Soon after they were married, George suggested to five sailors friends that they take up piracy. They had all been privateers and they accepted. George asked Rachel to join them, which she did. They used a friend's fishing schooner who took part of the loot as payment for the use of his ship. The crew used the boat for fishing, but once a storm hit, they put out a distress single luring ships to their doom. Once a ship stopped to help this 'fishing boat' they were attacked and killed. Then the loot would be transferred over to the Wall's boat and the aided ship would be sunk making it appear that the ship had sunk due to the storm. This scheme worked well for over a year until George Wall made a miscalculation regarding a storm (1782). Their schooner was caught in the storm and George and one other was swept overboard and their boat was in ruins. Rachel was rescued and taken back to Boston where she went back to her old job as a servant.

So used to robbery, Rachel continued her trade by stealing from seafarers while they slept upon their ships. She would board a ship and steal from the captain's head while the captain was sleeping. Arrested and convicted of robbery, she confessed to her crimes of piracy and stealing. However, she insisted that she never murdered anyone and that they crime she was currently in custody for, she was innocent. This did not sway the judge; Rachel was hanged on October 8th, 1789.