Prescott wrote three other books on the Spanish Empire. The first, "The History of the Conquest of Mexico", was written between 1838 and 1842 and published in 1843. It is thought to be one of the most important books written on ancient Mesoamerica. It was so popular at the time that John Y. Mason, the United States Secretary of the Navy had a copy placed in the library of every fighting ship. Today, it is still the best known and most popular work by Prescott. The "Conquest of Mexico" was followed by the "Conquest of Peru", which was written between 1843 and 1847, and published in March 1847. It was similarly successful. Prescott's last book, the "History of the Reign of Phillip II" was never finished and is not thought to be of the same quality as his other works. Prescott started work on it in 1842, but stopped in 1858 after suffering a stroke. 