An afterthought to my post above, re. the officer on whom Hornblower might have been based:

C.S. Forester wrote a fairly good naval history of the Anglo-American War of 1812; it borrowed heavily from Teddy Roosevelt's book on the same subject but added a few notes and opnions from the British side.

He covered the naval operations in the Chesapeake quite well, and described Commodore Gordon's expedition up the Potomac. (Note that the name was just Gordon, not Gordon Stewart; I may have been confusing him with the American Captain Charles Stewart, who had to flee for dear life with the USS "Constellation" in 1813 near Washington, but who later commanded the USS "Constitution", and captured HMS "Cyane" and HMS "Levant" in a battle towards the end of the war).

Apparently, Gordon had served in Central America in 1808-1809(as did Hornblower) and at Riga in Russia, in 1812 (as did Hornblower) before going to the Chesapeake. There are a few other parallels between the real-life and fictional Captains.

Forester frequently mixed real and fictional characters together in the same setting; Sir Edward Pellew (later Lord Exmouth) was a real and very famous historical figure.