Around 1782, the Tattnall family returned to Georgia. 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 commanded the Georgia militia in 1787 and led troops against the Creek 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. President George Washington nominated him for marshal of Georgia in 1794. He was promoted to brigadier general shortly before his election as governor in 1801.