He was born at Bonaventure Plantation, near Savannah, around 1764 to Mary Mullryne and Josiah Tattnall. When Americans loyal to the British king fled Georgia in 1776, Tattnall and his brother accompanied their father and grandfather, John Mullryne, to the Bahamas and then to England, where they lived for six years. The family estate, Bonaventure, consisting of almost 10,000 acres, was confiscated in their absence. (The estate became the Bonaventure Cemetery, a well-known site in Savannah.) While in England, young Josiah attended Eton College.
About 1782 Tattnall returned to America and joined the Continental army of General Anthony Wayne, then confronting British forces occupying Savannah. After the Revolutionary War (1775-83), Tattnall bought back a portion of Bonaventure and further pursued his interest in military affairs. He commanded militia light infantry in quelling a slave insurrection in 1787 and led troops against hostile Indians in 1788 and 1793. He was captain of the Chatham Artillery, the oldest militia unit in Georgia, and later colonel of an infantry regiment. He was promoted to brigadier general shortly before his election as governor.
Tattnall served in the state House of Representatives as a Jeffersonian Republican from 1795 to 1796. This was the period of the Yazoo land fraud, in which corrupt officials influenced the sale of millions of acres of state land. U.S. senator James Jackson resigned from the Senate and returned to Georgia to work for repeal of the legislation enabling the sale. Tattnall was one of Jackson’s party leaders in the legislature and played an important part in winning the votes needed to pass the Yazoo Rescinding Act of 1796. Afterward, legislators elected Tattnall to complete Jackson’s term of office, and he served three years in the U.S. Senate (1796-99).
After returning from Congress, Tattnall retired to Savannah for more than two years. In 1801 he was elected governor and served for one year. The only events of note during his administration were the first opening of the University of Georgia and the final disposition of Georgia’s northern and western boundaries. In addition, he signed a bill restoring to himself the balance of the family estate and clearing his father’s name.
Tattnall died at Nassau in the Bahamas, where he had gone for his health, on June 6, 1803; his body was returned to Georgia for interment at Bonaventure. His wife was Harriet Fenwick of Charleston, South Carolina, who had died the previous year. The couple had several children, of whom only three lived to adulthood. His son, the third Josiah Tattnall, was an American naval officer for more than fifty years and a noteworthy figure during the Civil War (1861-65).
Tattnall’s greatest contributions to Georgia were his service in the state militia and state legislature. His tenure as U.S. senator was unremarkable and his time in the governor’s chair too short to be of any consequence, yet he was held in high esteem by contemporaries. Tattnall County was created and named for him a month after his election as governor.