G. A. Henty 
By Right of Conquest 

When Roger Hankshaw boards the merchant ship Swan for a perilous journey to the New World, little does the young Englishman know what adventure awaits him. After a shipwreck strands him in Pre-Columbian Mexico, Roger must find a way to avoid becoming one of the many human sacrifices offered to the Aztec gods. Proving himself to be honorable and trustworthy, Roger builds enduring friendships with many of the natives. Later, when the Spanish noble and explorer Hernando Cortez arrives, Roger is placed in a difficult position. How can an Englishman explain his presence in Mexico? Cortez, with a military force intent on converting the heathen Aztecs, will also plunder their riches. Can Roger help his native friends survive the turmoil of the Spanish conquest of Mexico?