediate warning of whatever movement is in evidence on the lines of communication will be supplied by the reconnaissance observers. Under the direction of artillery squadrons the guns pound the new Boche front line and range on troublesome batteries.

The bombing craft are responsible for onslaughts on railways, supply depÔts, garrison towns, headquarters, aerodromes, and chance targets. Other guerilla work is done by craft which, from a height of anything under a thousand feet, machine-gun whatever worthwhile objects they spot. A column of troops on the march, transport, ammunition waggons, a train, a stray motor-car—all these are greeted joyfully by the pilots who specialise in ground stunts. And at every hour of daylight the scouts and fighting two-seaters protect the remainder of the R.F.C. by engaging all Huns who take to the air.

Doubtless, when sunset has brought the roving birds back to their nest, there will be a few "missing"; but this, part of the day's work, is a small enough sacrifice for the general achievement—the staff supplied with quick and accurate information, a hundred or two Boche batteries silenced, important works destroyed, enemy communications impeded, a dozen or so black-crossed aeroplanes brought down, valuable photographs and reports obtained, and the ground-Hun of every species harried.

The German Flying Corps cannot claim to perform anything like the same amount of aerial observation as its British counterpart. It is mainly occupied in fighting air battles and hampering the foreign machines that spy on their army. To say that the German machines are barred altogether from reconnaissance and artillery direction would be exaggeration, but not wild exaggeration. Seldom can an enemy plane call and correct artillery fire for longer than half an hour. From time to time a fast machine makes a reconnaissance tour at a great height, and from time to time others dart across the lines for photography, or to search for gun positions. An appreciable proportion of these do not return. Four-fifths of the Hun bomb raids behind our front take place at night-time, when comparative freedom from attack is balanced by impossibility of accurate aim. Apart from these spasmodic activities, the German pilots concern themselves entirely with attempts to prevent allied observation. They have never yet succeeded, even during the periods of their nearest approach to the so-called "mastery of the air," and probably they never will succeed. The advantages attendant upon a maintenance of thorough observation, while whittling down the enemy's to a minimum, cannot be overestimated.

To determine how much credit for the brilliant achievement I have tried to outline belongs to the skill and adaptability of British airmen, and how much to successful organisation, would be difficult and rather unnecessary. But it is obvious that those who guided the R.F.C. from neglected beginnings to the status of a great air service had a tremendous task. Only the technical mind can realise all that it has involved in the production of trained personnel, aeroplanes, engines, aircraft depÔts, aerodromes, wireless equipment, photographic workshops and accessories, bombs, and a thousand and one other necessaries.

Many thousand pilots have been trained in all the branches of war flying. The number of squadrons now in France would surprise the layman if one were allowed to make it public; while other squadrons have done excellent work in Macedonia, Egypt, Mesopotamia, East Africa, and elsewhere. Mention must also be made of the Home Defence groups, but for which wholesale Zeppelin raids on the country would be of common occurrence.

How to make best use of the vast personnel in France is the business of the staff, who link the fighting members of the corps with the Intelligence Department and the rest of the Army in the field. To them has fallen the introduction and development of the various functions of war aircraft, besides the planning of bomb raids and concerted aerial offensives. On the equipment side there is an enormous wastage to be dealt with, and consequently a constant cross-Channel interchange of machines. The amount of necessary replacement is made specially heavy by the short life of effective craft. A type of machine is good for a few months of active service, just holds its own for a few more, and then becomes obsolete except as a training bus. To surpass or even keep pace with the Boche Flying Corps on the mechanical side, it has been necessary for the supply department to do a brisk trade in new ideas and designs, experiment, improvement, and scrapping.

Although free-lance attacks by airmen on whatever takes their fancy down below are now common enough, they were unknown little over a year ago. Their early history is bound up with the introduction of contact patrols, or co-operation with advancing infantry. Previous to the Somme Push of 1916, communication during an attack between infantry on the one hand and the guns and various headquarters on the other was a difficult problem. A battalion would go over the top and disappear into the enemy lines. It might have urgent need of reinforcements or of a concentrated fire on some dangerous spot. Yet to make known its wants quickly was by no means easy, for the telephone wires were usually cut, carrier-pigeons went astray, and runners were liable to be shot. When the British introduced the "creeping barrage" of artillery pounding, which moved a little ahead of the infantry and curtained them from machine-gun and rifle fire, the need for rapid communication was greater than ever. Exultant attackers would rush forward in advance of the programmed speed and be mown by their own barrage.

Credit for the trial use of the aeroplane to link artillery with infantry belongs to the British, though the French at Verdun first brought the method to practical success. We then developed the idea on the Somme with notable results. Stable machines, equipped with wireless transmitters and Klaxon horns, flew at a low height over detailed sectors, observed all developments, signalled back guidance for the barrage, and by means of message bags supplied headquarters with valuable information. Besides its main purpose of mothering the infantry, the new system of contact patrols was found to be useful in dealing with enemy movements directly behind the front line. If the bud of a counter-attack appeared, aeroplanes would call upon the guns to nip it before it had time to blossom.

Last September we of the fighting and reconnaissance squadrons began to hear interesting yarns from the corps squadrons that specialised in contact patrols. An observer saved two battalions from extinction by calling up reinforcements in the nick of time. When two tanks slithered around the ruins of Courcelette two hours before the razed village was stormed, the men in the trenches would have known nothing of this unexpected advance-guard but for a contact machine. The pilot and observer of another bus saw two tanks converging eastward at either end of a troublesome Boche trench. A German officer, peering round a corner, drew back quickly when he found one of the new steel beasts advancing. He hurried to an observation post round a bend in the lines. Arrived there, he got the shock of his life when he found a second metal monster waddling towards him. Alarmed and unnerved, he probably ordered a retirement, for the trench was evacuated immediately. The observer in a watching aeroplane then delivered a much-condensed synopsis of the comedy to battalion headquarters, and the trench was peacefully occupied.

Inevitably the nearness of the enemy to machines hovering over a given area bred in the airmen concerned a desire to swoop down and panic the Boche. Movement in a hostile trench was irresistible, and many a pilot shot off his engine, glided across the lines, and let his observer spray with bullets the home of the Hun. The introduction of such tactics was not planned beforehand and carried out to order. It was the outcome of a new set of circumstances and almost unconscious enterprise. More than any other aspect of war flying, it is, I believe, this imminence of the unusual that makes the average war pilot swear greatly by his job, while other soldiers temper their good work with grousing. His actions are influenced by the knowledge that somewhere, behind a ridge of clouds, in the nothingness of space, on the patchwork ground, the True Romance has hidden a new experience, which can only be found by the venturer with alert vision, a quick brain, and a fine instinct for opportunity.

The free-lance ground stunt, then, had its origin in the initiative of a few pilots who recognised a chance, took it, and thus opened yet another branch in the huge departmental store of aerial tactics. The exploits of these pioneers were sealed with the stamp of official approval, and airmen on contact patrol have since been encouraged to relieve boredom by joyous pounces on Brother Boche.

The star turn last year was performed by a British machine that captured a trench. The pilot guided it above the said trench for some hundred yards, while the observer emptied drum after drum of ammunition at the crouching Germans. A headlong scramble was followed by the appearance of an irregular line of white billowings. The enemy were waving handkerchiefs and strips of material in token of surrender! Whereupon our infantry were signalled to take possession, which they did. Don't shrug your shoulders, friend the reader, and say: "Quite a good story, but tall, very tall." The facts were related in the R.F.C. section of 'Comic Cuts,' otherwise G.H.Q. summary of work.

Fighting squadrons soon caught the craze for ground stunts and carried it well beyond the lines. One machine chased a train for miles a few hundred feet above, derailed it, and spat bullets at the lame coaches until driven off by enemy craft. Another made what was evidently an inspection of troops by some Boche Olympian look like the riotous disorder of a Futurist painting. A pilot with some bombs to spare spiralled down over a train, dropped the first bomb on the engine, and the second, third, fourth, and fifth on the soldiers who scurried from the carriages. When a detachment of cavalry really did break through for once in a while, it was startled to find an aerial vanguard. A frolicsome biplane darted ahead, pointed out positions worthy of attack, and created a diversion with Lewis gun fire.

At the end of a three-hour offensive patrol my pilot would often descend our bus to less than a thousand feet, cross No Man's Land again, and zigzag over the enemy trenches, where we disposed of surplus ammunition to good purpose. On cloudy days, with the pretext of testing a new machine or a gun, he would fly just above the clouds, until we were east of the lines, then turn round and dive suddenly through the cloud-screen in the direction of the Boche positions, firing his front gun as we dropped. The turn of my rear gun came afterwards when the pilot flattened out and steered northward along the wrong border of No Man's Land. Once, when flying very low, we looked into a wide trench and saw a group of tiny figures make confused attempts to take cover, tumbling over each other the while in ludicrous confusion.

I remember a notable first trip across the lines made by a pilot who had just arrived from England. He had been sent up to have a look at the battle line, with an old-hand observer and instructions not to cross the trenches. However, he went too far east, and found himself ringed by Archie bursts. These did not have their customary effect on a novice of inspiring mortal funk, for the new pilot became furiously angry and flew Berserk. He dived towards Bapaume, dropped unscathed through the barrage of anti-aircraft shelling for which this stronghold was at the time notorious, fired a hundred rounds into the town square from a height of 800 feet, and raced back over the Bapaume-PoziÈres road pursued by flaming "onion" rockets. The observer recovered from his surprise in time to loose off a drum of ammunition at Bapaume, and three more along the straight road to the front line, paying special attention to the village of Le Sars.

It was above this village that I once was guilty of communicating with the enemy. During a three-hours' offensive patrol around the triangle—Bapaume-Mossy-Face Wood-Epehy—we had not seen a single Hun machine. Low clouds held Archie in check, and there was therefore small necessity to swerve from a straight course. Becoming bored, I looked at the pleasant-seeming countryside below, and reflected how ill its appearance harmonised with its merits as a dwelling-place, judged on the best possible evidence—the half-hysterical diaries found on enemy prisoners, the bitter outpourings anent the misery of intense bombardment and slaughter, the ominous title "The Grave" given to the region by Germans who had fought there. An echo of light-hearted incursions into German literature when I was a student at a Boche college suggested that the opening lines of Schiller's "Sehnsucht" were peculiarly apposite to the state of mind of the Huns who dwelt by the Somme. Wishing to share my discovery, I wrote the verse in large block capitals, ready to be dropped at a convenient spot. I took the liberty of transposing three pronouns from the first person to the second, so as to apostrophise our Boche brethren. The patrol finished, my pilot spiralled down to within a 300-yard range of the ground and flew along the road past Martinpuich, while I pumped lead at anything that might be a communication trench. We sprinkled Le Sars with bullets, and there I threw overboard the quotation from a great German poet, folded inside an empty Very's cartridge to which I had attached canvas streamers. If it was picked up, I trust the following lines were not regarded merely as wordy frightfulness:

Of all the tabloid tales published last year in R.P.C. 'Comic Cuts,' the most comic was that of a mist, a British bus, and a Boche General. The mist was troublesome; the bus, homeward bound after a reconnaissance, was flying low to keep a clear vision of the earth; the general was seated in his dignified car, after the manner of generals. The British pilot dived on the car, the British observer fired on the car, the Boche chauffeur stopped the car, the Boche general jumped from the car. Chauffeur and general rushed through a field into a wood; pilot and observer went home and laughed.

Thus far the facts are taken from the official report. An appropriate supplement was the rumour, which deserved to be true but possibly wasn't, that the observer turned in the direction of the vanished general and plagiarised George Robey with a shout into the unhearing air: "Cheeriho old thing, here's a go, my hat, priceless!"So much for past accomplishment. The future of war flying, like all futures, is problematical; but having regard to our present unquestionable superiority in the air, and to the blend of sane imagination and practical ability now noticeable as an asset of the flying services directorate, one can hazard the statement that in the extended aerial war which is coming the R.F.C. and R.N.A.S. will nearly satisfy the most exacting of critics.

The tendency is toward a rapid development of aircraft even more startling than that of the past. Some of the modern scout machines have a level speed of 130-150 miles an hour, and can climb more than 1000 feet a minute until an abnormal height is reached. It is certain that within a year later machines will travel 160, 180, and 200 miles an hour level. Quantity as well as quality is on the up-grade, so that the power to strike hard and far will increase enormously, helped by heavier armament, highly destructive bombs, and more accurate bomb-sights.

And, above all, we shall see a great extension of ground attacks by air cavalry. The production of a machine specially adapted for this purpose, armoured underneath, perhaps, and carrying guns that fire downward through the fuselage, is worth the careful attention of aeroplane designers. It is probable that with the reappearance of extended military movement on the western front, as must happen sooner or later, continuous guerilla tactics by hundreds of low-flying aeroplanes may well turn an orderly retirement into a disorderly rout.

When and if a push of pushes really breaks the German line, I fully expect that we of the air service will lead the armies of pursuit and make ourselves a pluperfect nuisance to the armies of retreat. Temporary second lieutenants may yet be given the chance to drive a Boche general or two into the woods, or even—who can limit the freaks of Providence?—plug down shots at the Limelight Kaiser himself, as he tours behind the front in his favourite rÔle of Bombastes Furioso.