USS Marmora was a sternwheel steamer that served in the Union Navy during the American Civil War. Marmora was built in 1862 at Monongahela, Pennsylvania, as a civilian vessel. Purchased for military service on September 17, she was converted into a tinclad warship. Commissioned on October 21, the vessel served on the Yazoo River beginning the next month. She encountered Confederate naval mines on the Yazoo on December 11, and was present the next day when the ironclad USS Cairo was sunk by two mines. After further service on the Yazoo during the Battle of Chickasaw Bayou in late December, Marmora was assigned in January 1863 to a fleet that was preparing to operate against Confederate Fort Hindman, but was not present when the fort surrendered on January 11 after the Battle of Fort Hindman. From February to April, Marmora participated in the Yazoo Pass expedition, and in June burned the settlements of Eunice and Gaines Landing, Arkansas after Union vessels were fired on by Confederate troops. In August, Marmora participated in some activities on the White and Little Red Rivers while the Little Rock campaign was beginning, and patrolled on the Mississippi River late that year. In February 1864, she participated in another movement up the Yazoo River, and fought in the Battle of Yazoo City on March 5. Continuing to serve on the Mississippi River, Marmora was declared surplus in May 1865 and was put in reserve status at Mound City, Illinois the next month. On July 7, she was decommissioned, and was sold at public auction on August 17. Nothing further is known about Marmora after her sale. Construction and characteristics Marmora was built in 1862 at Monongahela, Pennsylvania, at the shipyard of William Latta. She was built for ship captain James McDonald, who had previously operated another ship with the same name. She was also known as the Marmora No. 2, and the name originated with the island of Marmara. Marmora had a tonnage of 207 tons, was long, had a draft of when "deeply loaded", and had a beam of . A sternwheel steamer, her paddle wheel was in diameter, with paddles that were long. Propulsion was provided by two steam engines, which had cylinder diameters of and a stroke of . Steam was provided by two Watson and Monroe boilers. Each boiler had three and three flues. Marmora had a top speed of ,