These stations were connected from Gibraltar to Cyprus by telephonic cables, buried beneath the floor of the sea to hide them from the enemy’s cruisers, and also by patrols of battleships constantly moving to and fro in touch with each other along the whole line, and this was the first barrier through which the Moslem Sultan had to force his way before he could land his armies upon the shores of Southern Europe.

This, too, formed what may be termed the first line of defence of the Federation and of Christendom, and although neither the Sultan nor the Tsarina was wholly aware of the fact, it had been strengthened to such a degree that it was expected to prove unbreakable even under the impact of the immense forces that would be brought to bear upon it.

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.

As the sun rose she had moved slowly forward towards the city. As she came within sight of it, Alan Arnold standing in her conning-tower saw through a telescope that commanded a range of a hundred miles the disposition of the aerial fleet above Alexandria. He marked down a group of five air-ships floating some five thousand feet above the centre of the city, and singled them out as the first victims of the war.

He was, of course, far out of range of gun-fire, and to have gone within range and fired on them would have been to expose his single ship to a concentrated hail of projectiles which would have scattered her in dust through the sky. So he determined to open the game of death and destruction by a stroke as dramatic as it was terrible.