When they had thus, by a treaty, shared the city they were about to conquer, they began their preparations for the siege. Towards the commencement of the spring, the Christian army set out from Jerusalem, and the Venetian fleet sailed from the port of Ptolemaïs. The historian of the kingdom of Jerusalem, who was for a long time archbishop of Tyre, stops here to describe the antique wonders of his metropolis. In his recital, at once religious and profane, he invokes by turns the testimony of Isaiah and of Virgil; after having spoken of the king, Hyram, and the tomb of Origen, he does not disdain to celebrate the memory of Cadmus, and the country of Dido. The good archbishop boasts above all of the industry and the commerce of Tyre; of the fertility of its territory, its dyes so celebrated in all antiquity, that sand which is changed into transparent vases, and those sugar-canes which, from that time, were sought for by every region of the universe. Tyre, in the time of Baldwin, was no longer that sumptuous city, whose rich merchants, according to Isaiah, were princes; but it was yet considered as the most populous and the most commercial of all the cities of Syria. It was built upon a delightful beach, which mountains sheltered from the blasts of the north; it had two large moles, which, like two arms, stretched out into the waves, to form a port to which no tempest could find access. Tyre, which had kept the victorious Alexander seven months and a half before its walls, was defended on one side by a stormy sea and steep rocks, and on the other by a triple wall surmounted by high towers. The doge of Venice, with his fleet, entered the port and closed up all issue on the side of the sea. The patriarch of Jerusalem, the regent of the kingdom, and Pontius, count of Tripoli, commanded the army by land. In the early days of the siege, the Christians and the Mussulmans fought with obstinate ardour, and with equal success; but the divisions among the infidels soon came in to second the efforts of the Franks. The caliph of Egypt had yielded half of the place to the sultan of Damascus, to induce him to defend it against the Christians. The Turks and the Egyptians were divided among themselves, and would not fight together. The Franks profited by these divisions, and every day gained great advantages. After a siege of some months, the walls crumbled away before the machines of the Christians; provisions began to be short in the city, and the infidels were ready to capitulate, when discord arose to disunite the Christians in their turn, and was on the point of rendering useless the prodigies of valour, and the labours of the long siege.