Harry Turtledove here breaks with the series' previous practice of having Atlantean events closely mirror American ones. While the events of "Nouveau Redon" in Opening Atlantis parallel the French and Indian War, and those of United parallel the American Revolution, the war in this volume is not an obvious analog of the American Civil War. Rather, the Insurrection is similar to John Brown's original intent for a general uprising across the Southern US; i.e. the slaves freeing themselves without waiting for the Federal government to grant emancipation, resulting in the Southern aristocracy begging the Northern government for protection rather than seceding into a Confederacy.
Terry Bisson's Fire on the Mountain (1988), which has an 1859 break-point, follows a 1959 slice-of-life in the Afrocentric nation which seceded from the U.S. under John Brown's leadership, and reached a technologically advanced utopia far ahead of OTL.