Otumba (Conquest of Mexico).
Fought July 8, 1520, between 200 Spaniards, with some thousands of Tlascalan auxiliaries, under Cortes, and a force of about 200,000 Aztecs. The Spaniards, wearied by a long march on their retreat from Mexico, were intercepted by the Aztecs, and after many hours' fighting, were on the verge of defeat, when a charge of a few cavaliers, headed by Cortes, into the very heart of the Aztec army, so discouraged them that they fled in disorder. It is said that 20,000 Aztecs fell.