So they received with a grim joy the summons to battle which had been so long expected. Four thousand of them manned the air-ships, the rest occupied the mountain batteries, and within a quarter of an hour of the bringing of the news the war-ships had mounted into the air, and the great guns of the batteries were ready to hurl their projectiles upon the advancing foe. It was a spectacle to make angels weep and devils laugh, this last marshalling of the forces of human hate and hostility in the closing hours of the life of humanity and on the threshold of eternity. It seemed that the Tragedy of Man was to be played out to the bitter end, and that human strife was only to cease on earth with the destruction of the world. This, too, was the work of a single woman inspired by quenchless hatred and insatiable ambition and a pride of spirit which, in its haughty incredulity, still refused to believe that the end of her conquering career had come. Pitiless and without scruple to the end, Olga, while she was recovering from her wound under the shelter of the Sultan’s roof, had managed, with the aid of her waiting-woman Anna, not only to poison the Grand Vizier Musa and Hakem the astronomer, but also to bring Khalid himself into the same state of moral slavery in which she had so long held Alan and Alexis. It was she who had brought this fleet from Alexandria to Aeria. Once under the fatal spell of her will-poison, she had commanded Khalid to revoke the orders that he had given for peace, and he had obeyed. A fleet of more than five hundred air-ships had been collected, and, taking Khalid with her on board the _Revenge_, so that there should be no chance of his recovering his volition, she had come to fulfil the prophecy which Paul Romanoff uttered when in the last hour of his life he had declared that one day the Eagle of Russia should fly over the battlements of Aeria. All the materials for constructing ten air-ships had been taken into the caverns, so that in the event of the remnant surviving the empire of the air should still be theirs, but the _Alma_ and the _Isma_ still lay outside the entrance when the other ships had risen into the air. At the supreme moment a controversy had arisen as to whether or not Alan and Alexis--the latter of whom had been placed without question among the chosen, not only because of his unequalled engineering skill, but also because without him a daughter of the House of Arnold would have died of her own will--should or should not take part with their companions in the near approaching conflict. This dispute was brought to a sudden close by Alan, who, with a sudden inspiration, cut short all the loving entreaties that were being made to him to take refuge in the caverns and avoid the chance which in the heat of the conflict might destroy with him the male line of the descendants of the first conqueror of the air.