For thirty hours the flight had "stood by" for a long reconnaissance. We were dragged from bed at 4.30 of dawn, only to return gratefully beneath the blankets three-quarters of an hour later, when a slight but steady rain washed away all chance of an immediate job. The drizzle continued until after sundown, and our only occupations throughout the day were to wade from mess to aerodrome, aerodrome to mess, and to overhaul in detail machines, maps, guns, and consciences.

Next morning again we dressed in the half-light, and again went back to bed in the daylight. This time the show had been postponed because of low clouds and a thick ground-mist that hung over the reeking earth. It was a depressing dawn—clammy, moist, and sticky.

But by early afternoon the mist had congealed, and the sheet of clouds was torn to rags by a strong south-west wind. The four craft detailed for the reconnaissance were therefore lined outside their shed, while their crews waited for flying orders. I was to be in the leading bus, for when C.'s death left vacant the command of A Flight, the good work of my pilot had brought him a flight-commandership, a three-pipped tunic, and a sense of responsibility which, to my relief, checked his tendency to over-recklessness. He now came from the squadron office with news of a changed course.

"To get the wind behind us," he explained, "we shall cross well to the south of PÉronne. Next, we go to Boislens. After that we pass by Nimporte, over the ForÊt de Charbon to SiÈgecourt; then up to Le Recul and back by Princebourg, St. Guillaume, and ToutprÈs.

"As regards the observers, don't forget to use your field-glasses on the rolling stock; don't forget the precise direction of trains and motor transport; don't forget the railways and roads on every side; don't forget the canals; and for the Lord's and everybody else's sake, don't be surprised by Hun aircraft. As regards the pilots—keep in close formation when possible; don't straggle and don't climb above the proper height."

The pilots ran their engines once more, and the observers exchanged information about items such as Hun aerodromes and the number of railway stations at each large town. An air reconnaissance is essentially the observer's show; its main object being to supply the "I" people at headquarters with private bulletins from the back of the German front. The collection of reconnaissance reports is work of a highly skilled nature, or ought to be. Spying out the land is much more than a search of railways, roads, and the terrain generally. The experienced observer must know the German area over which he works rather better than he knows Salisbury Plain. The approximate position of railway junctions and stations, aerodromes, factories, and depÔts should be familiar to him, so that he can without difficulty spot any new feature. Also he must be something of a sleuth, particularly when using smoke as a clue. In the early morning a thin layer of smoke above a wood may mean a bivouac. If it be but a few miles behind the lines, it can evidence heavy artillery. A narrow stream of smoke near a railway will make an observer scan the line closely for a stationary train, as the Boche engine-drivers usually try to avoid detection by shutting off steam. The Hun has many other dodges to avoid publicity. When Allied aircraft appear, motor and horse transport remain immobile at the roadside or under trees. Artillery and infantry are packed under cover; though, for that matter, the enemy very rarely move troops in the daytime, preferring the night or early morning, when there are no troublesome eyes in the air.

To foil these attempts at concealment is the business of the observers who gather information for Army Headquarters and G. H.Q. For observers on corps work the detective problems are somewhat different. This department deals with hidden saps and battery positions, and draws and photographs conclusions from clues such as a muzzle-blast, fresh tracks, or an artificial cluster of trees. All reconnaissance observers must carry out a simultaneous search of the earth for movement and the sky for foes, and in addition keep their guns ready for instant use. And should anything happen to their machines, and a forced landing seem likely, they must sit tight and carry on so long as there is the slightest hope of a safe return.

A nos moutons. I made a long list in my note-book of the places where something useful was likely to be observed, and tried my gun by firing a few shots into the ground. We hung around, impatient at the long delay.

"Get into your machines," called the Squadron Commander at last, when a telephone message had reported that the weather conditions toward the east were no longer unfavourable. We took to the air and set off.

V. led his covey beyond Albert and well south of the Somme before he turned to the left. Then, with the strong wind behind us, we raced north-east and crossed the strip of trenches. The pilot of the emergency machine, which had come thus far to join the party if one of the other four dropped out, waved his hand in farewell and left for home.

Archie barked at us immediately, but he caused small trouble, as most of his attention was already claimed by a party of French machines half a mile ahead. Anyhow we should have shaken him off quickly, for at this stage of the journey, with a forty-mile wind reinforcing our usual air speed of about ninety-five miles an hour, our ground speed was sufficient to avoid lingering in any region made unhealthy by A.-A. guns. The water-marked ribbon of trenches seemed altogether puny and absurd during the few seconds when it was within sight. The winding Somme was dull and dirty as the desolation of its surrounding basin. Some four thousand feet above the ground a few clouds moved restlessly at the bidding of the wind.

Passing a few small woods, we arrived without interruption over the railway junction of Boislens. With arms free of the machine to avoid unnecessary vibration, the observers trained their glasses on the station and estimated the amount of rolling stock. A close search of the railway arteries only revealed one train. I grabbed pencil and note-book and wrote: "Boislens, 3.5 P.M. 6 R.S., 1 train going S.W."

Just west of our old friend Mossy-Face were two rows of flagrantly new trenches. As this is one of the points where the enemy made a stand after their 1917 spring retreat, it can be assumed that even as far back as last October they were preparing new lines of defence, Hindenburg or otherwise. Not far west of these defence works were two troublesome aerodromes at Bertincourt and Velu, both of which places have since been captured.

A hunt for an aerodrome followed. V., who knew the neighbourhood well, having passed above it some two-score times, was quick to spot a group of hitherto unnoted sheds north of Boislens, towards Mossy-Face. He circled over them to let me plot the pin-point position on the map and sketch the aerodrome and its surroundings. The Hun pilots, with thoughts of a possible bomb-raid, began to take their machines into the air for safety.

"Got 'em all?" Thus V., shouting through the rubber speaking-tube, one end of which was fixed inside my flying-cap, so that it always rested against my ear.

"Correct. Get on with the good work."

The good work led us over a region for ever associated with British arms. Some of the towns brought bitter memories of that anxious August three years back. Thus Nimporte, which saw a desperate but successful stand on one flank of the contemptible little army to gain time for the main body; Ventregris, scene of a cavalry charge that was a glorious tragedy; LÀbas, where a battery of horse-gunners made for itself an imperishable name; SiÈgecourt, where the British might have retired into a trap but didn't; and Le Recul itself, whence they slipped away just in time.

In the station at Nimporte a train was waiting to move off, and two more were on their way to the military base of PlusprÈs. Both attempted to hide their heads by shutting off steam immediately the drone of our engines made itself heard; but we had spotted them from afar, and already they were noted for the information of Brass Hats.The next item of interest was activity at a factory outside a little town. Black trails of smoke stretched away from the chimneys; and surely, as we approached a minute ago, a short column of lorries was passing along a road towards the factory. Yet when we reached the spot there was no sign of road transport. Nevertheless, I was certain I had seen some motor vehicles, and I entered the fact in my note-book. Likewise I took care to locate the factory site on my map, in case it deserved the honour of a bomb attack later.

Our bus led the way across the huge unwieldy ForÊt de Charbon, patterned in rectangular fashion by intersecting roads, and we arrived at SiÈgecourt. This is at once a fortress and an industrial town. There are several railway stations around it, and these added greatly to the observers' collection of trains and trucks. The Huns below, with unpleasant memories of former visits from British aircraft, probably expected to be bombed. They threw up at us a large quantity of high-explosive shells, but the shots were all wide and we remained unworried. To judge by the quality of the A.-A. shooting each time I called there, it seemed likely that half-trained A.-A. gunners were allowed to cut their active service teeth on us at SiÈgecourt.

Having squeezed SiÈgecourt of all movement, we headed for Le Recul. Here the intricate patchwork of railway kept the observers busy, and six more trains were bagged. Then, as this was the farthest point east to be touched, we turned to the left and travelled homeward.

It was soon afterwards that our engine went dud. Instead of a rhythmic and continuous hum there was at regular intervals a break, caused by one of the cylinders missing explosion at each turn of the rotary engine. The rev.-counter showed that the number of revolutions per minute had fallen off appreciably. Decreased revs. meant less speed, and our only chance to keep with the others was to lose height continuously. We were then nearly fifty miles from the lines.

I noticed the gap in the engine's drone as soon as it began. An airman is accustomed to the full roar of his engine, and it never distracts his attention, any more than the noise of a waterfall distracts those who live near it. But if the roar becomes non-continuous and irregular he is acutely conscious of the sound.

When the machine began to lose height I knew there was a chronic miss. V. looked round and smiled reassuringly, though he himself was far from reassured. He tried an alteration in the carburettor mixture, but this did not remedy matters. Next, thinking that the engine might have been slightly choked, he cut off the petrol supply for a moment and put down the nose of the machine. The engine stopped, but picked up when the petrol was once more allowed to run. During the interval I thought the engine had ceased work altogether, and was about to stuff things into my pocket in readiness for a landing on hostile ground.

We continued in a westerly direction, with the one cylinder still cutting out. To make matters worse, the strong wind that had been our friend on the outward journey was now an enemy, for it was drifting us to the north, so that we were obliged to steer almost dead into it to follow the set course.

As we passed along the straight canal from Le Recul to Princebourg many barges were in evidence. Those at the side of the canal were taken to be moored up, and those in the middle to be moving, though the slowness of their speed made it impossible to decide on their direction, for from a height of ten thousand feet they seemed to be stationary. About a dozen Hun machines were rising from aerodromes at Passementerie, away to the left, but if they were after us the attempt to reach our height in time was futile.

Between Le Recul and Princebourg we dropped fifteen hundred feet below the three rear machines, which hovered above us. Though I was far from feeling at home, it was necessary to sweep the surrounding country for transport of all kinds. This was done almost automatically, since I found myself unable to give a whole-hearted attention to the job, while the infernal motif of the engine's rag-time drone dominated everything and invited speculation on how much lower we were than the others, and whether we were likely to reach a friendly landing-ground. And all the while a troublesome verse chose very inopportunely to race across the background of my mind, in time with the engine, each cut-out being the end of a line. Once or twice I caught myself murmuring—

Slightly to the east of Princebourg, a new complication appeared in the shape of a small German machine. Seeing that our bus was in difficulties, it awaited an opportunity to pounce, and remained at a height slightly greater than ours, but some distance behind the bus that acted as rearguard to the party. Its speed must have been about ten miles an hour more than our own, for though the Hun pilot had probably throttled down, he was obliged to make his craft snake its way in short curves, so that it should not come within dangerous range of our guns. At times he varied this method by lifting the machine almost to stalling point, letting her down again, and repeating the process. Once I saw some motor transport on a road. I leaned over the side to estimate their number, but gave up the task of doing so with accuracy under the double strain of watching the Hun scout and listening to the jerky voice of the engine.

As we continued to drop, the German evidently decided to finish us. He climbed a little and then rushed ahead. I fired at him in rapid bursts, but he kept to his course. He did not come near enough for a dive, however, as the rest of the party, two thousand feet above, had watched his movements, and as soon as he began to move nearer two of them fell towards him. Seeing that his game was spoiled the Boche went down steeply, and only flattened out when he was low enough to be safe from attack.

Near St Guillaume an anti-aircraft battery opened fire. The Hun pilot then thought it better to leave Archie to deal with us, and he annoyed us no more. Some of the shell-bursts were quite near, but we could not afford to lose height in distance-dodging, with our machine in a dubious condition twenty-five miles on the wrong side of the trenches.

ToutprÈs, to the south-west, was to have been included in the list of towns covered, but under the adverse circumstances V. decided not to battle against the wind more than was necessary to get us home. He therefore veered to the right, and steered due west. The south-west wind cut across and drifted us, so that our actual course was north-west. Our ground speed was now a good deal greater than if we had travelled directly west, and there was no extra distance to be covered, because of a large eastward bend in the lines as they wound north. We skirted the ragged ForÊt de Quand-MÊme, and passed St Guillaume on our left.

The behaviour of the engine went from bad to worse, and the vibration became more and more intense. Once again I thought it would peter out before we were within gliding distance of British territory, and I therefore made ready to burn the machine—the last duty of an airman let in for the catastrophe of a landing among enemies. But the engine kept alive, obstinately and unevenly. V. held down the nose of the machine still farther, so as to gain the lines in the quickest possible time.

Soon we were treated to a display by the family ghost of the clan Archibald, otherwise an immense pillar of grey-white smoky substance that appeared very suddenly to windward of us. It stretched up vertically from the ground to a height about level with ours, which was then only five and a half thousand feet. We watched it curiously as it stood in an unbending rigidity similar to that of a giant waxwork, cold, unnatural, stupidly implacable, half unbelievable, and wholly ridiculous. At the top it sprayed round, like a stick of asparagus. For two or three months similar apparitions had been exhibited to us at rare intervals, nearly always in the same neighbourhood. At first sight the pillars of smoke seemed not to disperse, but after an interval they apparently faded away as mysteriously as they had appeared. What was meant to be their particular branch of frightfulness I cannot say. One rumour was that they were an experiment in aerial gassing, and another that they were of some phosphorous compound. All I know is that they entertained us from time to time, with no apparent damage.

Archie quickly distracted our attention from the phantom pillar. We had been drifted to just south of Lille, possibly the hottest spot on the whole western front as regards anti-aircraft fire. Seeing one machine four to five thousand feet below its companions, the gunners very naturally concentrated on it. A spasmodic chorus of barking coughs drowned the almost equally spasmodic roar of the engine. V. dodged steeply and then raced, full out, for the lines. A sight of the dirty brown jig-saw of trenches heartened us greatly. A few minutes later we were within gliding distance of the British front. When we realised that even if the engine lost all life we could reach safety, nothing else seemed to matter, not even the storm of shell-bursts.

Suddenly the machine quivered, swung to the left, and nearly put itself in a flat spin. A large splinter of H.E. had sliced away part of the rudder. V. banked to prevent an uncontrolled side-slip, righted the bus as far as possible, and dived for the lines. These we passed at a great pace, but we did not shake off Archie until well on the right side, for at our low altitude the high-angle guns had a large radius of action that could include us. However, the menacing coughs finally ceased to annoy, and our immediate troubles were over. The strain snapped, the air was an exhilarating tonic, the sun was warmly comforting, and everything seemed attractive, even the desolated jumble of waste ground below us. I opened a packet of chocolate and shared it with V., who was trying hard to fly evenly with an uneven rudder. I sang to him down the speaking-tube, but his nerves had stood enough for the day, and he wriggled the machine from one side to the other until I became silent. Contrariwise to the last, our engine recovered slightly now that its recovery was not so important, and it behaved well until it seized up for better or worse when we had landed.

From the aerodrome the pilots proceeded to tea and a bath, while we, the unfortunate observers, copied our notes into a detailed report, elaborated the sketches of the new aerodromes, and drove in our unkempt state to Headquarters, there to discuss the reconnaissance with spotlessly neat staff officers. At the end of the report one must give the height at which the job was done, and say whether the conditions were favourable or otherwise for observation. I thought of the absence of thick clouds or mist that might have made the work difficult. Then I thought of the cylinder that missed and the chunk of rudder that was missing, but decided that these little inconveniences were unofficial. And the legend I felt in duty bound to write was: "Height 5,000-10,000 ft. Observation easy."