What was the powerful Aztec Triple Alliance?

The creation of the Aztec Triple Alliance followed the fall of the powerful Tepanec Empire.

By the early 15th century, the Tepanec ruler Maxtla had alienated many subject city-states through his overbearing rule and repeated assassinations of rival leaders.

Tenochtitlan, one of the Tepanecs’ tributary cities, began to grow in strength under the leadership of Itzcoatl, who had become tlatoani (ruler) in 1427.

With the support of his chief adviser, Tlacaelel, Itzcoatl aimed to free Tenochtitlan from Tepanec domination. 

Texcoco was another unhappy city-state. Years earlier, its leader, Nezahualcoyotl’s father, had been killed due to Maxtla’s violence.

By 1428, Nezahualcoyotl returned from exile with support from Tenochtitlan and contributed troops to a joint military revolt.

Tlacopan also agreed to join the rebellion after the allies held a series of negotiations.

This smaller Tepanec city shared a border with Tenochtitlan. United by shared complaints and aims, the three cities attacked Azcapotzalco, the Tepanec capital. 

The coalition captured and destroyed Azcapotzalco after a bitter campaign that tested the strength of their alliance.

Maxtla was killed, and the Tepanec state lost control over its former empire. After the victory, Tenochtitlan, Texcoco, and Tlacopan formalised their cooperation into a permanent alliance.

They divided tribute from conquered towns between themselves, and they granted Tenochtitlan and Texcoco two shares each, while Tlacopan received one.

A formal agreement outlined how each city would rule its own affairs, take part in joint military campaigns, and share the spoils of war.

Totoquihuaztli I, the ruler of Tlacopan, played the most important role because he brought Tepanec support into the coalition. 

In the years that followed, Itzcoatl (r. 1427–1440) and Nezahualcoyotl used the alliance to tighten control at home and to push outward.

Tlacaelel pushed for a political reform that glorified the Mexica people of Tenochtitlan and rewrote their history and built temples.

As a result, their city became the religious and cultural centre of the alliance.

Aztec military campaigns after 1430 targeted city-states throughout the Valley of Mexico and nearby regions.

The alliance’s armies conquered key rivals such as Xochimilco (1430), Chalco (1465), and Mixquic.

In each case, conquered cities were forced to pay regular tribute in goods such as maize, cotton, cacao, obsidian, and exotic feathers.

Tribute lists recorded in codices show that, at its height, the empire controlled over 370 tribute-paying provinces.

The system became highly organised, with tribute collectors known as calpixque, porters called tameme, and an extensive network of roads and warehouses that ensured steady delivery to Tenochtitlan. 

Tenochtitlan quickly overshadowed its partners in military and political matters.

Its location on Lake Texcoco allowed it to control trade routes and send out armies across the central plateau.

Under rulers such as Moctezuma I (r. 1440–1469) and Ahuitzotl (r. 1486–1502), the city pushed far into Oaxaca, Guerrero, and the Gulf Coast.

As the alliance expanded, the tlatoani of Tenochtitlan took the lead in imperial campaigns and ran major building projects such as the Templo Mayor. 

Texcoco maintained its reputation for culture and learning under Nezahualcoyotl and, later, under his son Nezahualpilli.

Texcocan nobles wrote poetry, collected law codes, and studied astronomy.

Nezahualcoyotl himself gained fame for his philosophical poetry and leadership.

The city kept a royal library and botanical gardens that showed its role as a centre of learning.

It also provided experienced judges, priests, and administrators to the alliance’s government.

In contrast, Tlacopan stayed less prominent, but it continued to share in tribute and to participate in major campaigns. 

As the empire expanded, the alliance began the Flower Wars, which were ritual battles against neighbouring states such as Tlaxcala and Huexotzinco.

These conflicts fulfilled multiple purposes: they trained warriors, provided captives for sacrifice, and built the alliance’s military reputation.

Fought at agreed locations and often set in advance, the battles gave Aztec warriors opportunities to earn battlefield honours.

Aztec codices and Spanish accounts described the importance of sacrifice as a way to maintain cosmic order and to please the gods during major festivals such as Tlacaxipehualiztli. 

In 1519, Hernán Cortés landed on the Gulf Coast with a small Spanish force and a network of Indigenous allies.

Among his most important allies were the Tlaxcalans, who had resisted Aztec rule for decades.

Cortés marched inland and took Moctezuma II (r. 1502–1520) hostage in Tenochtitlan by late 1519.

Spanish presence and Moctezuma’s passive leadership caused unrest in the capital. 

In May 1520, the alliance split when a rebellion broke out during a religious festival.

Spanish troops killed hundreds of unarmed participants in what became known as the Massacre at the Templo Mayor.

Tenochtitlan broke out in violence, and Moctezuma died soon after, either from wounds or at the hands of his own people.

The Spanish retreated from the city during La Noche Triste, and they suffered heavy losses. 

Cuauhtémoc, Moctezuma’s nephew, became the new tlatoani and led the defence of Tenochtitlan.

Unfortunately, the alliance broke down, and its members no longer acted together in defence of the capital.

Texcoco, under Ixtlilxochitl II, switched sides and joined Cortés, offering troops and local knowledge.

Tlacopan contributed little to the final defence, so Tenochtitlan fought alone, surrounded by water and cut off from food and supplies. 

In August 1521, the city finally fell after a siege that lasted three months.

Thousands died from hunger and disease during the battle. Tenochtitlan lay in ruins, and the empire collapsed.

At its peak, the city may have had a population of 200,000. Spanish accounts and Nahua sources described the scale of destruction.

On the ruins of the capital, Cortés founded Mexico City and was appointed Governor and Captain General of New Spain.

The Aztec Triple Alliance ceased to exist, and Spanish authorities quickly set up colonial rule in the former empire’s heartland.