Mary Read was born in England, the daughter of the widow of a Royal Navy sea captain. After the death of her older brother Mark Read, Mary was forced to pretend to be a boy by her mother, who wanted for Read's paternal grandmother to continue financially assisting the family. Read found work as a foot-boy and later found employment on a ship, and Read - disguised as "Mark Kidd" - joined the military and fought in the War of the Spanish Succession. Read married a Flemish soldier, but the soldier died young. When there was no more room for advancement in the British Army, Read decided to join the Royal Navy, and her ship was later taken by pirates. Read was forced to become a pirate, and she became known as "James Kidd", the "bastard son of William Kidd".
James Kidd became a well-known pirate in Nassau in the Bahamas, and he built a reputation for himself due to claiming that he was William Kidd's son. Kidd befriended pirate Edward Kenway, and he secretly joined the Hashshashin order after meeting assassin mentor Ah Tabai in Tulum, Mexico. In 1715, Kenway and Kidd raided one of Peter Beckford's plantations on Andreas Island, building a friendly camaraderie.In 1716, Kidd confirmed his suspicions about Kenway's abilities when Kenway solved a Mayan stelae puzzle, and Kidd revealed that he was a member of the Hashshashin. Kidd convinced Kenway to warn the Hashshashin of the Templar Order's plans to attack their bureaus across the Caribbean, and he convinced Kenway to assassinate several Templar agents due to the financial gain that Kenway could expect. Kidd and Kenway helped to defend Tulum from a British assault in 1716, and Kidd - working for the Assassins - and Kenway - motivated by self-gain - worked together to find "the Sage" Bartholomew Roberts and to fight against the Templars. The two occasionally argued due to Kenway's refusal to ignore the gold and join the Assassins, but they worked together several times; in April 1717, Read revealed her true gender to Kenway after taking off her disguise to distract the guards at the Templar Laurens Prins' Kingston estate.