On leaving the ground the aeroplanes fly dead into the wind for a couple of miles, circle back to the left around the aerodrome, and head into the wind again until the height at which the flight is to be carried out is reached. The first aeroplane to reach this height passes directly over the aerodrome and then steers a course to the first lighthouse. A comparison of this course with the previously figured course, and a comparison of the previously calculated ground speed with the time taken to travel from the aerodrome to the lighthouse enables the aviators, by the use of instruments and a few simple calculations, to gauge their drift. This process is continued on another course to the next lighthouse and the previously tested direction and velocity of wind are accurately checked in this way and future courses altered accordingly. These calculations are all important to the long-distance night bomber, for although roads show up in the moonlight like white threads, they are too numerous and interwoven to be followed for great distances, and although rivers and lakes look like silver ribbons and blotches, the moon may be obscured at any moment or the ground itself may be obliterated by low clouds or mist. Accuracy in aerial navigation, therefore, is of the utmost importance in long-distance night flying.
The night aviator, however, has many things to think of besides a constant checking and readjustment of his course according to variations in direction and velocity of wind. On his own side of the lines he is constantly challenged by searchlights which must be answered immediately if the aviator wishes to avoid the risk of being shot down by his own anti-aircraft guns or of being attacked by his own night-patrol machines. The method of answering these challenges is extremely simple. All that is required of the aviator is to shoot at the searchlight with a large pistol loaded with an enormous cartridge. The aviator, intent on his calculations and annoyed by any interruption, often wishes that this pistol was a deadly weapon, but it is not. It merely fires a certain colored light which floats slowly down changing in its descent to certain other colors, which prove to the officer in charge of the challenging searchlight that an Allied aeroplane is above him. The colors which are shown on one night, however, will not do on another, for these "colors of the day," as they are inappropriately called, are changed every night and the utmost secrecy is maintained in regard to them. Even the aviators do not know the "color of the day" until ten minutes before the start of a raid, neither do the officers in charge of the anti-aircraft batteries. The reason for this secrecy became apparent to the Bedouins one night when a Hun flew over our aerodrome shooting down our "color of the day," blinking his navigation lights, and finally firing down a red light which was our prearranged forced-landing signal. The aerodrome officer, believing that one of the Bedouin machines was returning from that night's raid with engine trouble, lit up the "landing T" and brought upon himself a shower of bombs which carried him into the Unknown.
After crossing the lines the aviators are intent on steering an accurate compass course, checking their position from time to time by various landmarks such as canals, rivers, cross-roads, and woods, and figuring changes in wind. The bursting shells of the enemy anti-aircraft batteries must be disregarded, for a slight détour around a particularly heavy barrage might mean an error of several degrees in their course which, unless corrected, would bring them twenty to thirty miles away from their objective after a flight of one hundred and seventy miles or more, and an accurate correction of a compass course after a wide détour is always difficult and sometimes impossible. Therefore, it is of the utmost importance for long-distance night bombers to hold their course regardless of the enemy's efforts at destruction.
The hatred in the hearts of the Huns, expressed by the constant "whonk" of bursting anti-aircraft shells, contrasts disagreeably with the loveliness of the moonlit panorama. All man's disfigurements of the earth are obliterated by distance and nothing but a scene of inspiring beauty is in view from the aviaors' lofty outlook at a height of several thousand feet.
The flashings of the guns, the "flaming onions,"—i.e., strings of phosphorus balls shot up to light the sky and to ignite any inflammable substance with which they come in contact,—and the black puffs of smoke from the bursting shells add a weird and startling brilliancy to the surroundings. No matter how many times a man may fly at night the immensity of the heavens above him, crowded with unknown worlds, cannot fail to impress him with his own insignificance in the general scheme of the universe, and Death itself appears of small importance compared to the way in which he faces it.
The aviators, however, have little time for reflection, for on a long flight they must keep a constant outlook for such landmarks as will enable them from time to time to mark their exact position on the chart and by comparison with their compass course and "ground speed" vary their course according to changes in direction and velocity of wind. An instrument called the "pitot tube" indicates the speed at which the aeroplane passes through the air, but the speed at which the plane travels in relation to the ground depends on the direction and velocity of the wind. They must also watch the flashes from anti-aircraft batteries and pin-point them on their maps if possible; aerodromes which are lit up, train movements, the lighting of towns, the blaze of steel factories; in fact everything of military importance must be recorded and reported upon, if accurately located. The night aviator, however, must be extremely careful in his observations, for it is very easy to get lost and it is extremely difficult to keep an accurate check, on the charts, of your exact position over the ground, even after long practice; especially is this true when the flight covers three to four hundred miles in distance and lasts from eight to nine hours.
After several hours of intense concentration the aviators approach their target, and although they have charted the course constantly they now spend some time in flying back and forth while they check off on a large-scale map the landmarks about the target and satisfy themselves that their long flight will not be valueless if the bombs are dropped with accuracy. In the meantime the sound of the motors, together with the telegraphed intelligence from other Hun towns, tells the enemy that Allied night bombers are in the vicinity. The Huns in charge of the anti-aircraft defences stationed about the target direct huge beams of numerous searchlights toward the sky and an intense barrage is put up above and around the target by the Hun batteries. The air is filled with shrapnel from bursting shells at the altitude at which the machine is flying, for the Huns have accurate instruments which gauge the altitude of an aeroplane from the sound vibrations of its engines. The aviators, however, are still intent on picking out their target (probably a factory which manufactures war material) and have not yet entered the barrage. The Huns, I imagine, often wondered why British bombers flew about a town for such a long time before bombing; the inhabitants always had more than enough time to enter the dug-outs before the bombs dropped. The British bombers, however, were not making war on women and children; they were intent on destroying a poisonous gas factory or other targets of military importance; so they flew about the town until the target was accurately located; then and not till then, they throttled down their engines and glided swiftly down between the searchlight beams and below the barrage of bursting shells, for once the engines are throttled down the enemy's sound instruments are valueless and the anti-aircraft barrage ranged at the previous altitude of the aeroplane fills the air with shrapnel far above the rapidly descending plane. A quick adjustment of bomb-sights to compensate for the altitude, speed, and drift of the plane and the front fore-sight soon is in line with the target, and after a pause the back fore-sight coming in line with the back-sight gives, with the previously adjusted stop-watch, the exact moment for releasing the first bombs. The plane passes over the target and turns on a steep "bank," while the aviators watch for the burst of the bombs. The bomb-sight is readjusted to the reduced altitude, another sight taken, the remainder of the bombs released, and then, nose down, engine "full out," the huge plane rushes through the lowered barrage for more congenial surroundings.
Great care must be taken when bombing a factory, for usually very close to it the Hun has located an unprotected prison camp filled with Allied prisoners, and we have official information that prisoners have so infuriated the Hun guards by singing "God save the King" or the "Marseillaise" during a bombardment of the near-by factory that they have been bayoneted to punish them for their "insolence." As soon as the aviators are away from the barrage, they steer a straight course for home, and again an intent outlook is kept for landmarks which will enable them to mark their position on the charts and figure their ground speed and drift. If their course is correct, they will see after a few hours a lighthouse several miles away dimly flashing a letter in Morse code. They head straight for this, and when over it they steer a course which will bring them to the lighthouse situated near their aerodrome. As they approach the aerodrome they fire down the "color of the day" and if the aerodrome is not under bombardment by the Huns the flare-path is lighted and the pilot spirals slowly down while the allotted letter of the plane is being flashed in Morse code on its navigation lights; as soon as this signal is answered from the ground, the pilot glides swiftly down to the flare-path. When fifteen to ten feet from the ground the Holt's flares attached to the wing tips of the planes are lit by electrical contact and the landing is made in a momentary but brilliant blaze of light.
It is interesting to sit in the officers' mess of a night-bombing squadron and watch the returning aviators enter. They are cold and stiff and all are very tired, for no man can fly without fatigue from dusk to dawn under conditions which demand intense concentration and entail a considerable amount of nervous strain, but now is shown the difference in temperament; some return with bloodshot eyes and haggard faces which indicate a condition of intense fatigue; others come in gaily as though home from a late dance; still others thoughtfully quiet. All of them, however, show signs of nervous strain and mental tension and they must relax their taut nerves before going to bed, especially if the raid was but another similar to those that had been carried out on several previous nights. So, while relaxing they eat bully beef sandwiches and drink hot chocolate or beer or, if the night has been particularly cold, a glass of hot rum. Deafened by the roar of the engines and the sudden change in atmospheric pressure they either whisper or yell if they speak at all, during the first few minutes after entering the mess. But the raid is over, so very little is said about it; every now and then some one looks at his watch and sees that nine hours have elapsed since the raid started; he says nothing but he and all realize that the machine which has not returned has used up its supply of petrol and that the fate of a dear friend will remain unknown perhaps for weeks, perhaps for all time.