Relentless Pursuit, Paperback/Alexander Kent

As captain of His Majesty's frigate Unrivalled of forty-six guns, Adam Bolitho is required to assist the senior officer of the patrolling squadron. But all efforts of the patrols to curb a flourishing trade in human life are hampered by unsuitable ships, and by the belligerence of the Dey of Algiers, which threatens to ignite a full-scale war.