Although horizontal fire naval guns propelling explosive shells had entered all major navies by the 1840s (see Paixhans gun), there was still room for a specialized vessel on occasion. During the American Civil War, the Union fleet included armored gunboats armed with 13 inch mortars; the weapon weighed 17,250 lbs and its bedding another 4,500 lbs. They fired 204-lb shells, with a bursting charge of 7 lbs of gunpowder, and had a range of three miles. At this distance, the projectile spent 30 seconds in flight. They were used to attack several forts, for example Fort Pulaski, Georgia.