As you’d guess from the titles, C. S. Forester’s Commodore Hornblower and Lord Hornblower tell the further adventures of Horatio Hornblower as he ascends in rank and importance.
The books are still full of all the naval derring-do that you’d expect from the earlier ones, but there’s also a satisfying amount of progress. The concerns of Commodore Hornblower are not those of Captain Hornblower. There are larger matters to deal with here than the command of a single ship, and he’s no longer as young as he was. It’s a difficult task to change the nature of a series of books while still maintaining its appeal, but Forester does it handily.
For some reason, I’d always had this idea that the Hornblower books were pulpy “men’s fiction,” full of high adventure and derring-do, but little else. This isn’t at all the case, as the books are superb with characterization (Hornblower alone has more depth and complexity than the entire cast of an Honor Harrington novel) and posessed of what might pretentiously be called insight into the human condition. These are real books of quality, and shouldn’t be just dismissed just because they’re compellingly readable.