As part of a five-year series commemorating the Civil War Centennial, this was the first stamp issued, marking the initial event of the war. The design features a large coastal artillery piece, a Columbiad cannon, of the type used during the bombardment of Fort Sumter. The choice of a green color for the stamp was a departure from the more common patriotic red and blue, perhaps to evoke a sense of the historical landscape. The issuance of this stamp was a significant moment of national reflection, acknowledging a painful and transformative period in American history. Fort Sumter itself, located on a man-made island in Charleston Harbor, was a symbol of federal authority in a seceded state, making it a flashpoint for the escalating tensions between the North and South.