Ocilla, the county seat of Irwin County, incorporated as a town on November 24, 1897. Ocilla is a version of an old Native American name, "Osceola."
During the Civil War, Irwinville, to the northeast of Ocilla, served as the county seat. In May 1865, after General Robert E. Lee had already surrendered at the Appomattox Courthouse, soldiers captured Confederate President Jefferson Davis in the town. In his hastiness to flee Union soldiers, Davis grabbed his wife's overcoat and threw it over his shoulders. For years thereafter, the public joked that Davis had tried to escape capture by disguising himself in women's clothing. Today, however, people reflect somewhat less mockingly on the Confederate president, and Irwinville visitors spend time remembering his history at the Jefferson Davis Memorial Historic Site.