My copy's a hardback published in 1940; my parents bought several boxes of old books at auction, and this was one that I pulled out. In more modern editions it's entitled "Beat To Quarters", which makes slightly more sense given the storyline.
The first book to be written in the Hornblower series, although not the first book chronologically. Having looked around for more information on the series after reading this, most people suggested reading them in the order they're written.