By eight o'clock the guns of the castle were nearly all dismounted, and the number of its effective defenders had been so much diminished, that it was found necessary to desert the ramparts, and retire within the great tower, which from the thickness of its walls offered at least a temporary security. On this last place of refuge, the Hasnagee hoisted a black flag, in token of his determination to die rather than yield, according to the promise which he had made to his master. He was however released from this promise by a signal from the Casauba indicating the Dey's wish that the fortress should be abandoned; this was accordingly done and the garrison escaped just as the French had effected a practicable breach in its wall. General Hurel who commanded the nearest battery, was then in the act of advancing with his men towards the opening, when suddenly the earth shook, the towers of the castle were seen to totter, flashes of flame and dense clouds of smoke rose above them, and an explosion ensued which momentarily stunned the ardent soldiers. The {526} Algerines, before they evacuated the castle, had fired a slow match communicating with the powder magazines in its vaults, and the last and strongest defence of Algiers was utterly destroyed. As the smoke vanished, the walls of the fortress were seen rent and shattered by the terrible concussion; the great tower was reduced to a few shapeless masses, and the ground in the environs was covered with fragments of wall, corpses and even cannon, which had been projected into the air by the violence of the explosion. The French soon recovered, and rushing forward with shouts of triumph, planted their standard among the smoking ruins; scarcely too was this done, ere the prompt and skilful engineers were directing the workmen to clear away the interior of the place, and stop the breaches in its outward walls, so as to protect it against the assaults of its former possessors. The ruins of the Star fort were also occupied, and preparations were made for erecting batteries on them for the bombardment of the city.