He isolated the island and occupied it for 90 days
Explanation:
In May 1521, one of the longest unbroken battles in history began, lasting almost 90 days. The Spaniards, with their broad coalition, launched an attack on Tenochtitlan itself - the center of the Aztec Empire.
Cuauhtemoc ordered the general mobilization of the people, not just the military classes, and even women took up arms to defend their city. The goals were clear; After it has been eliminated the possibility of surrender, the struggle for bare life, for every street, house and canal, was launched.
The great advantage on the side of the Spaniards and their coalition was the superior technology, which this time manifested itself in ships that very quickly became the absolute rulers of Lake Texcoco. With them, Tenochtitlán became a cut off island, with insufficient supplies of food and water. The losses on both sides were enormous, and after a while Cortés shifted most of the war burden to Tlaxcalane. Although he spared his men in this way, he found himself in an unenviable position as far as progression goes because the Tlaxcalans were far weaker than the Aztecs.
Also, during the war years a bunch of Spanish weapons came into the hands of the Aztecs, so now many of their warriors also had swords and steel blades on top of their spears. In addition, cannons were not much used in street fighting, while houses and barricades were designed for guerrilla warfare in which the Aztecs were masters. Rain of rocks, spears and arrows poured down every street that the Cortés men would try to advance. Due to the overall situation, establishing a permanent base within the city was extremely risky, and the only other solution for a more permanent occupation of the city was complete destruction. Every conquered house or temple was destroyed to the ground so that they would not fall into the Aztec hands again overnight. The fight for each alley lasted until June 30, when a larger attack was ordered by Cortés, which was on his own ended with a general disaster and by capturing and sacrificing more Spaniards.
Such a moral blow began to collapse the coalition, which threatened complete defeat. Instead for Cuauhtemoc to take advantage of the current moral and return it under your own the wing of other indigenous peoples, who have bowed to newcomers, but have now starting to leave, Cortés took the initiative by launching attack against one "rebel and rebel" tribes. This action has borne fruit and brought back some trust in his ranks. Since then, the Spaniards have mostly recorded success for success while at defender efficiency was constantly declining. It's all over August 13, when the last Aztec fort was destroyed in Tenochtitlan, though it was weeks before the outcome of the battle was completely clear.