Sharpe's Trafalgar by Bernard Cornwell
The seventeenth Sharpe novel sees Sharpe returning from India to London to join the newly formed Green Jackets in Britain. His voyage home should be a period of rest, but his ship is riven with treachery and threatened by the Revenant, a French sea-raider that is terrorising British shipping in the Indian Ocean. Betrayed and defeated, Sharpe is imprisoned on the Ile de France, doomed to rot there until the war ends. But an unlikey ally secures his escape into a British warship that is hunting the Revenant. That hunt turns into a pursuit as the French ship races home, and when she encounters the combined French and Spanish fleets of Cadiz, it seems Sharpe's enemies are safe. But over the horizon is another fleet, led by Nelson, and Sharpe's revenge will come when the two armadas meet on a calm October day off Cape Trafalgar.