Mesoamerican empires like that of the Aztecs were not like modern nation-states that consolidate control of the territory within their borders. Instead the Aztec Empire was a syndicate in which the Mexica, their allies, and their subordinates thrived on trade and tribute backed by the threat of force.

When a city succumbed, its captive warriors were marched to Tenochtitlan to be sacrificed. The defeated city was obligated to provide tribute to be distributed within the empire, including corn and other foods, flowers, feathers, gold, and hides. But conquest stopped short of assimilation. Rulers and nobles remained in place. Subjects were not required to adopt Mexica gods. Some children of nobles would be sent to Tenochtitlan for their education and were encouraged to intermarry with the nobles of other states within the empire, but otherwise local communities and their leaders remained intact.

The death of a ruler is always a time of uncertainty, and this was especially true in Mesoamerica under the Aztec Empire. For peoples of the Valley of Mexico and beyond, this meant war was sure to arrive. The council of high nobles who served the deceased ruler chose the new tlatoani, who was often the commander of the army. Once the new tlatoani was named, he would embark on a military campaign in order to answer the questions his succession raised: Would he bring sacrificial victims to the gods and thus ensure prosperity and fertility during his reign? Could he preserve and strengthen the alliances that composed the empire? Could he keep rivals at bay?

A success in the tlatoani’s inaugural military campaign provided new tribute-paying subjects, produced a long train of sacrificial victims captured in battle, maintained the stability of the empire’s alliances, warned off potential foes, and kept conquered areas in subordination. After the successful campaign, the new tlatoani invited the rulers of allied, subject, and enemy city-states alike to his coronation ceremony — a pageant of gifts, feasts, and bloody sacrifice that proclaimed Tenochtitlan’s might.

But success was not always possible, as the troubled rule of Tizoc (r. 1481–1486) demonstrated. His wars sometimes resulted in a greater number of casualties among his own forces than of sacrificial victims for his altars. Five years after he was crowned, he was poisoned by his own subjects. His successor, Ahuitzotl (r. 1486–1502), faced the challenge of reinvigorating the empire through renewed displays of strength. He had little margin for failure. To symbolize the restoration of Tenochtitlan’s power, he waged wars of conquest that defied precedence in their scale, culminating in two coronation ceremonies, the second of which incorporated sacrificing over eighty thousand captive warriors.

Blood sacrifice was not new to the Aztecs. For centuries Mesoamerican peoples had honored their gods this way. For instance, the cult honoring Xipe Totec, the god of spring renewal, involved two emblematic sacrifices. Priests wore the skin of a sacrificial victim to symbolize the shedding of leaves and new growth, and they greeted the arrival of spring by binding a human sacrifice to a post and shooting his body full of arrows with slits carved along their shafts. Blood channeled off the arrows and dripped to the ground, symbolizing the spring rains.

The Aztecs elevated the warrior cult as the central observance. They were the chosen people, who faced a bleak struggle to stave off the apocalypse. The Mexica believed the earth had been destroyed and re-created four times. The end of creation loomed after their age, the fifth sun. Since this apocalypse might be forestalled through divine intervention, their sacrifice could show that humans were worthy of divine intervention. If ancient deities had given their lives to save the sun, how could mortals refuse to do the same? Their service to the gods culminated on the altar of the temple to Huitzilopochtli, where priests cut into the chests of warriors with their obsidian knives to pull out their beating hearts and raise them in sacrifice to the sun.

Such sacrifice evoked the power of Aztec rulers, but the ceremony observing the end of each fifty-two-year bundle better reflected the Mexica worldview. Had humans sacrificed enough for the gods to intercede and ensure the sun would rise again? In preparation for the end, families broke their earthenware vessels, cleansed their homes, and extinguished all fires. As the new day came, priests made a fire on the chest of a living, powerful captive warrior. Noble warriors lit torches from this new fire and relayed the flame of creation into each hearth in the empire. For the next fifty-two years, all would know the fire in their hearth, like the rising of the sun itself, was the fruit of a sacred warrior sacrifice.

The need for sacrifice, as well as the glorification of the warriors who provided it through battle, was a powerful rationale for the expansion of the Aztec Empire. The role of the Aztecs’ sacrifice-based religious system is the subject of scholarly debate: Did the religious system guide imperial expansion? Or did imperial expansion guide the religious system? These views are by no means incompatible: for the Aztecs, the peoples who came under their rule, and the peoples who resisted them, the twin goals of empire building and service to the gods were inseparable.