Captain Blood. by Rafael Sabatini

Peter Blood, with experience as a soldier and sailor, is practicing medicine in Bridgewater, England, when he inadvertently gets caught up in a rebellion being waged by the Duke of Monmouth. After being convicted of treason, Blood and some of the rebels are sentenced to slavery in the Caribbean. The year is 1688. During the course of Blood's servitude, he works on the sugar plantation of Colonel Bishop and becomes infatuated with the colonel's niece, Arabella.
When Bishop realizes that Blood is an accomplished physician he "employs" Blood in that capacity. When the colony is attacked by a Spanish force, Blood and some of the other slaves manage to escape and take over the Spanish ship. Several of the other escapees turn out to be experienced seaman, including as officers in the British navy. This group turns the Spanish ship into a very successful pirate ship, specializing in raiding Spanish shipping.
This begins Captain Blood's journey toward redemption and his "courtship" of Arabella. Sabatini based Blood's character on several historical figures, including a doctor who was sentenced to slavery (but did not become a pirate), as well as Henry Morgan (who was a pirate). His most well known novel was Scaramouche. Sabatini also wrote a number of short stories about Captain Blood in the early 1920s.