Born near Savannah, Georgia, at Bonaventure Plantation in the early 1760s (he was the first native-born Georgian governor after the state was admitted into the Union) to Mary Mullryne and Josiah Tattnall, he studied at Eton School before joining Anthony Wayne's troops at Ebenezer during the American Revolutionary War.

[2][3] Mullryne, who also built the third Tybee Lighthouse in 1773, established a small family graveyard on the grounds, which eventually formed the nucleus of the present-day Bonaventure Cemetery.

After living in the Bahamas for six years, the family later moved to England, where Tattnall attended Eton School.

Josiah Tattnall joined the Continental Army under General Anthony Wayne, helping remove Savannah from British rule.

After the war, Tattnall bought back a portion of Bonaventure from John Habersham and continued his interest in the military.

He was captain of the Chatham Artillery, the oldest militia unit in Georgia, and later colonel of an infantry regiment.

Jackson resigned his position as U.S. senator to return to the Georgia General Assembly, where he and Tattnall led the campaign against the sale of the Yazoo lands.

After the Rescinding Act of 1796 was passed, Tattnall was elected by the General Assembly to take Jackson's Senate seat, where he served from 1796 to 1799.