Tenochtitlan was an absolutely amazing city. The city was larger than any in Europe at the time and held approximately 200,000 people with some estimates as high as 350,000. Built over 100 years or so on Lake Texcoco, the city was impressively organized.
Being built on the lake meant that land platforms were created as needed in an orderly fashion leaving clean canal streets for canoe traffic and multiple bridges and paths for pedestrians. Each neighborhood was distinct and had its required services from schools to garbage collectors.
The city also had fabulous amenities befitting a great city. Huge gardens were quite popular and the city zoo and aquariums held wildlife from all over Mesoamerica. Fresh spring water flowed through several aqueducts along the three long causeways that connected the city to the north, west and south shores.
Among the beauty of Tenochtitlan was a great amount of war and death. The large central temple complex usually held daily sacrifices and many of the different gods required human sacrifices whether they be battle captives or willing victims. On either side of the main temple were the houses of the eagle and jaguar warriors, elite warrior clans who led the armies in battle.
When Hernan Cortez brought his band of around 600 soldiers to Mexico, his chief motivation was evading his superior. Many of the men’s motivations were some combination of gold, power or God. As Cortez established a base at Veracruz he left some men to guard the camp while proceeding inland, but not before destroying his fleet to prevent any insurrection from a desire to escape.
He had a force of about 3-400 men with steel armor and swords along with crossbows, primitive firearms, and a few light cannons. One of his men, Gerónimo de Aguilar, was a survivor of a shipwreck eight years’ prior and had learned many of the languages and customs.
In a series of misguided battles, the confederation of tribes known as the Tlaxcala launched several attacks against the advancing army of Cortez. In these first engagements the Spanish were faced with armies numbering in the hundreds of thousands and easily prevailed. The Aztec Macuahuitl was a viscious weapon against unarmored foes and indeed in these battles a horse was essentially decapitated but the steel armor of the Spaniards was too effective.
Counter to some popular thought, the Spanish actually fought mostly with swords and crossbows, though they had a similar devastating result. Steel swords cut right through the padded cotton armor of the natives and crossbow bolts would fly right through the light shields. When firearms were used that had a truly terrific effect with their loud bangs and smoke they truly terrified the natives.
After every battle, Cortez released prisoners with messages of peace. Finally, the Tlaxcala were willing to meet, and the two sides realized that they both sought to control the Aztecs. The Tlaxcala were one of the few independent groups left near Tenochtitlan and were often targets of new wars primarily to steal more sacrificial victims. After this alliance was formed, the king/emperor Montezuma urgently requested to see Cortez and summoned him to Tenochtitlan before any more of his enemies united against him.
The motives of Montezuma are difficult to ascertain, he clearly was afraid of the Spanish to a degree owing to their established power and strange origins, but he seems to have attempted to orchestrate an ambush as Cortez was on his way to Tenochtitlan and prepared and sent an army towards Veracruz. He seems to have truly favored an appeasement policy, giving gifts to get the Spanish to leave but also seemed ready to hit hard with his armies.
When Cortez and his men arrived at Tenochtitlan they were given a royal welcome. They were given rooms in the royal residences and given tours around the city. They made notes of the impressive causeways and the city zoo as well as the evidence of wealth and treasures everywhere.
Here though the Spanish began to become horrified by the constant and routine human sacrifices. While it is true that the Spaniards often lusted after power and riches, the witnessing of what they perceived as pure evil would have also provided future motivation to topple the empire. Not only were their sacrifices but other brutal acts such as feeding these victims to captive jaguars and outright cannibalism.
The details are uncertain, but Cortez seems to have figured out some of Montezuma’s plots to attack the Veracruz settlement and decided to hold the emperor captive. This captivity was very civil with all daily activities, including sacrifices, continuing for months, but with the Spanish cautiously monitoring things.
This standoff persisted until Cortez had to leave the city to meet a force of around 900 Spaniards tasked with arresting Cortez for disobeying the Cuban (New Spain) governor. Cortez was able to ambush skillfully and capture the commanding officer and showed his great speaking ability by convincing the 900 men to join his cause.
While Cortez was with his newly gained army, his garrison in Tenochtitlan faced dire odds. The city was at peace when Cortez left but his second in command, Pedro de Alvarado, had been invited to a traditional Aztec feast. Accounts differ but supposedly unprovoked, Alvarado blocked the exits and slaughtered all the natives at the Feast, 600 to 1,000 people mostly of the noble class were ruthlessly slaughtered and their bodies looted for jewelry.
Following this slaughter, the residents of Tenochtitlan had enough of the Spaniards and spurred by a divine proclamation that the Spanish must be expelled, they besieged the palace complex with the garrison and the captive Montezuma.
Cortez had secured his army and had gained more local allies but was now faced with the prospect of losing his entire city garrison, his captive Montezuma and his foothold in the city. Cortez had to figure out how to regain his hold on the 200,000 people in the city while saving the few hundred they were trying to capture and sacrifice. Reports from the besieged Spanish maintained that the Aztecs would shout threats such as, “you will be sacrificed” and “we will eat you”. Every day of this would have been agonizing for the Spanish, knowing full well that capture meant certain and brutal death.