Punctually at the appointed time the first of the biplanes left the aerodrome, followed at stated intervals by the rest. In spite of the howling wind the ascents were carried out without a hitch.
The secret battleplane was the last to leave. Almost silently as compared with her consorts she rose evenly and swiftly from the ground, and headed off in the direction the others had taken.
In the pale morning light the far-flung double line of British machines could hardly be distinguished against the angry red glow on the eastern horizon, although in the upper regions the deep bass hum of their exhausts could be distinctly heard.
As they neared the lines of opposing trenches three or four Fokkers rose with the evident intention of intercepting the raiding machines; but thinking better of it, they volplaned earthwards.
At length, far above the storm-driven clouds that hid every detail of the country from their sight, the raiders pursued an even and uninterrupted flight, piloted on a compass course by the flight commander in the leading biplane of the right column. With the wind almost dead aft navigation was a fairly simple matter. There was no need to trouble about "side-drifts." All that had to be done was to fly continuously in a straight line until it was judged that the machines were approaching their objective and then descend below the clouds and verify their position by reference to a map and a recognition of conspicuous landmarks.
The "maps" had been especially supplied for the raiding airmen's use by the French government, and were the result of careful aeronautical observation work in pre-war days. In a strict sense they could not be called maps, as they consisted of an elaborate series of enlarged photographic views taken from an altitude of about eight hundred metres, and embraced practically every mile of country between the Franco-German frontier and the environs of Berlin. Their compilation was the direct result of the memorable visit of a Zeppelin to Nancy, where, owing to an accident the gas-bag had been compelled to come to earth. An examination proved conclusively that the airship had been taking aerial reconnaissance of the French fortresses. The French government did not protest: it merely retaliated by making the series of photographic maps that were in the present struggle to play such an important part.
At a quarter to five the leading biplane of the right column began a volplane, the rest of the machines following its example. It was a test in order to verify their position.
For full five minutes each was lost to sight of the other as the air-squadron dipped swiftly through the dense, rain-laden clouds. While it lasted the ordeal was a nerve-racking one, for not only was there the danger of collision in the event of any of the biplanes swinging out of position, but the air was filled with "pockets"—partial vacuum of insufficient density to offer resistance to the planes—into which the airmen fell like stones until the machines "picked up" in the buoyant air beyond. Vicious and erratic currents and eddies, too, added to the pilots' difficulties, while in the midst of the layer of clouds it was almost as dark as midnight.
As the battleplane emerged from the underside of the clouds the lads could discern an extensive town through which flowed a broad river. Viewed from the height of seven thousand feet the town, with the numerous railways radiating from it, resembled a gigantic spider lurking in the centre of its web.
Already the leading biplanes were far beyond the maze of buildings, so it was evident that the city was not Berlin.