If you like Patrick O'Brien's Aubrey/Maturin books you may wish to check out the RCN series by David Drake. The setting is quite different, but the feel of the books is very similar. Drake's plots are very strongly informed by real history (usually classical Roman & Greek, rather than Napoleonic). Whether the writing is as good, worse, or better than O'Brien I leave as a question for the student.
The first two books are
With The Lightnings and
Lt. Leary Commanding both available free (as in "no-charge") and DRM-free in multiple formats from the Baen Free Library.
Xenophon