establish themselves as a military power. The importance of warriors and the integral nature of warfare in Mexica political and religious life helped propel them to emerge as the dominant military power, prior to the arrival of the Spanish in 1519. The new Mexica city-state allied with the city of Azcapotzalco and paid tribute to its ruler Tezozomoc. Azcapotzalco began to expand into a small tributary empire with Mexica assistance. The Mexica ruler was not recognized as a legitimate king until this point. Mexica leaders successfully petitioned one of the kings of Culhuacan to provide a daughter to marry into the Mexica line. Their son Acamapichtli was enthroned as the first of Tenochtitlan in 1372. The Tepanecs of Azcapotzalco expanded their rule with help from the Mexica, while the Acolhua city of Texcoco grew in power in the eastern portion of the lake basin. Eventually, war erupted between the two states, and the Mexica played a vital role in the conquest of Texcoco. By then, Tenochtitlan had grown into a major city and was rewarded for its loyalty to the Tepanecs by receiving Texcoco as a tributary province. Mexica warfare was marked by a focus on capturing enemies rather than killing them from its tactics to arms. Capturing enemies was important for religious ritual and provided a means by which soldiers could distinguish themselves during campaigns. Tepanec War In 1426, the Tepanec king Tezozomoc died, and the resulting succession crisis precipitated a civil war between potential successors. The Mexica supported Tezozomoc's preferred heir Tayahauh, who was initially enthroned as king. But his son Maxtla soon usurped the throne and turned against factions that opposed him, including the Mexica ruler Chimalpopoca. The latter died shortly thereafter, possibly assassinated by Maxtla. The new Mexica ruler Itzcoatl continued to defy Maxtla, and he blockaded Tenochtitlan and demanded increased tribute payments. Maxtla similarly turned against the Acolhua, and the king of Texcoco Nezahualcoyotl fled into exile. Nezahualcoyotl recruited military help from the king of Huexotzinco, and the Mexica gained the support of a dissident Tepanec city called Tlacopan. In 1427, Tenochtitlan, Texcoco, Tlacopan, and Huexotzinco went to war against Azcapotzalco, emerging victorious in 1428. After the war, Huexotzinco withdrew, and, in 1430, the three remaining cities formed a treaty now known as the Triple Alliance. The Tepanec lands were carved up among the three cities, whose leaders agreed to cooperate in future wars of