Dahlgren guns were muzzle loading naval artillery designed by Rear Admiral John A. Dahlgren USN (November 13, 1809 – July 12, 1870), mostly used in the period of the American Civil War. Dahlgren's design philosophy evolved from an accidental explosion in 1849 of a 32-pounder being tested for accuracy, killing a gunner. He believed safer, more powerful naval cannon could be designed using more scientific design criteria. Dahlgren guns were designed with a smooth curved shape, equalizing strain and concentrating more weight of metal in the gun breech where the greatest pressure of expanding propellant gases needed to be met to keep the gun from bursting. Because of their rounded contours, Dahlgren guns were nicknamed "soda bottles", a shape which became their most identifiable characteristic