As soon as she got over them the Avenger quickened her course until she was flying round in the same circles and at the same speed as the Russians. This, of course, made her relatively stationary with regard to them, and it was now possible to take aim. Two of the broadside guns, one on each side, were much shorter than the others, and had been specially constructed for firing almost vertically downwards.

Alan stood by one of these and trained it on the first of the Russian vessels, which were coming up in a spiral line. At the right moment he pressed the button in the breech and released the projectile. The shot struck the Russian amidships. They saw the glass deck of the roof splinter, then the blaze of the explosion flashed out, the air quaked, and the next moment the fragments of the Russian warship were falling back upon the earth.

A second and a third shot followed as the other two came into position, and when Alan looked down towards the city again he saw that the four squadrons had taken the alarm, and were rising from the earth and scattering in all directions. This was just what he wanted, for it relieved him of the scruples which had prevented him from firing on them while they lay within the precincts of the city.

In an instant the crew of the Avenger were at their guns, and shell after shell sped on its downward way after the flying ships. Although, under the circumstances, the aim was necessarily hurried, for the captains of the Russian vessels, seeing the terrible disadvantage at which they were placed, had put on their utmost speed, the guns of the Avenger were so smartly handled that nearly a score of the Russians were either blown to fragments or crippled before the squadron escaped out of range.

“Well done!” said Alan. “That will teach them to keep a little smarter look-out next time.” And then he went on to himself—“I wonder whether she was on board one of those that are lying in little pieces down there? I suppose that would be too good luck to hope for, and yet I don’t know, I think her end ought to be something different to that. I wonder what it really will be?”

He ordered his men to cease firing now, and placed the Avenger once more in her old position over Moscow, keeping her at a great elevation to guard against surprise from the squadron he had scattered. A few minutes later two air-ships were reported coming from the south and north. The flash of the sun on their blue hulls proclaimed them friends.

They were the vessels bringing the reports from St. Petersburg and Odessa, and these reports were to the effect that during the whole of the morning trains had been pouring through from the eastward and all the surrounding country towards the Austro-German frontier. Other reports from the westward had been received by the commanders of these two vessels to the effect that the Russian troops were massing along the frontier and seemingly preparing to invade the Federation area from the four points already selected by Alan.

He at once despatched orders by these two courier-vessels to the depôts at Königsberg, Thorn, Breslau, and Budapesth to assemble four squadrons of fifty vessels each, which were to be over the points of concentration at daybreak on the following morning.

These ships were to maintain their greatest possible elevation—that is to say, about three miles and a half—until the sun rose, then if the sky were clear they were to bombard the towns at once from that height; if not they were to use all precautions against surprise in passing through the clouds, and then the commanders were to use their own discretion as to the plan of operation, but Odessa, Kieff, Vitebsk, and Dünaburg were to be destroyed at all hazards as soon as it was certain that the invading forces were concentrated there, and preparing to march eastward.

As soon as these orders had been despatched the Avenger left Moscow, and started at full speed for Gibraltar, where she arrived about four o’clock in the afternoon.