Raiders of the Seven Seas - Sidney Salkow

Barbarossa, a pirate, frees a group of Spanish prisoners and makes them his crew. On a raid, he takes as a prize a Spanish countess, Alida. He has fallen in love with her by the time he arranges for her ransom by the officer who was to marry her. Exposing her intended as a coward and a liar, he goes to ask for her hand but she has escaped, and Barbarossa thinks she is the one who killed his aide, Peg-Leg.