Meanwhile, Velasquez sent another expedition, led by Pánfilo de Narváez, to oppose Cortès, arriving in Mexico in April 1520 with 1,100 men. Cortés left 200 men in Tenochtitlan and took the rest to confront Narvaez, whom he overcame, convincing his men to join him. In Tenochtitlán one of Cortés's lieutenants committed a massacre in the Great Temple, triggering local rebellion. Cortés speedily returned, attempting the support of Moctezuma but the Aztec emperor was killed, possibly stoned by his subjects. The Spanish fled for the Tlaxcaltec during the "Noche Triste", where they managed a narrow escape while their back guard was massacred. Much of the treasure looted was lost during this panicked escape. After a battle in Otumba they reached Tlaxcala, having lost 870 men. Having prevailed with the assistance of allies and reinforcements from Cuba, Cortés besieged Tenochtitlán and captured its ruler Cuauhtémoc in August 1521. As the Aztec Empire ended he claimed the city for Spain, renaming it Mexico City.