When the sun at last rose over the hills of Syria and Sinai, and the watchers in the streets and on the housetops of Alexandria heard the voice of the Muezzin calling the first hour of prayer and the last hour of the world’s peace, the bright blue waves of the Inland Sea lay smiling and sparkling in its earliest beams, betraying not a trace of the hidden forces which waited but for the signal that might come either from land or sea or sky to begin the work of desolation. The harbours of the city were thronged with shipping, great transports lined the miles of quays whose network fronted the seaward verge of the Moslem capital. Some of the basins swarmed with the half-submerged hulls of scores of battleships waiting to take up their position as convoys to the flotilla which, if the Sultan’s plans succeeded, would, within the next twelve hours, land nearly four million troops on European soil. In the air, at elevations varying from five hundred to ten thousand feet, a squadron of two hundred aerial cruisers kept watch and ward against a surprise from the upper regions of the air. By the time the day had fully dawned, land and sea and sky had been scanned in vain for a sign of an enemy’s presence. The sailing of the flotilla of transports had been fixed for six o’clock by Alexandrian time, and already the battleships were moving out into the open to take up their places in advance of the fleet of transports. Fifty air-ships had ranged themselves in a long line to seaward at an elevation of two thousand feet to protect the transports from an aerial assault, and the transports themselves were moving out to form in the basin behind the breakwater, whence they were to commence their voyage. Sultan Khalid, on board his aerial flagship _Al Borak_--named after the winged steed which, according to the old legend, had borne the Prophet from earth to the threshold of the Seventh Heaven--superintended in person the last preparations for the departure of his great armament. Flying hither and thither, now soaring and now sinking, he inspected first the cruisers of the air and then the flotillas of the seas, and at last, when all was ready, he took his place by one of the bow guns of the _Al Borak_ to fire the shot that was to be the signal for the expedition to start. But a higher intelligence and a greater tactical ability than his had already determined that the signal should be given in very different fashion. Fifty miles to the south towards the Lybian desert, high in air, fifteen thousand feet above the earth, a solitary air-ship hung suspended in the central blue.