The Mauritius Command — Patrick O'Brian

Captain Jack Aubrey is ashore on half pay without a command--until Stephen Maturin arrives with secret orders for Aubrey to take a frigate to the Cape of Good Hope under a commodore's pennant, there to mount an expedition against the French-held islands of Mauritius and La Reunion. 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 pushes his crew to the verge of mutiny.