The county was formed in 1920 from Charlton, Pierce, and Wayne counties and was named for Benjamin D. Brantley, a member of a prominent local family, although some historians claim the name honored State Senator William Goodman Brantley of Brunswick.
Since the Okefenokee Swamp is to the south and west of the county, passage through Brantley County was essential to the railroads running from the coast through the southern part of the state.
Fort McIntosh was built in the early years of the Revolutionary War to protect the extensive herds of cattle. It was placed under siege from Tories in 1777 and eventually surrendered.
Fort Mudge was built in the county at about the same time. This fort was immortalized by Walt Kelly in the "Pogo" comic strip.
Nahunta sounds as if it has an Indian name, but in fact the name is a colloquialism derived from railroad maps and a sign, "N.A. Hunter Siding."