In 1746 she gave birth to a daughter, Susannah, who died a year later. When her husband deserted her, she borrowed a male suit from her brother-in-law James Gray, assumed his name and began to search for Summs (she was to learn later that her husband had been executed for murder). According to her account, she joined General Guise's regiment in the army of Duke of Northumberland against Bonnie Prince Charlie, and deserted when her sergeant gave her 500 lashes. However, the chronology of her life makes it very unlikely that she ever served in Guise's regiment and this part of the story is likely to have been a fabrication.
Following the death of her daughter, she moved to Portsmouth and joined the Royal Marines. She boarded the ship Swallow at Portsmouth on October 23 1747 the ship sailed to Lisbon on November 1. Her unit was about to invade Mauritius but the attack was aborted. Her unit then sailed to India.
In August 1748 her unit was sent to an expedition to capture the French colony of Pondicherry in India. Later she fought also in the battle in Devicotta in June 1749. She was wounded eleven times to the legs and once to the groin. She either managed to treat her groin wound without revealing her sex or she may have used services of a sympathetic Indian nurse.
In 1750 her unit returned to England and traveled from Portsmouth to London, where she revealed her sex to her shipmates on June 2. She petitioned the Duke of Cumberland, the head of the army, for her pension. She also sold her story to London publisher Robert Walker who published her account, The Female Soldier, in two different editions. She also began to appear on stage in her uniform presenting military drills and singing songs. Three painters painted her portrait in her uniform and The Gentleman's Magazine reported her claims. She was honorably discharged and the Royal Hospital, Chelsea officially recognized Snell's military service in the November and granted her a pension in 1750 (increased in 1785) a rare thing in those days.
Hannah retired to Wapping and began to keep a pub named The Female Warrior (or The Widow in Masquerade, accounts disagree) but it did not last long. By the mid-1750s, she was living in Newbury in Berkshire. In 1759 she married Richard Eyles there, with whom she had two children. In 1772 she married Richard Habgood of Welford, also in Berkshire, and the two moved to the Midlands. In 1785 she was living with her son George Spence Eyles, a clerk, on Church Street, Stoke Newington.