The position in the sky between two such combatants is closely a.n.a.logous to that of a torpedo boat and a Dreadnought. The latter, so long as it can keep the former at arm's, or rather gun's, distance is perfectly safe. The torpedo boat can only aspire to hara.s.s its enemy by buzzing around, hoping that a lucky opportunity will develop to enable it to rush in and to launch its torpedo. It is the same with the aeroplane when arrayed against a Zeppelin. It is the mosquito craft of the air.

How then can a heavier-than-air machine triumph over the unwieldy lighter-than-air antagonist? Two solutions are available. If it can get above the dirigible the adroplane may bring about the dirigible's destruction by the successful launch of a bomb. The detonation of the latter would fire the hydrogen within the gas-bag or bags, in which event the airship would fall to earth a tangled wreck. Even if the airship were inflated with a non-inflammable gas--the Germans claim that their Zeppelins now are so inflated--the damage wrought by the bomb would be so severe as to destroy the airship's buoyancy, and it would be forced to the ground.

The alternative is very much more desperate. It involves ramming the dirigible. This is undoubtedly possible owing to the speed and facile control of the aeroplane, but whether the operation would be successful remains to be proved. The aeroplane would be faced with such a concentrated hostile fire as to menace its own existence--its forward rush would be frustrated by the dirigible just as a naval vessel parries the ramming tactics of an enemy by sinking the latter before she reaches her target, while if it did crash into the hull of the dirigible, tearing it to shreds, firing its gas, or destroying its equilibrium, both protagonists would perish in the fatal dive to earth. For this reason ramming in mid-air is not likely to be essayed except when the situation is desperate.

What happens when two aeroplanes meet in dire combat in mid-air and one is vanquished? Does the unfortunate vessel drop to earth like a stone, or does it descend steadily and reach the ground uninjured? So far as actual experience has proved, either one of the foregoing contingencies may happen. In one such duel the German aeroplane was observed to start suddenly upon a vol-plane to the ground. Its descending flight carried it beyond the lines of the Allies into the territory of its friends.

Both came to the conclusion that the aviator had effected his escape.

But subsequent investigation revealed the fact that a lucky bullet from the Allies' aeroplane had lodged in the brain of the German pilot, killing him instantly. At the moment when Death over took him the aviator had set his plane for the descent to the ground, and the machine came to earth in the manner of a glider.

But in other instances the descent has been far more tragic. The aeroplane, deprived of its motive power, has taken the deadly headlong dive to earth. It has struck the ground with terrific violence, burying its nose in the soil, showing incidentally that a flying machine is an indifferent plough, and has shattered itself, the debris soaked with the escaping fuel becoming ignited. In any event, after such a fall the machine is certain to be a wreck. The motor may escape damage, in which event it is salvaged, the machine subsequently being purposely sacrificed to the flames, thereby rendering it no longer available to the enemy even if captured. In many instances the hostile fire has smashed some of the stays and wires, causing the aeroplane to lose its equilibrium, and sending it to earth in the manner of the proverbial stone, the aviators either being dashed to pieces or burned to death.

What are the vulnerable parts of the aeroplane? While the deliberate intention of either combatant is to put his antagonist hors de combat, the disablement of the machine may be achieved without necessarily killing or even seriously wounding the hostile airman. The prevailing type of aeroplane is highly susceptible to derangement: it is like a ship without armour plate protection. The objective of the antagonist is the motor or the fuel-tank, the vital parts of the machine, as much as the aviator seated within.

A well-planted shot, which upsets the mechanism of the engine, or a missile which perforates the fuel tank, thereby depriving the motor of its sustenance, will ensure victory as conclusively as the death of the aviator himself. Rifle fire can achieve either of these ends with little difficulty. Apart from these two nerve-centres, bombardment is not likely to effect the desired disablement, inasmuch as it cannot be rendered completely effective. The wings may be riddled like a sieve, but the equilibrium of the machine is not seriously imperilled thereby.

Even many of the stays may be shot away, but bearing in mind the slender objective they offer, their destruction is likely to be due more to luck than judgment. On the other hand, the motor and fuel tank of the conventional machine offer attractive targets: both may be put out of action readily, and the disablement of the motive power of an enemy's craft, be it torpedo-boat, battleship, or aeroplane, immediately places the same at the a.s.sailant's mercy.

Nevertheless, of course, the disablement of the airman brings about the desired end very effectively. It deprives the driving force of its controlling hand; The aeroplane becomes like a ship without a rudder: a vessel whose helmsman has been shot down. It is unmanageable, and likely to become the sport of the element in which it moves. It is for this reason that aviators have been urged to direct their fire upon the men and mechanism of a dirigible in the effort to put it out of action.

An uncontrolled airship is more likely to meet with its doom than an aeroplane. The latter will inevitably glide to earth, possibly damaging itself seriously in the process, as events in the war have demonstrated, but a helpless airship at once becomes the sport of the wind, and anyone who has a.s.sisted, like myself, in the descent of a vessel charged with gas and floating in the air, can appreciate the difficulties experienced in landing. An uncontrolled Zeppelin, for instance, would inevitably pile up in a tangled twisted ruin if forced to descend in the manner of an ordinary balloon. Consequently the pilot of a dirigible realises to the full the imperative urgency of keeping beyond the point-blank fire of aerial mosquito craft.

The a.s.siduity with which British aviators are prepared to swarm to the attack has been responsible for a display of commendable ingenuity on the part of the German airman. Nature has provided some of its creatures, such as the octopus, for instance, with the ways and means of baffling its pursuers. It emits dense clouds of inky fluid when disturbed, and is able to effect its escape under cover of this screen.

The German aviator has emulated the octopus. He carries not only explosive bombs but smoke b.a.l.l.s as well. When he is pursued and he finds himself in danger of being overtaken, the Teuton aviator ignites these missiles and throws them overboard. The aeroplane becomes enveloped in a cloud of thick impenetrable smoke. It is useless to fire haphazard at the cloud, inasmuch as it does not necessarily cover the aviator. He probably has dashed out of the cloud in such a way as to put the screen between himself and his pursuer.

In such tactics he has merely profited by a method which is practised freely upon the water. The torpedo boat flotilla when in danger of being overwhelmed by superior forces will throw off copious clouds of smoke.

Under this cover it is able to steal away, trusting to the speed of the craft to carry them well beyond gunshot. The "smoke screen," as it is called, is an accepted and extensively practised ruse in naval strategy, and is now adopted by its mosquito colleagues of the air.

CHAPTER XIII. TRICKS AND RUSES TO BAFFLE THE AIRMAN

The airman has not been allowed to hold his undisputed sway in military operations for long. Desperate situations demand drastic remedies and already considerable and illuminating ingenuity is being displayed to baffle and mislead the scout of the skies.

It is a somewhat curious and noteworthy fact, that the Germans were among the first to realise the scope of the airman's activities, and the significance of their relation to the conveyance of intimate information and the direction of artillery fire. Consequently, they now spare no effort to convey illusory information, in the hope that the hostile force may ultimately make a false move which may culminate in disaster.

Thus, for instance, as much endeavour is bestowed upon the fashioning of dummy trenches as upon the preparation of the actual lines of defence.

And every care will be taken to indicate that the former are strongly held. The dug-outs are complete and at places are apparently cunningly masked. If the airman is flying swiftly, he is likely to fail to distinguish the dummy from the real trenches. To him the defences appear to be far more elaborate and more strongly held than is the actual case.

The advantage of this delusion is obvious when a retreat is being made.

It enables the enemy to withdraw his forces deliberately and in perfect order, and to a.s.sume another and stronger position comparatively at leisure. The difficulty of detecting the dummies is emphasised, inasmuch as now, whenever the sound of an aeroplane is heard, or a glimpse thereof is obtained, the men keep well down and out of sight. Not a sign of movement is observable. For all the airman may know to the contrary, the trenches may be completely empty, whereas, as a matter of fact, they are throbbing with alert infantry, anxious for a struggle with the enemy.

This is one instance where the dirigible is superior to the aeroplane.

The latter can only keep circling round and round over the suspicious position; the movement through the air interferes with close continuous observation. On the other hand, the dirigible can maintain a stationary position aloft for hours on end. Then the issue is resolved into a contest of patience, with the advantage to the airman. The soldiers in the trenches fret and fume under cover; confined concealment is irksome and is a supreme test of the nerves. Unless the soldiers are made of very stern stuff, physical endurance succ.u.mbs. Some rash act--apparently very trivial--may be committed; it suffices for the vigilant sentinel overhead. He detects the slender sign of life, forms his own conclusions, and returns to his headquarters with the intelligence that the enemy is playing "Brer Rabbit."

It has also become increasingly difficult for the airman to gather absolutely trustworthy data concerning the disposition and movement of troops. Small columns are now strung out along the highways to convey the impression that the moving troops are in far greater force than is actually the case, while the main body is under the cover offered by a friendly wood and is safe from detection. The rapidity with which thousands of men are able to disappear when the word "Airman" is pa.s.sed round is astonishing. They vanish as completely and suddenly as if swallowed by the earth or dissolved into thin air. They conceal themselves under bushes, in ditches, lie p.r.o.ne under hedgerows, dart into houses and outbuildings--in short, take every cover which is available, no matter how slender it may seem, with baffling alacrity. The attenuated column, however, is kept moving along the highway for the express purpose of deceiving the airman.

Advancing troops also are now urged to move forward under the shelter of trees, even if the task entails marching in single or double file, to escape the prying eyes of the man above. By keeping close to the line of trunks, thus taking full advantage of the overhanging branches, and marching in such a manner as to create little dust, it is possible to escape the aerial scout.

The concealment of cavalry, however, is somewhat difficult. An animal, especially if he be unaccustomed to the noise of the aeroplane, is likely to become startled, and to give vent to a frightened and vociferous neighing which invariably provokes a hearty response from his equine comrades. The sharp ear of the airman does not fail to distinguish this sound above the music of his motor. Again, he has come to regard all copses and stretches of undergrowth with suspicion. Such may or may not harbour the enemy, but there is no risk in making an investigation. He swoops down, and when a short distance above the apparently innocent copse, circles round it two or three times. Still undecided, he finally hurls a bomb. Its detonation invariably proves effective. The horses stampede and the secret is out. Even foot soldiers must be severely trained and experienced to resist the natural inclination to break cover when such a missile is hurled into their midst.

Frequently a force, which has laboured under the impression that it is safe from detection, has revealed its presence unwittingly and upon the spur of the moment. If the men be steeled against the bomb attack, it is almost impossible to resist the inclination to take a shot when the airman, swooping down, ventures so temptingly near as to render him an enticing target almost impossible to miss. As a rule, however, the observer is on the alert for such a betrayal of a force's existence.

When the bomb fails to scatter the enemy, or the men are proof against the temptation to fire a volley, a few rounds from the aeroplane's machine gun often proves effective. If the copse indeed be empty no harm is done, beyond the abortive expenditure of a few rounds of ammunition: if it be occupied, the fruits of the manoeuvre are attractive. Cunning is matched against cunning, and the struggle for supremacy in the art of craftiness is keen.

The French Flying Corps have had recourse to an ingenious ruse for accomplishing two ends--the one to draw concealed artillery fire, and the other to pre-occupy the airmen. Two German aerial scouts observed a French machine flying at a somewhat venturesome height over their masked artillery. Divining the reason for the hostile intrepidity they gave chase. Circling round the French machine they a.s.sailed it with machine-gun fire. The enemy appeared to take no notice but continued his gradual descent in a steady line.

Presently the German airmen, having drawn sufficiently near, observed that the French aviator was inert. Had he been killed? Everything pointed to such a conclusion, especially as they had raked the aeroplane fore and aft with bullets. But still suspicious they continued their circling movements, their attention so concentrated upon their quarry that they had not observed another move. It was the crash of guns from their masked artillery which broke in upon their absorption. Looking round, they observed three French aeroplanes soaring around and above them at high speed. Scarcely had they realised the situation before a spirited mitraireuse fire was rained upon them. One of the German aeroplanes was speedily disabled. Its fuel tank was riddled and it sank rapidly, finally crashing to earth in the deadly dive head foremost, and killing both its occupants in the fall. The second aeroplane hurried away with its pilot wounded. In the excitement of the aerial melee the first French aeroplane had been forgotten. It was now scarcely 100 feet above the German artillery. A capture appeared to be imminent, but the Germans received a rude surprise. Suddenly the aeroplane exploded and a hail of shrapnel burst over the heads of the artillerymen.

The circ.u.mstance was decidedly uncanny, but after two or three such experiences of exploding aeroplanes the matter was explained. The apparently helpless aeroplane was merely a glider, which, instead of carrying a man, had a b.o.o.by-trap aboard.

It appears that the French airmen have found a use for the aeroplanes which are considered unsafe for further use. The motor and propeller are removed and the dummy of explosives is strapped into position. The laden glider is then taken aloft by means of an airship, and in the concealment of the clouds is released, the rudder being so set as to ensure a gradual vol-plane towards the suspicious position below. The explosive cargo is set with a time fuse, the arrangement being that the contents will be detonated while the machine is near the ground, unless this end is accelerated by a well-planted sh.e.l.l from an anti-aircraft gun. The decoy glider is generally accompanied by one or two aeroplanes under control, which keep under the cover of the clouds until the hostile aviators have been drawn into the air, when they swoop down to the attack. The raiders are fully aware that they are not likely to become the target of fire from the ground, owing to the fact that the enemy's artillery might hit its friends. Consequently the antagonistic airmen are left to settle their own account. In the meantime the dummy machine draws nearer to the ground to explode and to scatter its death-dealing fragments of steel, iron, and bullets in all directions.

Possibly in no other phase of warfare is subterfuge practised so extensively as in the concealment of guns. The branches of trees const.i.tute the most complete protection and guns are placed in position beneath a liberal cover of this character. The branches also offer a screen for the artillerymen, who can lurk beneath this shelter until the aeroplane has pa.s.sed. To complete the illusion dummy guns fashioned from tree trunks and the wheels of useless limbers are rigged up, and partially hidden under branches, the idea being to convey the impression to the man aloft that they are the actual artillery.

The aerial scout observes the dummies beneath the spa.r.s.e covering of branches. Congratulating himself upon his sharp eyesight, he returns to his base with the intelligence that he has found the enemy's guns he indicates their position upon the map, and in some cases returns to notify the position of the weapons by smoke-ball or tinsel, when they are immediately subjected to a severe bombardment. He follows the sh.e.l.l-fire and sees the arms put out of action. He returns to camp satisfied with his exploit, oblivious of the smiles and laughter of the hostile artillerymen, who have their guns safely in position and well masked some distance away. The dummies are imperfectly concealed purposely, so that they may be discovered by the aerial scout, while the real guns are completely masked and ready to belch forth from another point. In one or two cases the dummies have been rigged up in such a manner as to convey the impression, when seen from aloft, that a whole battery has been put out of action, barrels and wheels as well as broken limbers strewing the ground in all directions.

Moving ma.s.ses of soldiers are also resorting to cunning in order to mislead the airman or to escape his observation. At the battle of Haelen, during which engagement the German warplanes were exceptionally active, the Belgian soldiers covered their heads with bundles of wheat s.n.a.t.c.hed from the standing stooks, and under this cover lurked in a field where the corn was still standing. From aloft their forms defied detection: the improvised headgear completely covered them and blended effectively with the surrounding wheat. In another instance the French misled a German airman somewhat effectively. What appeared to be cavalry was seen to be retreating along the country road, and the airman returned hurriedly to report. A German squadron was dispatched in hasty pursuit. But as it rounded a copse skirting the road it received a murderous fire at close quarters, which decimated the ranks and sent the survivors flying for their lives along the road up which they had ridden so confidently. Had the aviator been in a position to observe the horses more closely, he would have found that what appeared to be riders on their backs were in reality sacks stuffed with straw, dressed in old uniforms, and that a mere handful of men were driving the animals forward. The cavalrymen had purposely dismounted and secreted themselves in the wood in antic.i.p.ation of such a pursuit as was made.

While the Germans do not appear to be so enterprising in this form of ingenuity they have not been idle. A French airman flying over the Teuton lines observed the outermost trenches to be alive with men whose helmets were distinctly visible. The airman reported his observations and the trench was subjected to terrific sh.e.l.l fire. Subsequently the French made a spirited charge, but to their dismay found that the outermost German trench was occupied by dummies fashioned from all sorts of materials and crowned with helmets! This ruse had enabled the German lines to be withdrawn to another position in safety and comparatively at leisure.

Before war was declared the German military experts were emphasising the importance of trees for masking troops and guns against aerial observation. One of the foremost authorities upon military aviation only a few months ago urged the German Military Staff to encourage the planting of orchards, not for the purpose of benefiting agriculture or in the interests of the farmers, but merely for military exigencies.

He pointed to the extensive orchards which exist in Alsace-Lorraine and Baden, the military covering value of which he had determined from personal experience, having conducted aerial operations while military were moving to and fro under the cover of the trees. He declared that the cover was efficient and that under the circ.u.mstances the laying out of extensive orchards in strategical places should be carried out without any delay. This, he urged, was a national and not a private obligation. He advocated the bestowal of subsidies on the farmers to encourage the planting of fruit trees. He suggested that the trees should be provided by the State, and given to all who were prepared to plant them; that substantial prizes should be awarded to encourage the rapid growth thereof, and that annual prizes should be awarded to the man who would undertake their cultivation and pruning, not from the fruit-yielding point of view, but for facilitating the movement of troops beneath their dense branches.

He even urged the military acquisition of suitable land and its determined, skilful, and discreet exploitation by those who loved the Fatherland. He emphasised the necessity for keeping such orchards under military control, only vouchsafing sufficient powers to the local authorities to ensure the desired consummation. He maintained that, if the work were prosecuted upon the right lines and sufficient financial a.s.sistance were given, the purpose in view could be achieved without saddling the war department with any unremunerative or excessive burden.

He admitted that the process of raising fruit trees to the stage when they would afford adequate cover would be tedious and somewhat prolonged, but argued that the military advantages, such as enabling troops to move below the welcome shelter with absolute freedom and without physical fatigue, would be an ample compensation.

The utility of such cover to artillery was another factor he did not fail to emphasise. He dwelt seriously upon the difficulty of rendering permanent gun emplacements and heavy artillery invisible to the airman by resort to the usual type of gun shields. The latter may be located with ease by alert airmen, whereas if the guns were under cover of fruit trees they would be able to accomplish their deadly mission without betraying their presence to the aerial scout. Moreover, by pruning the trees in such a manner as to ensure free movement beneath, the artillery would be able to advance without betraying the fact to the enemy.

This authority vigorously insisted that the work should be carried out without a moment's delay as it was vital to the Fatherland. In the light of recent events, and the excellent cover which is offered by the orchards of the territory he cited as an ill.u.s.tration of his contention, such a disclosure is pregnant with meaning. It throws a new light upon the thorough methods with which the Germans carried out their military preparations, and incidentally shows that they were fully alive to every possible development. Fruit-raising as a complement to military operations may be a new line of discussion, but it serves to reveal the German in his true light, ready for every contingency, and shows how thoroughly he appreciates the danger from the man in the clouds.

CHAPTER XIV. ANTI-AIRCRAFT GUNS. MOBILE WEAPONS.

When the airship and the aeroplane became accepted units of warfare it was only natural that efforts should be concentrated upon the evolution of ways and means to compa.s.s their destruction or, at least, to restrict their field of activity. But aircraft appeared to have an immense advantage in combat. They possess virtually unlimited s.p.a.ce in which to manoeuvre, and are able to select the elevation from which to hurl their missiles of destruction.

There is another and even more important factor in their favour. A projectile fired, or even dropped, from a height, say of 5,000 feet, is favourably affected by the force of gravity, with the result that it travels towards the earth with acc.u.mulating energy and strikes the ground with decisive force.

On the other hand, a missile discharged into s.p.a.ce from a weapon on the earth has to combat this action of gravity, which exercises a powerful nullifying influence upon its flight and velocity, far in excess of the mere resistance offered by the air. In other words, whereas the projectile launched from aloft has the downward pull of the earth or gravitational force in its favour, the sh.e.l.l fired from the ground in the reverse direction has to contend against this downward pull and its decelerating effect.

At the time when aircraft entered the realms of warfare very little was known concerning the alt.i.tudes to which projectiles could be hurled deliberately. Certain conclusive information upon this point was available in connection with heavy howitzer fire, based on calculations of the respective angles at which the projectile rose into the air and fell to the ground, and of the time the missile took to complete its flight from the gun to the objective. But howitzer fire against aircraft was a sheer impossibility: it was like using a six-inch gun to kill a fly on a window pane at a thousand yards' range. Some years ago certain experiments in aerial firing with a rifle were undertaken in Switzerland. The weapon was set vertically muzzle upwards and discharged. From the time which elapsed between the issue of the bullet from the muzzle until it struck the earth it was possible to make certain deductions, from which it was estimated that the bullet reached an alt.i.tude of 600 feet or so. But this was merely conjecture.

Consequently when artillerists entered upon the study of fighting air-craft with small arms and light guns, they were compelled to struggle in the dark to a very p.r.o.nounced extent, and this darkness was never satisfactorily dispelled until the present war, for the simple reason that there were no means of getting conclusive information. The German armament manufacturers endeavoured to solve the problem by using smoking sh.e.l.ls or missiles fitted with what are known as tracers. By following the ascensional path of the projectiles as revealed by the smoke it was possible to draw certain conclusions. But these were by no means convincing or illuminating, as so many factors affected the issue.

Despite the peculiar and complex difficulties a.s.sociated with the problem it was attacked some what boldly. In this trying field of artillery research the prominent German armament manufacturers, Krupp of Essen and Ehrhardt of Dusseldorf, played a leading part, the result being that before the airship or the aeroplane was received within the military fold, the anti-aircraft gun had been brought into the field of applied science. The sudden levelling-up serves to ill.u.s.trate the enterprise of the Germans in this respect as well as their perspicacity in connection with the military value of aircraft.

Any gun we can hope to employ against aircraft with some degree of success must fulfil special conditions, for it has to deal with a difficult and elusive foe. Both the lighter-than-air and the heavier than-air craft possess distinctive features and varying degrees of mobility. Taking the first-named, the facility with which it can vary its alt.i.tude is a disconcerting factor, and is perplexing to the most skilful gunner, inasmuch as he is called upon to judge and change the range suddenly.

On the other hand, the artilleryman is favoured in certain directions.