Before 1794, Master and Commander was the title of an officer in the British Royal Navy who had the same rank as a Lieutenant but was treated like an intermediate between a Captain and a Lieutenant.

From 1794, this position was filled by the newly-created rank of Commander. An officer of this rank usually commanded a ship-of-war smaller than a post-ship (under 20 guns), such as a sloop-of-war or bomb-vessel, but larger than the little vessels commanded by a Lieutenant.

An officer could obtain the rank of Commander only by receiving such a Command from the Admiralty, the administrative department superintending the Navy and directed by the Lord Admiral. It was not until 1827 that an officer could have the rank of Commander without commanding such a vessel. At that time the position of First Lieutenant in a Ship of the Line was made a Commander's job.

--A Sea of Words, a Lexicon and Companion for Patrick O'Brian's Seafaring Tales, Dean King with John B Hattendorf and J. Worth Estes, Henry Holt and Company, 1995.

Master and Commander is the title of the first volume in a series of twenty by author Patrick O'Brian about the exploits of "Lucky" Jack Aubrey and his best friend, Dr. Stephen Maturin, ship's surgeon, naturalist, freedom fighter, and spy. Set in and around the British Royal Navy during the Napoleonic Wars, O'Brian's Aubrey-Maturin series is distinguished by its scholarship, attention to period detail, and psychological acuity.

O'Brian wrote the books between 1970 and 2000, and when he died at the age of 86, he was working on installment number twenty-one.

The complex wartime relationship between the characters of Aubrey and Maturin, at sea and on land, revealed chronologically and in greater and greater depth as the two men age, is one of the great achievements in 20th Century English Literature.

The books should be read in the order in which they were published, for characters come and go throughout, just as in real life, and the "ah ha!" experience of meeting someone you hadn't thought about in a while is delightful.

"The best historical novels ever written."
--Richard Snow, The New York Times