The besieged city received Poqomam reinforcements that were comprehensively defeated on an open field of battle, with the Spanish cavalry being decisive.

The capture of Poqomam prisoners allowed the Spanish to discover the location of a cave providing a secret entrance to 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.

[5] 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.

[6] Armed with the knowledge gained from their prisoners, Alvarado sent 40 men to cover the exit from the cave and launched another assault along the ravine from the west, in single file owing to its narrowness, with crossbowmen alternating with soldiers bearing muskets, each with a companion sheltering him from arrows and stones with a shield.

The Poqomam warriors fell back in disorder in a chaotic retreat through the city, and were hunted down by the victorious conquistadors and their Mesoamerican allies.

Those who managed to retreat down the neighbouring valley were ambushed by Spanish cavalry who had been posted to block the exit from the cave, the survivors were captured and brought back to the city.

The siege had lasted more than a month and because of the defensive strength of the city, Alvarado ordered it to be burned and moved the inhabitants to the new colonial village of Mixco.

[11] The ruins are situated at the northeastern extreme of the department of Chimaltenango within the municipality of San Martín Jilotepeque;[12] they are strung out over 1 kilometre (0.62 mi) along a 880-metre (2,890 ft) high ridge approximately 4 kilometres (2.5 mi) from the point where the Pixcaya River flows into the Motagua River, which drains into the Caribbean Sea.

[23] American archaeologist A. Ledyard Smith visited the ruins in 1949 and wrote a chapter about the site in his Archaeological Reconnaissance in Central America, published by the Carnegie Institution of Washington in 1955.

[26] The ruins consist of 15 groups containing the remains of over 120 major structures, including temples, palaces, and courts for playing the Mesoamerican ballgame.

[27] Originally the city had its main entrance on the western side, a modern road has now been cut through to the ruins from the west along a similar route.

[29] Almost all archaeological finds at the city, including both artefacts and earlier versions of later structures, date to the last few hundred years before the Spanish conquest.

[19] Traces of charcoal at the base of the old retaining wall have been radiocarbon dated to the 13th century, indicating that the expansion of Group A took place no earlier than that.

The north wall was 9.1 metres (30 ft) wide, suggesting that the earlier platform was very large and probably extended south almost as far as the ballcourt.

Replicas of the ballcourt marker have been placed in both walls; the original is in the Museo Nacional de Arqueología y Etnología in Guatemala City.

[46] Platform B5 possesses two stepped levels with cornices and encloses the northern part of the west side of the Group B plaza.

[46] It was built from stone slabs and was originally taller than the final version of the platform but was cut back to the reduced height of the new building.

[63] The East Plaza was accessed via a narrow alley that ran between a large, low platform and a high-status residential structure with a patio (C8).

A wide stucco bench was built against the rear wall and a concave hollow in the floor was probably designed for the burning of incense.

[67] In its final form the pyramid base measured 18.25 by 9.75 metres (59.9 by 32.0 ft); it had five corniced levels and only possessed a single stairway in place of the earlier two.

[67] The earliest metal artefacts in the Maya region have been dated to the Terminal Classic period (c.800-900);[69] the presence of metal artefacts associated with the earliest construction phase at Mixco Viejo (Jilotepeque Viejo) demonstrates the short span of the site and suggests that all three construction phases succeeded each other relatively rapidly.

[70] Further ceramic offerings were deposited under both of the latter two phases and an artificially deformed skull was interred under the central axis of the final version.

It faces west towards the plaza and had a single access stairway flanked by sloping balustrades that terminate in vertical sections at the upper extremes.

The second version of the pyramid was very poorly preserved; excavations uncovered many stucco fragments but were unable to determine which of the first two construction phases they belonged to.

It faces west onto the plaza and has two access stairways, both flanked by ramps built from small slabs of stone and with cornices at the top.

An offering was excavated from the central axis of the platform's base, it consisted of two ring-shaped clubs placed on either side of a stone ball.

The cave was used for ceremonial activities, related to the presence of the spring within it and the fact that the walls are formed from green phyllite; greenstone was sacred to the Maya and was associated with water and fertility.

It was artificially widened to permit access and was still used for Maya ceremonies in the late 20th century, when archaeologists found recent evidence of activity.

[29] The Postclassic Maya custom of interring the cremated remains of the deceased in urns was restricted to the elite; commoners where buried in simple tombs outside the city centre.