Her date of birth is in dispute among historians because of a reference to the "Peace of Ryswick" by her contemporary biographer Captain Charles Johnson in A General History of the Pyrates. He most likely made an error, intending to refer to the "Treaty of Utrecht." The discrepency would place her birth either c.1670 or c.1690. It is more likely that she was born the latter, which would mean she was the very typical age of 28 at the time of her piracy.
Mary's mother began to disguise illegitimately born Mary as a boy after the death of Mary's older, legitimately born brother, Mark. This was done in order to continue to receive financial support from his paternal grandmother. The grandmother was apparently fooled, and Read and her mother lived on the inheritance into her teenage years. Still dressed as a boy, Read then found work as a footboy, then soon found employment aboard a ship.
After learning the harsh realities of the sea life, she jumped ship and joined the British military, allied with Dutch and Austrian forces (again - this could have been during the Nine Years War or more likely during the War of the Spanish Succession). Read, in male guise, proved herself through battle, but she fell in love with a Flemish soldier. She dressed as a woman for the only time in her life to marry the soldier. They used their military commission & gifts from intrigued brethren in arms as a funding source to open an inn named "The Three Horseshoes" near Breda Castle in The Netherlands.
Upon her husband's early death, Read resumed male dress and military service in Holland. With peace, there was no room for advancement, so she quit and boarded a ship bound for the West Indies.
Still dressed as a man, Read was soon recruited to Rackham's crew where she became familiar with Bonny. She and Bonny became close companions. Rackham allowed her to stay on as a member of his crew even after finding out that she was, indeed, female. Eventually, Read and Bonny would wear mens clothes while attacking another ship, and women's clothes at other times.
During the subsequent duel the older man stumbled during a thrust. Legend has it that Read ripped her shirt open, revealing her gender. Supposedly, in the moment of the pirate's surprise & hesitation, she quickly grabbed his cutlass and killed him. It is agreed among historians that she prevailed in the death match, and her lover showed up on time for his duel.
Rackham and his crew were sentenced to hang for acts of piracy, as were Read and Bonny. However, the females escaped the noose when they revealed they were both "quick with child" ("Pleading the belly"), so they received a temporary stay of execution. Read was believed to have been pregnant by the artist, whom she considered her legal husband before God. Bonny was believed to have been pregnant by Rackham.
Read died in prison in April 1721, by fever possibly during childbirth, but there is no record of burial of her baby. Bonny disappeared from the historical record, presumed to have lived a long life in Colonial America.