But a copy of the text surfaced at an auction in London in 2003 when it was bought by enthusiasts.
Forester wrote 11 books about fictional Royal Navy officer Hornblower.
His character was played by Gregory Peck in the 1951 movie Captain Horatio Hornblower RN and by Welsh actor Ioan Gruffudd in a series of films for ITV.
Forester - real name Cecil Louis Troughton Smith - died in 1966 aged 66.
The author, who moved to the US during World War II, also wrote novels including The African Queen and The General.
Full story at BBC.