10 Reasons for the Fall of the Aztecs

The Aztecs were fierce people who fought to kill, but they also took many prisoners as human sacrifices to celebrate their victory. Most Aztec warriors fought one-on-one, using wooden swords embedded with rows of sharpened volcanic glass or obsidian and spears. 

Spanish conquistador Hernándo Cortés reached the area in 1519 and was impressed by the grandeur of the Aztec Empire. However, while impressive to look at, it hid the fact that the Aztec Empire had a weakness, as many city-states in the area were resentful of the Aztecs. 

Cortés spent a year of warfare, intrigue, and deal-making to form a vast army. Finally, in 1521, they assaulted the city, and after 85 days of fierce fighting, the Spanish conquistadors brought the mighty Aztecs down. But the fall of the Aztec Empire was not only due to the conquistadors but also to several factors listed below.


The Aztecs’ view of life and the afterlife is very different from the perspectives of modern people. Their religion largely influenced their outlook and imbued within every aspect of their life. When the Spanish conquistadors first came to Aztec land, the ancient locals believed that Hernán Cortés was a direct reincarnation of Quetzalcoatl, one of the most revered gods of the Aztecs. Thus, they gladly welcomed the guests, not knowing that the Spanish had come to conquer. Because they were unopposed when they first arrived, the Europeans gained a tactical advantage when the battles started.

Human Sacrifice

The Aztecs usually carried out the human sacrifice, which some historians estimate to be 20,000 each year. They became renowned for their conduct of human sacrifices because they did it spectacularly. The Aztecs chose the people they would sacrifice in various ways. For example, some Aztecs volunteered for their community. The other people they sacrificed were soldiers and enslaved people they captured when they fought with their neighbors, while others were from their tribe. They believed that offering the heart and blood to sun god Huitzilopochtli appeased him. Likewise, they used the ritual to intimidate their enemies, lessen the effects of disastrous events, and honor important dates.


The conquistadors were the people who traveled with Cortés to Mexico. They were men from Spain who had no career or family. Therefore, they did not have to return to Spain alive. Their motivation for joining the conquest was to become rich. With that kind of motivation, they turned into vicious fighters who had no empathy for the soldiers and families they killed. These conquistadors were greedy and cruel. They burned villages, raped women, destroyed, stole, and tricked people as they searched for gold and fame. Because they were Christians, they did not respect people who did not revere Christian gods. They thought the locals had no souls; thus, it was not immoral to destroy them.

Spanish Army Tactics

The Spanish army’s tactics were different from what the Aztecs knew. The Spanish were experienced since they just came from a war with Italy, and they used flexible and modern approaches. They separated their armies into various regiments, and each unit could work independently but could also provide support to other divisions. Their battle plan was flexible, and they could change it before or during their field encounters. Moreover, they had better weapons such as guns and cannons. They also wore metal armor. They had a few horses, which the Aztecs never saw before, which improved their mobility. On the other hand, the Aztecs used spears, bows, bladed clubs, and wooden shields covered with animal hides.

Aztec Army Tactics

While the Aztecs’ battle tactics were rooted in their beliefs in rituals and magic, they did have some battle plans. The battle typically starts when the Aztec king beats on the drum, signaling the experienced or elite warriors to advance. The rest of the warriors would then follow the advance party. The young and older warriors form the third layer. Aztec warriors would use spears, darts, slingshots, and arrows. Their usual battle plan is to shift the advancing party. The first contingent would move to the back to allow the second contingent to fight. When they get tired, the third layer moves to the front. The shifting continues until one tribe wins. What hindered the Aztecs was their obsession with taking prisoners alive, which they would later feed to their gods. Thus, their victories were long and arduous, when they could easily win a battle by killing their enemies.


The Aztecs were not used to seeing larger animals as they only encountered jaguars and deer. Thus, when the Spanish army brought its cavalry division of horse-mounted soldiers, they frightened the Aztecs. The horses had the strength, power, and speed they had not witnessed before. There were suggestions that the Aztecs believed that horses were gods. The power of the horses and the Europeans who sat on top of them made the Aztecs believe that they were mighty. The fear they had contributed to their defeat, assuming they did not have the right or ability to win over what they thought was an army consisting of gods. Likewise, the horses gave the conquerors mobility, a distinct advantage as the Aztecs moved on foot. Of course, horses can carry more ammunition and other supplies, and can pull the heavy cannons as they charge. On the other hand, people on foot cannot outrun a horse.


The Aztecs did not have immunity to Western diseases. When the Spanish came, they brought a deadly weapon—smallpox, which came from the enslaved Africans they brought with them. Because they had never encountered the disease, they did not know how to treat it. Whole families died of the illness. Some that survived were left disabled, deformed, scarred, or blind. The death rate rose rapidly, and they did not have time to bury the dead; thus, they demolished the houses, including the bodies. Smallpox devastated the Aztec army, affecting their food supply and killing many of their soldiers. Many people became sick, which significantly reduced farming activities, leaving the majority of the population weak, hungry, or ill. But new discoveries also attributed the fall of the Aztecs to food poisoning, caused by salmonella from the food that the Europeans brought with them. The scientists estimate that the outbreak occurred in 1545 and persisted for five years. 

Local Enemies

The Aztecs formed many alliances to increase their wealth and strength. But they also became warriors and mercenaries for other tribes, which many neighboring tribes resented. While they thought that they were powerful, the fact is, there was a much stronger group, the Tepanec, which used the Aztecs to do their bidding. Thus, they made many local enemies. The Aztecs also created many enemies from the different states because of their propensity to take slaves and warriors as prisoners and use them as human sacrifices. The Spanish explored the animosity by forming alliances with some of these rival groups, such as the Texlacans, with whom they had an ongoing violent conflict. The associations the Spanish built with the locals increased their number and gave them inside knowledge of the Aztecs’ battle plans.

Political Crises

The Aztec Empire expanded because it was able to conquer neighboring cities. But it came at a cost. Its military gained power in numbers because it added men provided by conquered and allied states. Thus, they could defeat most of their rivals and gain additional territories. However, they demanded tribute from the defeated states and took captives that they used as human offerings to their gods with each victory. The Aztec religion believed that the gods gave them life, so it is fitting to repay the gift with human sacrifice (often heart and blood). Their rituals angered neighboring and rival tribes. There were constant rebellions, which caused instability that made the empire crack. These rival tribes formed alliances with the conquistadors.

Technological Disadvantage

If you go by the numbers, the Aztecs outnumbered the Spanish conquistadors. Cortés only had 800 conquistadors with him. However, with several alliances he built for a year, he gained tens of thousands of local warriors, ready to fight the hated Aztecs. But what brought the Aztecs down were the weapons the Europeans used. Although they were still crude, they were still unmatched by the primitive weapons of the Aztecs. Their armor alone consisted of layers of metal. They had cannons and guns, and they rode horses for mobility. The fierce Aztec warriors might have a fair playing field when fighting with other states, but their wooden shields covered in animal hides and their bladed clubs, spears, and bows were no match for the Europeans’ guns, let alone the cannons.

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