The painting displayed, the seventh in the series, depicts the conquest of Tenochtitlán (now the site of Mexico City).
The battle between the Spanish under Cortés and the Mexica under the last Aztec leader Cuauhtémoc is more properly called a siege. It began in May of 1521 and lasted into August. With newly built ships, the Spanish controlled the lake surrounding the island and blockaded the city.
Ultimately Cortés ordered the complete destruction of Tenochtitlán, including its palaces, temples, and squares. This painting attempts to distill the excitement, bloodshed, and drama of the siege into a single moment. Cortés leads his Spanish armies across one of the causeways and into the city. The captains of the other parts of his army also lead their troops towards the center of the city and the main temple compound. The Mexica put up a spirited and skilled resistance, but by August the death of much of the population, as well as months of scarce food and water, meant that they could no longer defend the city. The surrender of the survivors, the destruction of the main temple, and the capture of Cuauhtémoc marked both the end of the battle for Tenochtitlán and the end of Aztec empire.