What event does cortez describe in his fifth letter?

In his fifth letter to Charles V, Hernán Cortés describes the conquest of the Aztec Empire, focusing particularly on the fall of Tenochtitlán. He recounts the siege of the city, detailing the hardships faced by both the Spanish forces and the Aztec defenders. Cortés emphasizes the bravery of his men and the strategic maneuvers that led to the eventual capture of the city, highlighting the wealth and resources he discovered there. The letter serves to inform the Spanish crown of his achievements and the potential for further conquests in New Spain.