Day after day the same tactics were repeated, the Mexicans every night repairing the breaches cleared out every day by the Spanish allies. Cortez found it impossible to guard the causeway and prevent this, the soldiers being already overcome by the fatigue of their daily encounters. Alvarado's division, however, held at night the ground they won in the daytime; but the troops suffered dreadfully from the incessant toil, and from the rain, which poured down in torrents. The soldiers of Cortez fared little better, for the buildings in the fort of Xoloc afforded shelter but to few; and the rest had to sleep on the causeway in its rear, exposed to all the tempestuous weather.

Frequently, too, they were called up to battle; for the Aztec emperor, contrary to the usual practice of his countrymen, frequently attacked by night; often making simultaneous attacks on the three divisions on the causeways, while at the same moment troops from the neighboring towns attacked their camps in the rear. He did not content himself with open attacks, but resorted to stratagem. On one occasion he had a large number of canoes in ambuscade, among some tall reeds bordering the lake. Several large boats then rowed near the Spanish vessels. Believing that they were filled with provisions intended for the city, two of the smaller vessels pursued them. The Aztec boats made for the reeds, the Spaniards followed, and presently struck upon submerged timbers the Indians had driven in. They were instantly attacked by the whole fleet of canoes, most of the men were wounded, and several, including the two captains, slain, and one of the Spanish craft captured.

It was now three months since the siege had begun, and the attitude of the Mexicans was as bold and defiant as ever. Several attempts which Cortez had made to open negotiations with the young emperor had been received with scorn. It was certain that, sooner or later, famine would do its work; for the approaches to the city were all in the hands of the Spaniards, and as the towns of the lake were either friendly or overawed by the great army of their allies, even the canoes, which at first made their way in at night with provisions, had ceased to steal across in the darkness. The great native levies were of little use to the Spaniards in the absolute fighting, but they did good service by overawing the towns, making expeditions against the tribes that had not yet consented to throw in their lot with the invaders, and by sweeping in provisions from a wide extent of country.

But to wait until famine did its work little suited the spirit of the Spaniards. The process would assuredly be a long one, for men who fought so stoutly would resist starvation with equal tenacity; besides, the duration of the siege was already beginning to excite discontent among the allies, whose wars were generally of very short duration. The Spaniards, too, were suffering from severe illness brought on by fatigue, exposure, and hardship.

It was now determined to make a grand effort to obtain possession of the great market of Tlatelolco, which lay on the northwestern part of the city. Its possession would enable the force of Cortez to join hands with those of Alvarado and Sandoval; and the spacious market itself, with its halls and porticoes, would furnish accommodation for the army; and enable them to attack the city at close quarters, instead of having to fight their way, every day, along the causeway.

Sandoval was to join Alvarado, sending seventy picked troops to support Cortez. Advancing along the causeway, and supported not only by the ships, but by a countless host of canoes filled with the allies of the lake cities, who penetrated the canals, and caused confusion in the rear of the Aztecs, the division of Cortez cleared the suburbs of their opponents, and then advanced towards the square of Tlatelolco by three great streets.

Alderete commanded the force that advanced by the main central avenue. This was a raised causeway, with canals running on either side of the road. Tapia and a brother of Alvarado commanded one of the other columns, while Cortez led the third. A small body of cavalry, with three guns, remained in reserve in the great street leading to the causeway; and here the column were to rally, in case of disaster.

The three columns advanced simultaneously. The Spanish pressed the Aztecs back before them. Their allies filled up the canals as they took them, one by one. The Tlascalans stormed the houses, and attacked the enemy on their roofs; while the canoes engaged those of the Aztecs, and so prevented them from interfering with the men occupied in filling up the breaches. The parallel streets were near enough to each other for the Spaniards to hear the shouts of their companions in the other columns, and to know that all were gaining ground steadily.

The enemy in the streets fought with less obstinacy than usual; and Cortez, with his usual keen-sightedness, at once apprehended that the feebleness of the resistance indicated some device, and that the Aztecs were allowing them to advance, only to lead them into a trap.

He had received a message from Alderete saying that he was getting on fast, and that he was but a short distance from the great square. Fearing that this officer, eager to be the first to gain the marketplace, was not taking proper precautions to secure his retreat; Cortez, with a small body of troops, retraced his steps, and turned up the street by which Alderete's column had advanced. He had gone but a short distance, when he saw that his stringent orders had been neglected; for he came upon an opening some thirty feet wide, full of water at least twelve feet deep. A slight attempt, only, had been made to stop the gap; and stones and timber, lying by the side, showed that it had been abandoned as soon as commenced.