“You have done more than I have in the way of slaughter and destruction,” said Alan. “But there will be some fearful work along the Russian frontier to-morrow morning. The Tsarina, as you call her, is concentrating her forces at Kieff, Vitebsk, Dünaburg, and Vilna for a descent upon Germany. I have ordered those four places to be destroyed as soon as possible after sunrise, and I am just starting now, so you had better come with me and order your ships to follow us.”

Both the commanders felt, as their combined squadrons were winging their way towards the Russian frontier, that the events of the next twenty-four hours or so would go far towards deciding the issues of the war, and therefore the fate of the world.

Alexis had given up the command of the Isma for the night to his first lieutenant, and was travelling on board the Avenger, in order that he and Alan might finally arrange their plans for the terrible deeds that were to be done on the following day. Both of them were serious almost to depression, for it must be remembered that neither possessed that love of fighting and slaughter which distinguishes the professional soldier of the nineteenth century.

Armed with the most awful weapons ever wielded by human hands, they had already, within the space of a few hours, hurled millions of their fellow-creatures into eternity and made thousands of homes desolate which a couple of days ago were happy. Now they were going to repeat the tragedy, on how vast a scale neither of them knew. Before the next sunset a red line of blood and flame would mark the frontier between Russia and Germany.

All the horrors of months of the older warfare would be concentrated into those few fatal hours. Those who were to do battle in the air would hurl their irresistible lightnings at each other more as gods than as men, while on earth the unresisting swarms could only stand in helpless agony of suspense waiting for the death from which there was no possibility of flying.

Within a hundred miles of the frontier the two fleets stopped, and Alexis went on board his own vessel. It was then a few minutes after three in the morning, that is to say, about an hour before sunrise, and the warships were floating in a serene and cloudless atmosphere at an elevation of nearly four miles, or about twenty thousand feet. It was already quite light enough at that elevation for signals to be plainly seen, and a rapid interchange of these took place, communicating the final instructions from the flagships to the commanders of the smaller squadrons into which the fleets were to be divided.

Just as the last signal had been answered, and the vessels were about to separate, a tiny speck of light was seen far away to the westward. A hundred powerful field-glasses were instantly turned upon it, and soon showed it to be a hostile air-ship coming up very fast at an elevation of about three miles. The silvery sheen of her hull instantly betrayed the fact that she was neither an Aerian nor a Federation vessel, for the former were blue and the latter painted dull grey. A moment’s reflection showed that she must have sighted the Aerian fleet, and if she got past would take tidings of its presence to the frontier and destroy all hope of a surprise.

Within twenty seconds of her true nature being made out a signal was flying from the mizzenmast of the Isma, which read, “Shall I stop her?” “Yes. Cripple her if you can. Don’t fire unless necessary,” came the reply from the Avenger, and the Isma at once darted away on her errand.

Alexis, of course, understood that if he struck the enemy with a shell her fragments would fall to the earth, and might probably give the impression that a battle was being fought in the air, and, as they were now so near to the Russian frontier, this was to be avoided if possible. He therefore determined to cripple her without destroying her, and, if he could manage it, to capture her in mid-air, a feat that had never been performed before under similar conditions.