Next day, though we were all extremely solicitous for the two captains to remain together, De Oli proceeded with his division to take possession of Cojohuacan, according to the orders he had received from Cortes; but this separation was assuredly extremely ill judged; as, if the enemy had known the smallness of our numbers at the two stations, they might have fallen upon and destroyed us separately, during the four or five days that we remained divided before the arrival of Cortes with the brigantines. In all that time we never ventured to make any more attempts against the Mexican causeways, but the enemy frequently sent bodies of their troops to the main land to make attacks on our quarters, on which occasions we always drove them away.
Sandoval with his division did not leave Tezcuco until the fourth day after the feast of Corpus Christi, when he marched through a friendly country by the south side of the lake, and arrived without interruption in front of Iztapalapa. Immediately on his arrival, he commenced an attack on the enemy, and burnt many of the houses in that part of the town which stood on the firm land; but fresh bodies of Mexican warriors came over in canoes and by the causeway of Iztapalapa to relieve their friends in the town, and made a determined resistance against Sandoval. While the engagement was going on, a smoke was observed to arise from a hill above the town, which was answered by similar signals at many other points around the lake, which were afterwards found to have been made to apprize the enemy of the appearance of our flotilla on the lake. On this, the efforts of the enemy against Sandoval were much relaxed, as their canoes and warriors were recalled to oppose our naval force; and Sandoval was thus enabled to take up his quarters in a part of the town of Iztapalapa; between which and Cojohuacan the only means of communication was by a causeway or mound dividing the lake of Chalco from that of Mexico or Tezcuco, which passage was at that time impracticable in the face of the enemy.
“Before proceeding to the narrative of the siege of Mexico, it may be proper to give some account of the situation of the city of Mexico, and the mounds or causeways by which it communicated with the land at the several posts which were occupied by Cortes for its investment. The city of Mexico was built partly on an island and partly in the water, at the west side of a considerable salt lake, named sometimes the lake of Tezcuco, and sometimes the lake of Mexico, and appears to have been about a mile from the firm land. It communicated with the land by three mounds or causeways; that of Tepejacac on the north, about three miles long, measuring from the great temple in centre of Mexico; that usually called of Iztapalapa on the south, nearly five miles in length; and that of Tacuba or Tlacopan on the west, about two miles long, likewise measuring from the temple; but at least a mile may be abstracted from each of