Literally, before the war. General historical term referring to the period within the Imperium before the Civil War. specifically 210 to 604. The antebellum period was characterized by expansion of the Imperium, with large-scale colonization efforts, integration of numerous regions into Imperial society, and an overall mood of growth and exploration. With the end of the antebellum period, the Imperium turned more attention inward, devoting resources to internal development and consolidation.