With Cortez in Mexico, or By Right of Conquest - G. A. Henty

In perhaps the most audacious military enterprise in the history of human conquest, Cortez, with only a few hundred men, conquered a civilization of tens of thousands. This is the story of an Englishman who boards a merchant ship destined for the New World, but a shipwreck strands him in Pre-Columbian Mexico, and Roger must find a way to avoid becoming one of the many human sacrifices offered to the Aztec gods.