conducted their defence with considerable cunning, for midway between the fort and the shore they had, by great exertion and ingenuity, placed several field-guns in well-sheltered spots, hoping that while the fire of the Allies was directed upon the visible batteries, their light pieces could with comparative impunity deliver a galling fire upon the mine-sweepers and the covering torpedo-boat destroyers. Unfortunately for the enemy the far-reaching effect of the heavy shells had resulted in the silencing of the concealed weapons, the men serving them being for the most part slain at their posts. A few had attempted to escape, but before they got beyond the danger zone they too were wiped out by the death-dealing lyddite.

The path Dick had indicated was the one by which the field-pieces had been lowered from the higher ground. It was obstructed in several places by craters torn by the explosion of the British shells, but these afforded no difficulty to the bluejackets.

Wellnigh breathless with their exertions, they reached the fort only to find, to their chagrin, that they had been forestalled by their friendly rivals, for the British flag floated proudly on the captured position.

So devastating had been the fire from the ships that the fort was little better than a shattered heap of brickwork and masonry. Armour-plated shields had been rent like paper, guns of immense size been dismounted and hurled aside like straws. Bodies of the devoted Ottoman garrison lay in heaps. Everything was smothered with a yellowish hue from the deadly lyddite and melanite. Yet several of the huge 80-ton guns were seemingly serviceable. These had to be rendered totally useless by means of slabs of gun-cotton placed well within the muzzle and fired electrically.

Sub-lieutenant Crosthwaite was studiously engaged in making a rough plan of the fort when Sefton, his soot-grimed face red with excitement, approached him.

"I believe I've found a magazine or something, sir," he exclaimed. "It's a funny sort of shop—like a tunnel. There are half a dozen Turks there——"

"Eh?" ejaculated Dick incredulously.

"Dead as door-nails," Sefton hastened to explain. "They look as if they had been suffocated. But the air's pure enough down there now."

Placing his notebook in his pocket, the Sub walked with Sefton across the littered open space in the centre of the fort till they came to a salient angle that faced the northern or landward side. Here the rubble rose to a height of about twenty feet. In places the wall, composed of armour-plate and concrete, had been riven from top to bottom, huge slabs of masonry being held up only by mutual support. On the top of the debris were half a dozen bluejackets, taking advantage of the daylight that still remained in flag-wagging a message to one of the destroyers.

"Here's the show," announced Sefton, pointing to a narrow passage between two immense artificial boulders.

At one time the opening had been much wider, and had been provided with stone steps, but the irresistible shock had contracted the passage, and had buried most of the steps under a heap of rubble.

"We want a lantern for the job," observed Dick. "How did you manage to see? You ought not to have gone on an exploring expedition without someone accompanying you."

"I've brought my electric torch," said the midshipman, studiously ignoring the latter portion of the Sub's remarks.

Unnoticed by the signalling party, the two young officers descended. For twenty yards they had to exercise considerable effort in order to negotiate the bulging sides, but beyond this the passage opened to a width of nearly six feet.

"Mind where you tread," cautioned Sefton, flashing his lamp on the ground. "They are not dangerous, but it isn't pleasant."

Either lying on the stone floor or propped up in a sitting position against the wall were the bodies of several Turkish infantrymen. Most of them were tunicless, while half a dozen 100-pounder shells lying on the ground showed that these men were engaged in bringing ammunition from the magazine when death in the form of lyddite fumes overtook them. There were no visible marks of wounds, so it was fairly safe to conclude that no shell had burst within the tunnel. Further, it showed that somewhere underneath the ruined fort was a still intact store of projectiles which would have to be rendered useless to the Turks before the demolition party returned to their ship.

"Didn't those fellows give you a turn?" enquired Dick.

"A bit at first," admitted the midshipman. "Then when I realized that if they had meant mischief they would have plugged me long before I saw them, I began to think something was wrong with them—and there was."

For nearly a hundred feet the passage zigzagged. With the exception of the dip near the main entrance the floor was almost level. At intervals were niches covered with steel slabs. The place had been electrically lighted, but owing to the destruction of the power-house the lamps were extinguished. Sefton's surmise was correct. It was a magazine, for the peculiar pattern of the electric bulbs in their double glass coverings told Dick the reason for the precaution.

"This is as far as I have been," announced Sefton, pointing to a heavy canvas screen.

"Then we had better both go carefully," added Dick, drawing his revolver, an example that the midshipman eagerly hastened to follow. "Don't go letting rip, mind, without you want to blow the whole crowd of us to pieces. Use your revolver as a moral persuader if there should be any of the enemy skulking here."

Telling the midshipman to keep close to the wall, and to hold the torch at arm's-length with the rays directed into the unexplored part of the tunnel, Dick pulled aside the curtain, half-expecting to find himself confronted by a dozen more or less intimidated ammunition-bearers.

The place was deserted.

"We'll carry on," said the Sub. "By Jove, what a big show! Absolutely shell-proof, I should imagine."

"I can only just hear the row outside," added the midshipman, as the muffled reports of the guncotton explosions showed that the demolition party were doing their work thoroughly.

The magazine was a vault hewn out of the solid rock. It had evidently been in existence for some years, certainly before the modernizing of the fortifications. The ammunition stowed here consisted of shells for the smaller quick-firers, as the absence of tram-lines for conveying the projectiles that were too heavy to man-handle proved.

"Krupp ammunition," reported Sefton, flashing his torch upon the base of one of the brass cylinders. "My word, when our fellows bust that lot up, won't the Turks feel a bit sick!"

"We'll get the men to bring the firing-charges as soon as possible," said Dick. "If we had known of this before, it would have saved no end of work. There would have been no need to have destroyed every gun singly."

"Can't say I envy the fellow who has to fire the stuff," added Sefton. "Hello, what's that?"

The noise of the detonating charges had ceased. Instead came the unmistakable crackle of rifle-firing.

"Look alive!" ordered the Sub. "Our fellows are being attacked."

Brushing aside the canvas screen the two officers made their way along the tunnel as swiftly as the dancing beams of the midshipman's torch permitted.

Before they reached the rise leading to the open air there was a terrific concussion. A waft of hot, pungent fumes bore down upon Dick and his companion. They were compelled to stop, almost choking in the stifling atmosphere. The rays from the torch failed to penetrate the dense brownish cloud of smoke and dust.

"Carry on," spluttered Dick; then noticing that the midshipman seemed on the point of asphyxiation, he seized the torch and, dragging his companion, made for the open air.

Suddenly he came to an abrupt halt. The gap between the crumbling walls no longer existed. They were trapped.