Acamapitzin was followed in 1396 by Uitziliuitl, and he in 1417 by Chimalpopoca, Tlacateotl having succeeded to the rulership of Tlaltelolco in 1406. Meanwhile Techotlala had died, and Ixtlilxochitl had become ruler of Tezcoco about 1400. The Mendoza codex assigns the conquest of certain cities to these kings, but it is probable that in these expeditions they acted merely as allies of Tezcoco or Azcapotzalco. During this period the power of Azcapotzalco began to expand, and, aided by the Mexicans, Tezozomoc, the ruler of that city, attacked Ixtlilxochitl of Tezcoco. The obstinate war which followed was the commencement of the struggle between the Tepanec and Acolhua for the hegemony of the valley, but for the time the latter prevailed, and a hollow peace was made. This lasted but a short time, and Ixtlilxochitl was eventually killed in an ambuscade by the Tepanec, who had utilized the interval in winning over certain of his allies. The Tepanec thus became masters of Tezcoco in 1418, and Nezahualcoyotl, the legitimate heir, was driven into exile. Tezozomoc, the Tepanec ruler, did not however enjoy his success long, but died about 1425 at an advanced age. So old was he, it is related, that he was at last kept in a basket surrounded with wool for warmth, and his final years were embittered by dreams that Nezahualcoyotl in the form of an eagle devoured his heart, or, as a lion, sucked his blood. His death brought internal dissension upon Azcapotzalco; one of his younger sons, by name Maxtla, assassinated the heir-designate and seized the power. He seems to have been the most energetic of the members of the ruling house, but lacked his father’s political wariness, since he began to quarrel with Mexico. This was a fatal mistake, since it caused the Aztec, secretly at first, to intrigue with the exiled Nezahualcoyotl, who had, moreover, many friends among the cities where the Acolhuan element was strong. In 1417 Itzcoatl succeeded to power in Tenochtitlan; the Aztec had by this time increased considerably in numbers and prosperity, and the new ruler proved himself a man of action and an excellent general. He definitely espoused the cause of the exile, with the result that the latter, aided by the people of Tlaxcala and Uexotzinco, succeeded in recapturing Tezcoco and killing every Tepanec in the city. At the same time Coatlichan was stormed by the Chalca, who had also offered assistance to Nezahualcoyotl. These events brought matters to a head; Maxtla, refusing peace, rashly sent an expedition against Tenochtitlan, and the populace in terror wished to submit. But Itzcoatl succeeded in inspiring them with courage, and, aided by Quauhtlatoa, who had just been elected to the kingship of Tlaltelolco, they inflicted a signal defeat upon the invading force. Nor was this all, Itzcoatl followed up his success by attacking Azcapotzalco, which was successfully stormed and Maxtla was killed. Meanwhile the forces of Tlaxcala and Uexotzinco