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.