The novels, in the order they were written:

1. The Happy Return (1937, called Beat to Quarters in the US)
2. A Ship of the Line (1938, called simply Ship of the Line in the US)
3. Flying Colours      (1938, spelled Flying Colors in some US editions)
4. The Commodore    (1945, called Commodore Hornblower in the US)
5. Lord Hornblower   (1946)
6. Mr. Midshipman Hornblower   (1950, collected short stories)
7. Lieutenant Hornblower   (1952)
8. Hornblower and the Atropos   (1953)
9. Hornblower in the West Indies   (1958, Admiral Hornblower in the West Indies in some US editions)
10. Hornblower and the Hotspur  (1962)
11. Hornblower and the Crisis     (1967, unfinished novel and short stories, Hornblower During the Crisis in some US editions)
12.  

In chronological order:

1. Mr. Midshipman Hornblower
2. Lieutenant Hornblower
3. Hornblower and the Hotspur
4. Hornblower and the Crisis
5. Hornblower and the Atropos
6. The Happy Return
7. A Ship of the Line
8. Flying Colours
9. The Commodore
10. Lord Hornblower
11. Hornblower in the West Indies