THE night of the 15th of May 2037 was passed in an agony of apprehension by nearly the whole of civilised humanity. The long threatened and universally feared thunder-cloud of war had at last loomed up over the serene horizon of peace in full view of the whole world.

Although the events of the last six years had to some extent prepared the minds of men for the impending disaster, now that the last hour of the long peace was really about to strike there were very, very few among the millions of non-combatants who were able to rise superior to the universal panic.

The ocean terrorism which had paralysed the commerce of the world five years and a half before, fearful as it had been, was, so far as the bulk of humanity was concerned, a terror of the unseen. Ships had gone out to sea and had vanished into the depths, leaving no trace behind them, but the hand that struck the blow had remained invisible.

Now, however, this same terror, magnified a thousandfold, was to come close up to the shores of lands whose inhabitants had never known what it was for man to raise his hand against his brother. To-morrow the sun would rise as usual, the earth would smile, the sea would dance, and the air grow bright and warm under his beams, yet air and earth and sea would be wholly strange to the eyes of men, for they would be invested with terrors hitherto only pictured by the fears of panic.

The air would be charged with death. Beneath the laughing waves great battleships would be speeding swiftly, silently, and invisibly on their errands of destruction, and the fair face of earth would be scarred by the harrow of battle, and seared with the fires of murderous passion.

The ocean traffic of the world had been almost wholly at a standstill for nearly a month. Transports which could complete their voyages before the end of the truce had done so; but since the 1st of May only short voyages had been attempted, for it was known that escape from the attack of a submarine battleship would be absolutely impossible for any vessels that floated on the surface of the water.

The immediate results of this had of course been the dislocation of trade and commerce and ever-increasing scarcity of food in the great centres of population. Impossible, absurd even, as it still seemed to those who had not thoroughly recognised the tremendous gravity of the situation, the inhabitants of the magnificent cities of the old and new worlds were actually within measurable distance, even before a blow had been struck, of seeing the spectre of Famine cross the threshold of their palaces.

In a few days communications by land would be as difficult and as dangerous as those by sea, for, swift as the trains were, their speed was far excelled by that of the slowest air-ship, which could wreck them with a single shot. Bridges would be destroyed, stations blown up, and lines cut in a hundred places at once, till railway travelling would have to cease all over the world.

Thus the most splendid civilisation of all the ages stood trembling on the verge of destruction at the moment when the sleepless eyes of the inhabitants of Alexandria saw the first faint glow of the dawn brightening the eastern sky. No one knew where or how the first blow would be struck in the strange and terrible warfare for the commencement of which the rising of that morning’s sun gave the signal.

There were scarcely any elements in common with the war of the nineteenth century save the slaughter and destruction that it would entail. There could be no marshalling of fleets or warships on the sea, for to be detected by an enemy would be coming very near to being destroyed. Every blow would have to be struck swiftly, silently, and without warning, for only one could be struck, and to fail would be to be lost.

So, too, in the air, as had been proved at Kerguelen and Mount Terror. Everything would depend upon the supreme strategy which enabled the first fatal shot to be sent home that would decide battle after battle without hope for the vanquished to recover from their defeat.

But after all it would be on land that the terrors of the new warfare would be most fearfully manifested. It needed but little effort of the highly-strung imaginations of those who were waiting for the world-tragedy to begin to picture vast armies, magnificent in their strength and splendid in their equipments, marching to grapple with each other on some field of Titanic strife. Suddenly and without warning they would be smitten by an invisible foe floating far above the clouds, or perhaps visible only as a tiny speck of light high in the central blue.

Their battalions would be torn to pieces, their regiments decimated and thrown into confusion, their commanders—the brains of the huge organisms—would have no such protection as they had in the wars of former times, for the aerial artillery would reach everywhere, and the Commander-in-Chief in his headquarters would be as much exposed as the private in his bivouac.

Thus the brain would be destroyed and the body reduced to impotence; disciplined armies would become lawless and unregulated hordes in a few days or weeks, and the organised slaughter of the battlefield would be exchanged for the butchery and plunder of the city carried by assault.

It was little wonder, then, that the world watched the ending of its last night of peace and the dawning of its first day of battle with feelings such as men had not felt for five generations, if, indeed, ever before in the history of man.

It was not a mere war of nations with which men were confronted. The evil genius of a single woman had achieved the unheard-of feat of dividing the human race into two hostile forces so nearly balanced in strength that mutual destruction seemed a not improbable issue of what might after all prove to be the death-struggle of humanity, the collapse of civilisation and the sinking of a remnant of mankind back to the level of barbarians whose children would wander amidst the ruins of their forefathers’ habitations, and wonder what race of demigods had created the wondrous fabrics whose very fragments were splendid.

As the dawn flew round the world on that momentous morning every eye was turned towards the heavens, on every lip there was but one question: Where will the first blow be struck? and in every heart there was but one thought: Will it reach me or my dear ones?

The focus of all human interest was for a moment Alexandria, for it was known that from there the main expeditionary force was to be sent out to, if possible, effect a landing on the shores of Italy, while other expeditions were to start from Tripoli, Tunis, and Oran to effect landings in France and Spain. The bridge across the Straits of Gibraltar from Point Cires to Gualdamesi was to all intents and purposes neutral, since it would have been madness to send trains conveying troops across it when a single shot from the British battery at Gibraltar would have shattered the bridge to fragments.

The forces destined by the Sultan for the invasion of Europe would, therefore, either have to be conveyed in swift transports by sea, protected by squadrons of air-ships and flotillas of submarine battleships, or else they would have to go by land round the Levant by Syria, and so through Asia Minor to the shores of the Dardanelles and the Bosphorus.

As the European shores of these two straits were known to be defended by concealed batteries mounting guns a single shot from which would blow the biggest transport afloat out of the water, the Sultan had decided to make the attempt to invade Italy, France, and Spain by sea, while the Russian forces, with their Asiatic allies, were to attack the central nations from the east.

So far, therefore, as could be foreseen, the Mediterranean would once more be the arena of strife, and on some part of its shores or its waters the first blow of the war would be struck. Every possible preparation for the attack upon Europe had been finally completed immediately after the return of Khalid from the coronation of Olga on the 11th, but beyond the fact that the coasts of Europe, from the Straits of Dover to the Golden Horn, were patrolled by Federation battleships, nothing was known of the dispositions which had been made for the defence of Europe.

Gibraltar, Minorca, Cape Spartivento, Mount Ida in Candia and Olympus in Cyprus formed a chain of Federation posts which, while they had been made impregnable to all attack save long-sustained bombardment from the air, rendered any attempt on the part of large fleets to cross the Mediterranean an extremely hazardous venture.

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.

He remembered how his ancestor, Richard Arnold, in the first Ithuriel, had rammed the Russian war-balloons to the north of Muswell Hill, and resolved to eclipse even that marvellous stroke of tactics. Obeying his will like a living creature, the mighty fabric under his control sank five thousand feet and then began to gather way on a slanting course towards the Moslem air-ships.

The propellers whirled faster and faster, and the quadruple wings undulated with ever-increasing velocity until the crowds in the streets of Alexandria saw something like a swift flash of blue light stream downward from the southern sky, and heard a long screaming roar as though the firmament was being rent in twain above them.

Then three of the air-ships floating in line above their heads seemed to break up and roll over. The crowds held their breath and pointed upwards with one accord in sudden horror, as the crippled air-ships dropped like stones towards the earth. In another moment they struck it, and then, as though the central fires of the earth had burst through in the heart of the great city, there came a crash and a shock that shook the ground like an earthquake spasm.

A vast dazzling volume of flame shot up from amidst a wide circle of blackened ruin, towers fell and roofs collapsed all round the focus of the explosion, the whole atmosphere above the city was convulsed, and the very sea itself seemed to writhe under the stress of the mighty shock, and so, leaving death and ruin and consternation behind her, the Avenger swept out over the Mediterranean at a speed that the eye could scarcely follow, after striking the first blow in the world-war of the twenty-first century.

To say that this sudden and unexpected catastrophe spread panic through the Moslem capital would be but a very inadequate description of the Avenger’s first blow in the world-war. Consternation, wild and unbounded, blanched every cheek, and made every heart stand still as the mighty roar of the explosion burst upon the deafened ears of the inhabitants and then instantly died into silence, broken only by the crash of falling ruins and the screams and groans of the wounded and dying.

The red spectre of war in its most frightful form had suddenly appeared to the terrified and horror-stricken vision of millions of men and women, scarce one of whom had ever seen a deed of violence done.

Khalid, like a wise leader, did all he could to prevent the panic spreading to the troops on board the transports by issuing peremptory orders for the expedition to start at once. At the same time he signalled for half a dozen air-ships to ascend as far as possible and attempt to discover the source from which the inexplicable attack had come, an errand destined to be entirely fruitless.

In orderly succession the hundred huge transports, each carrying from eight to ten thousand men, left the outer basin in two long lines in the rear of the fifty air-ships already in position.

A hundred submarine battleships took up their stations five hundred yards in advance of the first line of transports. Fifty of these sank to a depth of thirty feet, and shot two thousand yards ahead as soon as the whole flotilla was in motion, while the other fifty ran along the surface of the water with their conning-towers just showing above the waves, ready to sink in obedience to any signal that their commanders might receive from the air-ships, which commanded an immense range of vision over the waters.

To all appearance the enemy was content with the one terrible blow that had already been struck. The smooth, sunlit sea betrayed no trace of a hostile vessel, and as far as the glasses of those on board the air-ships could sweep the sky nothing but the blue atmosphere, flecked here and there with white, fleecy clouds, could be seen.

But the Moslem commanders were far from being deceived by these peaceful appearances. From Sultan Khalid, who was commanding the expedition in person, to the engineers who worked the transports, all knew that the invisible line of the Federation patrols had to be passed somewhere in the depths of the sea before the shores of Italy could be reached.

The speed of the three flotillas was limited to twenty-five miles an hour, in order that there might be no headlong running into danger, and the commander of each of the submerged battleships had orders to rise to the surface the instant that his tell-tale needle denoted the presence of an enemy, and signal the fact to the rest of the squadron. The transports were then to stop, and were not to resume their passage until the battleships had cleared the way for them. The first division was to engage the enemy, while the second was to remain on the surface ready to defend the transports in case of need.

For six hours the expedition proceeded on its way north-west by west from Alexandria without interruption. The intention was to pass about a hundred miles to the south of the Federation post at Candia, between which island and the Cape Spartivento the ocean patrol would most likely be met with.

Soon after twelve those on board the Sultan’s flagship detected half a dozen little points of light shining amidst the waves to the north-westward. They could be nothing else but the scout-ships of the patrol; and although they were nearly ten miles away, a couple of shells were discharged at them from the Al Borak’s bow gun, more as a warning to the Moslem flotilla than in the hope of doing any damage. Whether they did or not was never known, for before the explosion of the shells was seen in the water the points of light had vanished.

Signals were at once made from the flagship ordering the transports to stop, and the second division of battleships to stand by to protect them. A dozen remained on the surface of the water, running round and round the now stationary troopships in concentric circles. The others sank to varying depths, and scattered until the vague fluctuations of their needles showed that they were more than a thousand yards from each other and the transports.

As the first division had orders to keep more than two miles in advance as soon as an enemy was discovered, there would be no danger of ramming friend instead of foe. It ran on for seven miles after the main body stopped. It was moving in a single line, the vessels being at an equal distance apart, so that, with the exception of the two ships at the extremities of the line, the attraction of the steel hulls on the needles should be neutralised, and therefore only give indications of vessels ahead.

At the end of the seventh mile the tell-tales ceased their wavering motions and began to point steadily, in slightly varying directions, ahead. The moment they did so the engines were stopped and the flotilla rose to the surface of the water. Their commanders found themselves out of sight of the transports, but the Al Borak, attended by ten other air-ships, was floating about a thousand feet above them. From the flagship’s mainmast-head flew the signal—“Fleet eight miles to the rear. Enemy ahead. Sink and ram.”

The order was instantly obeyed by the whole division, and the fifty battleships simultaneously sank out of sight to engage the invisible enemy, while the Sultan and his companions on board the air-ships waited in intense anxiety to see what the next few fateful minutes would bring forth.

No human eye could see what work of death might be going on down in the depths of the sea. Even those who took part in it would know it only by its results, and of these only the victors would know anything. They would reappear on the surface of the waves, but the vanquished would never rise again.

Minute after minute passed and still the anxious watchers on the air-ships saw nothing. The bright, sunlit waves rippled on over the abyss in which the conflict must by this time be almost over. Five, ten, fifteen minutes passed, and still no sign. Had Khalid been a mile or two farther on and closer down to the surface of the sea, he would have seen streams of air-bubbles rising swiftly here and there and instantly breaking. But from where he was he could see nothing.

Five more minutes went by and suspense gave place to apprehension. Had the whole of the first division simply sunk to its destruction into some invisible trap that had been laid for it deep down in the watery abyss? If not, how came it that not even one of the battleships had risen to the surface to tell the tale of victory or defeat?

Khalid knew that the squadron would obey orders and hurl itself at full speed, that is to say, at some hundred and fifty miles an hour, upon the enemy the moment the tell-tales found their mark. In two or three minutes—five at the outside—their rams must either have done their work or failed to do it. If they had done it they would have risen to the surface; if they had failed and themselves escaped destruction they would still have risen.

Now twenty minutes had passed and not one of the fifty battleships had reappeared. What could this mean but disaster?

And disaster it did mean, but great as it was it was as nothing compared with the frightful catastrophe which followed close upon it. All eyes on board the air-ships were so intently fixed upon that portion of the sea where the squadron was expected to rise again that no one thought for the moment of looking back towards the transports until the dull rumbling roar of a series of explosions came rolling up out of the distance.

Instantly every glass was turned in the direction whence the sound came, and Khalid saw his great fleet of troopships tossing about in the midst of a wild commotion of the waves, out of which vast masses of white water spouted as if from the depths of the sea, and amidst these ship after ship heeled over and sank into the white seething waters.

Uttering a cry of rage and despair, he headed the Al Borak at full speed towards the scene of the disaster. In three minutes he was floating over it, helpless to do anything to avert or even delay the swift destruction that was overwhelming the splendid fleet. Distracted by impotent rage and passionate sorrow for the fate of his soldiers and sailors, who were being slain hopelessly and by wholesale beneath his eyes, he watched the awful submarine storm rage on, wrecking ship after ship, and swallowing them up with all the thousands on board in the boiling gulfs which opened ever and anon amidst the waves.

When the first panic passed, the transports which were still uninjured scattered and headed away as fast as their engines would drive them to the southward, where the only chance of safety seemed to lie. But there was no escape for them from their invisible and merciless enemies.

The fate of one magnificent transport, the flagship of the fleet, may be described as an illustration of the general disaster. She was a vessel of fifty thousand tons measurement, and her crew and complement of troops numbered together nearly twenty-five thousand. She escaped the first discharge from the submarine torpedoes unharmed, and heading southward with her triple propellers revolving at their utmost velocity, rushed through the water at a speed of more than forty nautical miles an hour.

She had scarcely gained a mile on her course when the glass-domed conning-tower of a battleship appeared for an instant above the waves. Before Khalid, not knowing whether it was friend or foe, could make up his mind to fire on it, it disappeared again.

A few seconds later the great ship stopped and shuddered with some mighty shock, as though she had run head-on to a sunken reef, and heeled over to one side. Then came a dull roar, a huge column of white foaming water rose up under her side amidships, and she broke in two and vanished in the midst of a white space of swirling eddies.

Such scenes as this were occurring simultaneously in twenty different parts of the naval battlefield. The foe never showed himself save for an instant. Then came the blow that meant destruction, and the victim vanished. There was none of the pomp and pageantry of modern naval warfare; no splendid armaments of mighty ironclads and stately cruisers vomiting thunder and flame and storms of shot and shell at each other, nor were there any rolling masses of battle smoke to darken the brightness of the sky.

The occupants of an open boat five miles away would not have known that the most deadly sea-fight ever waged since men had first gone down to the sea in ships was being fought out under that smiling May-day sky.

One after another the flying transports were overtaken, rammed, or blown up and sunk by the pitiless monsters which unceasingly darted hither and thither a few feet below the surface of the water, and in less than two hours after the first alarm had been given the last of the hundred transports which had sailed that morning from Alexandria had gone down a shattered wreck into the abysses of the Inland Sea.

There was no chance of saving the drowning wretches who managed to escape from the eddies of the sinking ships, as there would have been in a naval battle of to-day. The air-ships could not do so without sinking to the waves, and so making themselves marks for the irresistible rams and torpedoes of their enemies, who themselves could not be merciful, even if they would, shut up as they were in the steel leviathans whose only use was destruction.

Khalid the Magnificent, with a heart well-nigh breaking with rage and shame and sorrow, watched in passionate helplessness the destruction of his splendid fleet and the drowning, like rats in a pond, of the soldiers who were to have borne the banner of the Crescent over the conquered fields of Christendom.

More than a million men had perished beneath his eyes, and he had not been able to fire a shot to help them, although he was in command of an aerial fleet which could have dispersed an army or wrecked a city between sunrise and noon.

But the strangest part of the strange battle was yet to come. After the last of the transports had disappeared, the attack ceased and the assailants vanished. In a few minutes the sea was as calm and bright as ever, and only a few bits of broken wooden wreckage floating here and there betrayed the fact that anything out of the common had happened.

The remnant of the Moslem squadron rose to the surface and signalled for instructions. Only twenty of them remained uninjured out of the hundred that had gone into the fight. Before the signals could be returned there was a loud hiss and a swirling noise as of some huge body rushing at a furious speed through the water, and a great battleship leapt up out of the nether waters, and hurled herself at a speed of nearly two hundred miles an hour into the midst of the floating squadron.

Her gleaming ram of azurine tore its way through the sides of three vessels in such swift succession that, almost before their fragments had time to sink, her huge bulk vanished under the waves again. But hardly was her work done than a second battleship charged into the paralysed squadron, sending two of its members to the bottom and crippling three more before she, too, vanished into the safe obscurity of the depths.

A third was met by a storm of shells from the air-ships, which burst round her and under her just as she came to the surface, and blew her out of the water in fragments. Heedless of this, a fourth plunged fiercely through the foaming area of the explosion, and had wrecked two more Moslem vessels before a shell smashed her propeller and laid her helpless on the water. Two of the Moslems instantly backed out and rushed at her, tearing two great ragged holes in her side and sinking her instantly, only to be sunk themselves in turn by a fifth charge from below.

Scarcely had this last foe disappeared in safety than a swarm of torpedoes, converging from all sides, encircled the remaining Moslem battleships. Some plunged beneath the waves to escape them, but these never reappeared. The remainder, torn and twisted and shattered by a series of explosions that flung the water mountains high all round them, sank like stones, and when the sea once more settled down, the grim work of death had been completed.

The fate which had so swiftly overwhelmed the expedition that had set out from Alexandria had almost simultaneously befallen four other expeditions which had started at the same hour from Tripoli, Tunis, Algiers, and Oran. The one disaster had been an almost exact reproduction of the others.

The same order, formation, and tactics had been observed in each of the five cases, and each of the five squadrons of transports and fleets of submarine battleships had been overwhelmed and completely destroyed by the same mysterious fate. Of five hundred transports and the same number of battleships which Sultan Khalid had possessed at sunrise on that fatal 16th of May not a single one remained by sundown, and of the more than three million souls who had manned the five fleets not one man survived.

Of the strength or the losses of the enemy that had wrought this appalling and unheard-of destruction within such a brief space of time nothing could, in the nature of the case, be known by those who had seen only some of its effects from the decks of the air-ships which floated almost helplessly over the waves which were engulfing their naval consorts. The work of annihilation had for the most part been done in the dim and silent depths of the sea, and all that they knew was the number of those of their own comrades who had gone to battle and never returned.

And yet to all practical intents and purposes these five stupendous blows which had simultaneously crushed the Moslem sea-power and half crippled the military strength of the Sultan had been struck by one hand. In other words, the victory of the Mediterranean was due to two inventions which had been made and perfected by Max Ernstein, who had been transferred from Kerguelen and appointed Admiral in Command of the whole Mediterranean forces of the Federation.

One of these was a highly improved form of an apparatus which had just come into use on board battleships and cruisers when the War of the Terror broke out. This was an electrical contrivance which gave warning, more or less reliable, of the approach of torpedoes, by translating the aqueous vibrations set up by them into sound-waves, which increased in intensity as the hidden destroyer came nearer.

This invention had been lost sight of when all the warships of the world were sunk in the South Atlantic after the proclamation of the Universal Peace. Ernstein’s was therefore a new discovery, or rediscovery, but the advantages of his position, far ahead of the scientific skill of the nineteenth century, had enabled him to produce a much more perfect instrument, and his apparatus, which was attached to all the battleships of the Federation, not only gave warning of the approach of an enemy, but indicated his direction, the number of revolutions at which his propellers were working, and his distance at any given moment.

This not only enabled the commander of a Federation battleship to detect the presence of an enemy, but it enabled him to distinguish between friend and foe. As soon as the phonetic indicator showed that another ship was approaching he stopped his own propellers, started them, and stopped them again.

The vibrations thus set up and interrupted would be conveyed to the indicator of the approaching ship, if she had one, and she would at once return the signal. If the signal was not returned it was safe to conclude that the coming vessel was an enemy and could be rammed accordingly.

When this invention replaced the tell-tale needle that had been in use a year before, an alteration in tactics became necessary, and the fighting order became more extended. A mile instead of a thousand yards was now the limit within which the Federation battleships were not permitted to approach each other, save under special circumstances. Every vessel acted as an independent unit, subject only to the general instructions.

Ernstein’s second invention was of a simpler but none the less effective character. Knowing that the Moslem and Russian squadrons would be forced to trust entirely to their tell-tale magnetised needles, he had devised a plan for making these worse than useless. As soon as the phonetic indicator told him that an enemy was coming, the commander of each of his battleships dropped a thin rope of insulated wire down thirty or forty feet into the water below him.

The lower end of this cable was a powerful electro-magnet, through which a current of electricity was kept passing along the wires. The attraction of this magnet was far stronger than that of the hull of the vessel, and consequently the needles of the enemy were deflected downwards, and gave a totally erroneous idea as to the depth at which the Federation ship was floating.

Thus when the first division of the Moslem submarine squadron charged at what its commanders thought were the hulls of their enemies, their rams passed harmlessly underneath them, merely striking the magnet and knocking it aside. The moment they had passed the magnet, its attraction swung their needles back, and showed that some mysterious mistake had been committed, but before they had time to turn and seek the mark afresh the Federation ships were upon them, and their rams had rent their way into their sides.

In this manner every ship of the first division had been destroyed within three minutes after it had made its first and last charge. Then the Federationists had risen to the surface for an instant to reconnoitre by means of the arrangement of mirrors previously described, and sinking again had worked their way back towards the transports, formed in a huge circle round them, and had sent torpedo after torpedo into their midst.

As soon as the flotilla had been thrown into confusion they had converged until they could communicate with each other by means of their submarine signals, and after that they had attacked the enemy singly. Ship after ship charged into the mÊlÉe, did her work, and retired, if she escaped destruction, to give place to another.

Only twenty Federation ships had been engaged in each of the five battles, and of these forty in all had been destroyed, a loss utterly disproportionate to the gigantic damage that had been done to the enemy.

Khalid the Magnificent divined intuitively that the disaster which had overwhelmed the expedition which he had commanded in person was only a portion of a result achieved by some elaborate and consummately-conceived scheme of defence which must have been simultaneously put into operation against his other expeditions. What had succeeded against his own might well have been expected to have succeeded against them.

He at once despatched four squadrons of ten air-ships each to Tripoli and Tunis, Algiers and Oran, with orders to collect all attainable information, and to return to Alexandria as soon after sunset as possible. Then he turned the prows of the remainder of his fleet towards his capital, and gave the signal for full speed ahead.