(StwSt: t. 207; l. 155'; b. 33'5"; dr. 4'6"; s. 6.9 k. a. 8 24‑pdrs., 2 12‑pdrs., 6 14‑pdr.)
Marmora, sometimes spelled Marmara, is an island in the sea of Mormora where quarries of white marble with black streaks are found.
Marmora, a stern wheel steamer built at Monongahela, Pa., in 1862, was purchased by the Navy at St. Louis, Mo., 17 September 1862 from Messrs. Brenan, Nelson, and McDonnell; and commissioned at Carondelet, Mo., 21 October 1862, Capt. Robert Getty in command.
Early the next morning she stood downriver to join the Mississippi Squadron in operations against the Confederate river stronghold at Vicksburg. Marmora's first action occurred when she attacked and destroyed several barges at Lake Providence, captured two skiffs and demolished a flatboat further down stream. On 29 November Marmora discovered heavy enemy fortifications 20 miles from the mouth of the Yazoo River; taking special care to avoid any encounter with them until in company with the fleet.
On 5 December, Marmora helped to refloat ram Queen of the West, aground on Paw Paw Island. On 11 December she ran 20 miles up the Yazoo River and discovered several suspicious looking objects floating on the river. When she fired into one of them, a tremendous explosion occurred which shook the ship from stem to stern, though at a distance of 50 feet or more. She carefully avoided the others and left final destruction of the remaining mines to riflemen ashore.
The next day, Marmora led Signal, Cairo, and Pittsburg up the Yazoo until the Union ships sighted several torpedoes. Cairo commenced shelling the right bank and sent out a boat to investigate the nearest torpedo. As the boat towed the torpedo alongside, another infernal machine exploded under Cairo, ripping the bottom entirely out. As she rapidly sank, Marmora and the other Union ships sent boats to the rescue and saved everyone.
Marmora and her sister ships continued to remove torpedoes and to cooperate with the Army during probing actions seeking to find a weakness in Vicksburg's defenses. On 27 December the squadron heatedly engaged Confederate batteries at Drumgould's Bluff. That day, Porter reported the Yazoo clear of torpedoes within one‑half mile of the southern guns.
The next day, his gunboats' mobile fire kept Confederate troops off balance while General Sherman's troops landed to attempt to capture strong southern works at Chickasaw Bluff, a vantage point upstream from Vicksburg. Two days later, despite excellent support from naval guns. Sherman's troops, hindered by heavy rains and opposed by strongly reinforced Confederate units, reluctantly withdrew.
Marmora participated in the attack on Fort Hindman, Ark., 4 to 11 January, when it was taken; the post was 80 miles above the mouth of the Arkansas River and was consequently important in Union efforts to control the flow of supplies from the west across the Mississippi at Vicksburg and to southern armies in the east. In February, Marmora joined four other ships in preparations for the Yazoo River Expedition, departing Helena 27 March. The joint Army‑Navy Expedition captured CSS Fairplay and destroyed newly constructed Confederate batteries 20 miles up the Yazoo. For the next few months, Marmora concentrated on patrol duty and supply runs. Guerrilla activities caused Marmora to stop at Gaines' Landing 13 through 15 June to burn houses. Steaming up the White and Little Red Rivers 8 August, the ships sought information on the location of General Price's army, the ships found St. Charles, Ark., deserted as Union forces had taken it 16 June and had control of White River. Cavalry from the ships did encounter Confederate resistance on landing at Devall's Bluff 17 August. In November Marmora worked at the mouth of the Yazoo to prevent Confederate blockade of the river.
Although Union forces had taken Yazoo City, their position was not secure. Confederates attacked the city en masse 8 March 1864, causing Marmora and other rams to steam to the rescue. Marmora remained off this point with the other ships for several months, as Union forces mounted the campaign in Red River. Marmora next returned to Mound City and was placed in reserve while still in commission. After fighting stopped, she decommissioned 7 July 1865 and was sold at Mound City to D. D. Barr 17 August 1865.