In the mean time, Cortes had brought the fleet out on the lake, and after various manœuvres, proceeded to attack a rock near the city, where a large number of the inhabitants had fled for refuge. The Mexicans, perceiving his design, sent out their whole naval force (consisting of four thousand canoes) against his brigantines. Cortes now moved fairly out into the lake, and formed his fleet in the shape of a crescent to receive them. As they came near, the sails of the brigantines were spread, and they dashed through them, overturning some, and scattering the rest, to the great loss of the Mexicans. Olid had now reached his post, and from the temple at Cojohuacan saw the conflict on the lake. He instantly pushed along the causeway toward the city, drove the Mexicans from some of the trenches, and took possession. Cortes now attacked the bastion called Xoloc, situated at the angle made by the junction of the roads of Cojohuacan and Iztapalapan. The Mexicans defended the place with great obstinacy; multitudes fell in their efforts to save it, but it was stormed and taken. As this was a spot of great importance, and in direct communication with the division of Olid, Cortes determined to establish his camp here. The three divisions were now on the three causeways, and, as the principal attacks of the enemy were from the canoes that lined them, he distributed his fleet so as to protect the three divisions in their three efforts against the city--giving orders that they were to be managed in strict obedience to the three officers in command. The siege now regularly commenced.
From this moment, a series of attacks, retreats, skirmishes, and manœuvres, were going on upon the causeways. The causeway of Tacuba was the shortest, and it was supposed that Alvarado would be the first, therefore, to enter the city. But the fact that it was the shortest caused it to be the most carefully guarded. Every morning, Alvarado renewed his attempt, and each day met with a sharp opposition. At night, the Mexicans repaired whatever damage he had done, and in the morning showed themselves as stubborn as ever; while the Spaniards, regardless of wounds, endeavored to push their way onward to the capital, and were continually disappointed in their hope of reaching it. Alvarado perceived now, to his sorrow, that the destruction of the aqueduct of Chapoltepec had not taken from the city its supply of water. Canoes were seen continually by night bringing casks from the towns on the borders of the lake. Provisions were brought in the same way; thus defeating the hope of reducing the city by famine. Two of the brigantines were set to watch these boats and intercept them, but the cunning of the Mexicans defeated this. Their canoes were sailing in every direction, to beguile them. So far from being taken themselves, they even contrived to tempt the two brigantines near the border of the lake, where thirty of their largest boats lay in ambush. An attack was instantly made: the brigantines could not well be worked in that position; every Spaniard was wounded, and one of the captains killed. To increase the difficulty of the siege, periodical rains now set in; these, however, did not deter Alvarado and his followers from their attempts, though these attempts were still unsuccessful. Whatever advance he made, however, was a safe one; if he gained a foot of ground, he kept it. Houses were destroyed and ditches filled behind him as far as he passed, to enable him to make good his retreat, if it became necessary. Very much the same scenes were passing on the other causeways. Daily efforts were made, both by land and water, to force an entrance into the city, and all proved unsuccessful.