The Neosho-class monitors were a pair of ironclad river monitors laid down in mid-1862 for the United States Navy during the American Civil War. After completion in mid-1863, both ships spent time patrolling the Mississippi River against Confederate raids and ambushes as part of Rear Admiral David Porter's Mississippi Squadron. Both ships participated in the Red River Campaign in March–May 1864, although Osage supported the capture of Fort DeRussy in March and participated in the Battle of Blair's Landing in April. Osage was grounded on a sandbar for six months after the end of the campaign while Neosho resumed her patrols on the Mississippi. The latter ship supported the Union Army's operations on the Cumberland River and provided fire support during the Battle of Nashville in December. Osage, after being refloated and repaired, was transferred to the West Gulf Blockading Squadron in early 1865 for the campaign against Mobile, Alabama. During the Battle of Spanish Fort in March 1865 she struck a mine and rapidly sank. The ship was later salvaged and sold in 1867. Neosho was decommissioned after the war and remained in reserve until sold in 1873. Design and description The original plans for the Neosho-class ships, designed by James Eads, resembled the s with a draft of , but the successful performance of the during the Battle of Hampton Roads caused the navy to revise its requirement to include a gun turret. Eads responded with an impressive design that included a turret with of armor, a fully armored sternwheel and a draft of , but the navy wanted even less draft and rejected his design. Eads adopted a turtleback deck design that promised to only draw . The steam-powered turret was at the bow and they had a deckhouse between the funnel and the sternwheel, although another was later added between the turret and the funnel. The Neosho-class ships were long overall and had a beam of . When launched, they proved to have a draft deeper than planned and they measured 523 tons burthen. The ships had four steam boilers powering one two-cylinder, western steamboat-type engine that drove the sternwheel. The Neosho-class ships had a maximum speed of in service and they carried of coal. The ships' main armament consisted of two smoothbore Dahlgren guns mounted in a single turret that had an arc of fire of 300°. Firing the guns tended to jam the turret