As it was impossible for our troops to advance on the causeways, unless their flanks were secured from attacks by water, the flotilla was appointed to this service in three divisions, one of which was attached to each of the three detachments of our land force: Four brigantines being allotted to Alvarado, six to De Oli, and two to Sandoval[6]; twelve in all, the thirteenth having been found too small for service, and was therefore laid up, and her crew distributed to the rest, as twenty men had been already severely wounded in the several vessels. Alvarado now led our division to attack the causeway of Tacuba, placing two brigantines on each flank for our protection. We drove the enemy before us from several of their bridges and barricades; but after fighting the whole day, we were obliged to retreat to our quarters at night, almost all of us wounded by the incessant showers of stones and arrows of the enemy. We were continually assailed on the causeway, by fresh troops of warriors, carrying different banners or devices; and our brigantines were excessively annoyed from the terraces of the houses which stood in the water; and as we could not leave a party to keep possession of what we had acquired during the day, the enemy repossessed themselves of the bridges at night, and repaired and strengthened their parapets and other defences. In some places they deepened the water, digging pits in the shallow places, and placing the canoes in ambush, which they secured against the approach of our brigantines by means of pallisades under water. Every day we were employed in the same manner, driving the enemy before us, and every night we returned to our quarters to bind up our wounds. The cavalry were of no service, on account of the barricades defended by long lances; and the soldiers even did not choose to risk their horses, as their price at this time was from eight hundred to a thousand crowns. One Juan, a soldier from Catalonia, used to heal our wounds by charms and prayers, which by the mercy of God recovered us very fast; and this being observed by our allies, all their wounded men applied to Juan, who had more business on his hands than he was able for. But whether whole or wounded, we were obliged to go out daily against the enemy, as otherwise our companies would have been reduced to less than half their strength. Our ensign was disabled almost every day, as he could not at the same time carry his colours and defend himself from the enemy. We were abundantly supplied with corn, but were much in want of refreshments for the wounded men; our chief resource being _tunas_ or Indian figs, cherries while in season, and a plant called _quilities_ by the natives. The situation of the other two attacks was precisely similar to ours. Every day, when we marched to the attack, a signal was made from the great temple of Tlaltelolco, the great division of Mexico nearest Tacuba, on which the enemy rushed out against us, and