Alfred Thayer Mahan was one of the most prominent naval theorists of the late 19th century, in effect to sea warfare what Clausewitz was to land warfare. He was the son of Dennis Hart Mahan who taught military history and tactics at West Point for nearly half a century up to about 1870. AT Mahan was a US naval officer who reached the rank of captain although he never particularly liked going to sea. He was a good historian for his time and his books, particularly the one quoted in this thread, had a tremendous effect on the RN and USN, and most western navies and, of course, the IJN. He was actually more admired perhaps in Britain than in the USA. Mahan was a proponent of the "blue water" school of naval thought, best exemplified by the RN in the 19th century. He did not believe, or perhaps did not understand the "guerre de course," as preached by the French naval theorists of the "jeune ecole" school which emphasized attacking merchant shipping rather than enemy warships.
Mahan wrote several books including a history of the War of 1812 and I believe that his theory of "the fleet in being," -- that a fleet by its very existence poses a threat, whether or not it is used, as it ties down enemy naval forces, derives from the situation on Lake Ontario in 1813-1814.