Cortez mustered his men, and found that he had eighty-seven horse; eight hundred and eighteen foot, of which one hundred and eighteen were musketeers or crossbow men; three large iron field pieces, and fifteen light brass guns. Three hundred of the men were told off to man the ships.
The Indian confederates arrived punctually: fifty thousand Tlascalans, and a vast number of levies from the other tribes.
The army was divided into three corps. One was to take up its post, under Alvarado, at Tlacopan. Another, under Olid, was to aid in capturing the causeway; while Sandoval had command of the third, whose movements were to be determined by circumstances. Cortez himself took charge of the fleet.
A quarrel arose between a Spanish soldier and a Tlascalan chief, who was a relation of Xicotencatl; who at once left the army, and started for Tlascala. He had always been bitterly hostile to the Spaniards; and Cortez saw that, unless the movement was stopped, it might become very serious. He sent a party of natives after him, with instructions to prevail upon him, if possible, to return. He refused to do so. Cortez dispatched a body of cavalry in pursuit, arrested him in Tlascala, brought him down to Tezcuco, and there hung him in the sight of his own countrymen.
The divisions of Alvarado and Olid met with no resistance in establishing themselves at Tlacopan. They cut the reservoir that supplied the city with fresh water, the great lake being salt. The next day the two divisions marched on to the causeway to make themselves masters, if possible, of the first bridge.
The natives pursued their former tactics, desperately defending barricades thrown across the causeway, and attacking the invaders with a crowd of missiles from canoes. After a long and obstinate fight, the Spaniards and their allies were obliged to fall back, with considerable loss; and Olid drew off with his division to his station commanding the other causeway.
Iztapalapan having been again occupied by the enemy, Sandoval's division attacked them by land; while Cortez, with his fleet, lay off the shore. After capturing the town, Cortez turned his attention to the canoes of the natives, which darkened the surface of the lake. At this moment a fresh breeze sprang up; and the ships, spreading their canvas, dashed amongst the canoes, overturning and destroying great numbers; while the cannon tore others to pieces, with discharges of bullets; and comparatively few succeeded in regaining the city.
It was now getting nearly dark, and the fleet coasted along the great southern causeway to the fort of Xoloc, where another branch of the causeway joined the main dike.
The fort was feebly garrisoned. Cortez landed his soldiers and carried it by storm. Here he established his headquarters, landing some of the cannon from the ships to strengthen the position.
He was now within half a league of the city, and two out of the three great approaches were already in his hands. Night and day the natives attacked the garrison; but the ships, and the guns in positions, repulsed their assaults.