Sassacus-class gunboat

The Sassacus-class gunboat was a series of 28 wooden side-wheel gunboats built for the Union Navy during the American Civil War. As double-ended gunboats, the vessels were intended for operations in shallow water throughout the Confederate States and were used to maintain the Union Blockade. They were the most produced class of warships built in the United States at the time. Almost every ship participated in the war, although they were obsolete during peacetime. By 1870, eight years after construction began, almost every ship had been sold off for civilian use.

During the American Civil War, the Union Navy ordered the mass construction of double-ended gunboats. The gunboats, with a shallow draft and identical fore and aft, were intended for littoral and riverine operations against the Confederate States. Compared to other gunboats, the double-ended vessels could shoot in either direction without the need to turn around. The ships were primarily propelled by two side-wheels mounted amidship, although they were also equipped with two masts. The first twelve double-ended gunboats formed the heterogeneous Octorara class,^[1]: 109 and the Navy considered the design of Port Royal best of the class. Criticism of earlier Unadilla-class gunboats were that the ships were small and slow, so the Navy enlarged the double-ended gunboat design to produce the Sassacus class.^[2]: 288

The Sassacus-class design featured a length along the waterline of 240 feet (73 m), beam of 35 feet (11 m), mean draft of 8 feet 6 inches (2.59 m), and a displacement of 1,173 tons.^[1]: 114 The ships could carry 201 tons of coal, which was fed to two boilers that powered an inclined direct-acting engine to turn two side-wheels that produced 872 indicated horsepower (650 kW) and 12.1 knots (22.4 km/h; 13.9 mph) across each ship.^{[1]: 38 [3]: 131}The hulls were framed with white oak and planked with white pine, with metal bulkheads on each side of the engine rooms and a wooden bulkhead in the fore and aft. The ships were rigged as schooners and had a compliment of 149 enlisted sailors and 14 officers. While varied, initial armament consisted of two 100-pound (45 kg) pivot guns on the fore and aft along with four 9-inch (23 cm) Dahlgren guns and two 24-pound (11 kg) howitzers.^{[1]: 114–115}

The design was modified in several gunboats. Wateree was built with an iron hull, Eutaw included experimental superheating boilers, and Algonquin was fitted with machinery designed by E. N. Dickerson to investigate his design, which was a failure.^{[1]: 115–117} The Sassacus-class design was later enlarged to produce the seven iron-hulled Mohongo-class gunboats, the third and final series of American double-ended gunboats built during the war.^[1]

Construction contracts were awarded during the Autumn of 1862,^[3]: 131 with eighteen awarded to civilian shipyards and ten to government-operated navy yards. All but three ships were completed in time to join the war effort, and Algonquin was the only gunboat not to be commissioned.^[1]: 113 Several ships suffered from poor construction; problems included Tallapoosa's deck that threatened to collapse under the weight of the guns and Ascutney having been condemned due to structural faults less than two months after entering service.^[1]: 116 Further issues arose when the Navy was unable to find contractors willing to build the ships' engines on short notice. The shortage was resolved by Engineer-in-Chief Benjamin Isherwood, who traveled across the North and negotiated agreements to build the steam equipment.^[4]: 11-12 The 28 ships was the most numerous class of warship ever built in the United States at the time, and held the record until World War I.^[2]: 288

Once commissioned, the gunboats were assigned to squadrons that maintained the Union Blockade. They captured various Confederate vessels and took part in Union expeditions up Southern rivers or assaults on Confederate forts.^{[5]: 38–39} The only war-time loss was Otsego, which sank after she struck two mines in the Roanoke River.^[1]: 113 When the Civil War ended, the Navy no longer had a need for double-ended gunboats;^[1]: 120 by 1869, all of the vessels that remained were decommissioned and sold off for civilian use. The exception was Tallapoosa, which was retained as a training ship for the US Naval Academy and rebuilt in 1872.^{[5]: 39–40}