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.