In 1525 Pedro de Alvarado sent a small company to conquer Mixco Viejo (Chinautla Viejo), the capital of the Poqomam. At the Spanish approach, the inhabitants remained enclosed in the fortified city. The Spanish attempted an approach from the west through a narrow pass but were forced back with heavy losses. Alvarado himself launched the second assault with 200 Tlaxcalan allies but was also beaten back. The Poqomam then received reinforcements, possibly from Chinautla, and the two armies clashed on open ground outside of the city. The battle was chaotic and lasted for most of the day but was finally decided by the Spanish cavalry, forcing the Poqomam reinforcements to withdraw. The leaders of the reinforcements surrendered to the Spanish three days after their retreat and revealed that the city had a secret entrance in the form of a cave leading up from a nearby river, allowing the inhabitants to come and go.