By this speech he easily persuaded his officers to make an attempt upon Tyre. Moreover he was encouraged by a divine admonition, for that very night in his sleep[307] he seemed to be approaching the Tyrian walls, and Heracles seemed to take him by the right hand and lead him up into the city. This was interpreted by Aristander[308] to mean that Tyre would be taken with labour, because the deeds of Heracles were accomplished with labour. Certainly, the siege of Tyre appeared to be a great enterprise; for the city was an island[309] and fortified all round with lofty walls. Moreover naval operations seemed at that time more favourable to the Tyrians, both because the Persians still possessed the sovereignty of the sea and many ships were still remaining with the citizens themselves. However, as these arguments of his had prevailed, he resolved to construct a mole from the mainland to the city.[310] The place is a narrow strait full of pools; and the part of it near the mainland is shallow water and muddy, but the part near the city itself, where was the deepest part of the channel, was the depth of about three fathoms. But there was an abundant supply of stones and wood, which they put on the top of the stones.[311] Stakes were easily fixed down firmly in the mud, which itself served as a cement to the stones to hold them firm. The zeal of the Macedonians in the work was great, and it was increased by the presence of Alexander himself, who took the lead[312] in everything, now rousing the men to exertion by speech, and now by presents of money, lightening the labour of those who were toiling more than their fellows from the desire of gaining praise for their exertions. As long as the mole was being constructed near the mainland, the work made easy and rapid progress, as the material was poured into a small depth of water, and there was no one to hinder them; but when they began to approach the deeper water, and at the same time came near the city itself, they suffered severely, being assailed with missiles from the walls, which were lofty, inasmuch as they had been expressly equipped for work rather than for fighting. Moreover, as the Tyrians still retained command of the sea, they kept on sailing with their triremes to various parts of the mole, and made it impossible in many places for the Macedonians to pour in the material. But the latter erected two towers upon the mole, which they had now projected over a long stretch of sea, and upon these towers they placed engines of war. Skins and prepared hides served as coverings in front of them, to prevent them being struck by fire-bearing missiles from the wall, and at the same time to be a screen against arrows to those who were working. It was likewise intended that the Tyrians who might sail near to injure the men engaged in the construction of the mole should not retire easily, being assailed by missiles from the towers. CHAPTER XIX. THE SIEGE OF TYRE.