"A launch will put off from the mole for the flagship at ten o'clock," Dave informed him. "We may as well go down to the mole and wait."

Twice, on the way, after leaving the more crowded parts of the city behind, the three were challenged by English sentries invisible in the darkness.

"Who goes there?" came the sentry's hail in each instance.

"Officers from the American flagship," Darrin answered for the party.

"Pass on, gentlemen," came the response out of the darkness.

At all times strict watch over all comers outside the British army service is kept at Gibraltar, and after dark this vigilance is doubled.

"On a moonless night like this, one would imagine that Gibraltar, save for the few blocks of 'city,' held few human beings," murmured Dan, as the three continued on at a quiet walk toward the water front. "One gets the impression that there are but a few sentries, sprinkled here and there, yet we know there are thousands of British soldiers scattered over this rock."

"Hardly scattered," smiled Dave Darrin. "Except for the guard, men and officers are alike in barracks, and many of the barracks are at rather long distances from the fortifications."

Nor are the fortifications to be found along the water front. Back on the great hill of rock are gun embrasures, often cut into the face of the rock itself. Back of the embrasures are galleries cut through the stone, and here, in time of siege, the soldiers would stand behind the huge guns.

Gibraltar's harbor is small, though large enough to hold a great fleet. In the days when cannon had shorter range than now, a British fleet might have hidden in the harbor and been secure against all the fleets of the world, for the guns of the huge fortress could have sunk the combined navies of the world, had they attempted to enter the harbor. In these modern days Gibraltar is not so secure, for the heights of Algeciras, in Spain, are only about seven miles away. If Spain were at war with Great Britain, or if any other power took the heights of Algeciras from Spain, guns could be mounted on those heights that would dominate the harbor of Gibraltar. None the less, as long as war exists and the huge stone height of Gibraltar remains, the impression of strong military force will abide with the rock.