Titus Livius (Livy), The History of Rome, Book 26
Frank Gardner Moore, Professor Emeritus in Columbia University, Ed.

45. meanwhile the Carthaginian had now fully manned the walls with armed men, and he had a great number of missiles ready at hand out of his immense reserves. [2] but neither men nor missiles nor anything else defended the walls so much as the walls were their own defence. for few ladders could reach to their height, and the higher these were the weaker. [3] and so since the highest man could not climb over, but nevertheless others kept coming up, the ladders were breaking by the mere weight. some men, although the ladders stood, owing to the dizziness produced by the height fell to the ground. [4] and while everywhere men and ladders were dropping, [p. 175]and the enemies' boldness and zest were increasing¹ just because of their success, the signal for the recall was given.² [5] this gave the besieged not only the hope of present respite from such conflict and effort, but also confidence for the future that the city could not be taken by ladders and encirclement; that siege —works were difficult and would also give time for their generals to bring aid.

hardly had the first uproar been stilled when Scipio orders the ladders to be taken from men now weary and wounded, by others who were fresh and uninjured, and that an attack in greater force should be made upon the city. [6] as for himself, having been informed by fishermen of Tarraco³ who had crossed the lagoon everywhere, now in light vessels, now, when [7??] these would go aground, through shallow water, that an easy crossing on foot up to the wall was possible, Scipio, when word was brought to him that the tide was ebbing,⁴ led five hundred armed men with him to the place. [8] it was about the middle of the day,⁵ and in addition to the draining away of the water of itself as the tide ebbed seaward, a fierce north wind also had sprung up and was carrying the receding lagoon in the same direction as the tide, and had so laid bare the shoals that in one place the water was up to the navel only, in another scarcely reached beyond the knees. [9] what he had ascertained by painstaking and calculation, Scipio represented as a miracle and an act of the gods, who for the passage of the Romans were diverting the sea, he said, and draining lakes and opening up ways never before trodden by man's foot. and he bade them to follow Neptune as their guide on the march, and to make their way straight across the lagoon to the walls.

[p. 177]