Wikipedia
Post Captain is the second historical novel in the Aubrey–Maturin series by Patrick O'Brian, first published in 1972. It features the characters of Captain Jack Aubrey and naval surgeon Stephen Maturin in the early 19th century and is set in the Napoleonic Wars.
During the brief Peace of Amiens, Aubrey and Maturin live in a country house allowing both of them to meet the women they eventually will marry. Then their life is turned upside down when Aubrey loses his money due to decisions of the prize court and a dishonest prize-agent. When the war begins afresh, Aubrey has a command, seeing action while gaining fewer prizes yet succeeding in his military goals. The emotions of his love life interfere with his ways at sea.
The novel was received well at its initial publishing, but received more and better notice after its re-issue in 1990. That much of the story is set on land drew some to consider it O'Brian's homage to Jane Austen, one of his favorite authors.
Usage examples of "post captain".
I have a feeling that the Marchesa will try to persuade Mr Prater that a post captain should always wear a dress sword suspended from slings on the waistband of the breeches.