The water was brought across the lake from a spring at Chapultepec. After a desperate conflict, the Spaniards succeeded in cutting the pipes and tearing down the noble structure on which they were laid. Still further to harass the Mexicans and to provide their own camp with food, the soldiers went out and reaped all the grain-fields within reach. Two divisions of the army approached Mexico by land, while others, commanded by Cortez, came in his brigantines.
From a lofty tower in the city of Tezcuco the Spanish leader had watched for the signal-smokes which should tell the dwellers in the valley that the siege had begun. The Aztec canoes had come out in swarms from every town and village around the lake. Iztapalapa had just been burned, and its homeless people were all in their boats. Getting in his brigantine, Cortez bore down upon this fleet, being carried along by a strong wind that was sweeping over the water at the time, and without a shot from the cannon on their decks hundreds of the smaller crafts were crushed like eggshells and the rest chased back into the canals which interlaced the City of Mexico.
An encampment on the southern causeway leading to the city was the end of the first day's work. The Indians made an attack that night, but were quickly repulsed by the brigantines. The next morning neither land nor water could be seen for the multitude that poured out of the city, "all howling as though the world had come to an end," said Cortez.
It being seen that the canoes had come from the side unprotected by the brigantines, the Indian allies were set to work to widen every sluiceway through the dykes, in order to allow these large boats to pass. Up to that time
