G. A. Henty 
By Right of Conquest [EPUB ebook] 
or With Cortez in Mexico

‚The conquest of Mexico, an extensive empire with a numerous and warlike population, by a mere handful of Spaniards, is one of the romances of history. Indeed, a writer of fiction would scarcely have dared to invent so improbable a story. Even the bravery of the Spaniards, and the advantage of superior arms would not have sufficed to give them the victory, had it not been that Mexico was ripe for disruption.‘