The Mauritius Command by Patrick O'Brian
Patrick O'Brian's Aubrey-Maturin tales are now widely acknowledged to be the greatest series of historical novels ever written. All eighteen books are being re-issued in hardback by HarperCollins with stunning new jackets.
Captain Jack Aubrey is ashore on half-pay without a command - until his friend, and occasional intelligence agent, Stephen Maturin, arrives with secret orders for Aubrey to take a frigate to the Cape of Good Hope, under a Commodore's pennant.
But the difficulties of carrying out his orders are compounded by two of his own captains - Lord Clonfert, a pleasure-seeking dilettante, and Captain Corbett, whose severity can push his crews to the verge of mutiny.