USS Mound City was part of the City-class armored riverine gunboats. These boats were constructed during the American Civil War (1861-1865) to serve in the Western Gunboat Flotilla of the United States Army early in the conflict. As control of the Mississippi River, and all its attached waterways, was crucial to the North, it was desired that a fleet of river-capable warships be used to lay claim to such routes (and furthermore police them in future actions). The gunboats were also known as "Pook Turtles" after one of their creators - Samuel M. Pook.
The boats were specifically drawn up for operations on the winding Mississippi where the waterways ran both shallow and deep, narrow and wide. This would require a vessel with a shallow-enough draught as well as one with inherent agility. Add to this the required level of protection for the crew, machinery and ammunition stores and the requirement grew to become something of a challenge. The boats were fleshed out by engineer / inventor James Buchanan Eads with assistance from Union Commander John Rodgers and went on to involve Samuel M. Pook. Pook's appearance was of note for he held experience in the design and development of river-borne watercraft and was already serving the Navy Department in Cairo, Illinois.
With this base design in hand, the Army approved the construction of seven boats built to the Pook standard with a rather ambitious delivery date set for October of 1861 - it was not until the late January 1862 that the last boat was finally in the hands of the Army. The ships of the class were named USS Cairo, USS Carondelet, USS Cincinnati, USS Louisville, USS Mound City, USS Pittsburgh and USS St. Louis.
USS Mound City was constructed at the Mound City Marine Railway & Shipyard location and formally commissioned for service on January 16th, 1862.
The gunboat's design involved a thick armored casemate set over a wooden hull - as was the standard in ironclad design of the day. The hull line ran just above the waterline, which was acceptable for a river bound craft, and the forward, rear and side facings were distinctly angled for basic ballistics protection. The armor (of iron construction) reached 2.5" in thickness at the casemate and 1.25" at the pilothouse with more plating fitted to the forend of the boat than the aft as she was found to be "back-heavy" when she was finally delivered. The propulsion scheme was installed near midships and drove a wheel at the stern. A pair of smoke stacks protruded from the superstructure's roof line.
In her January 1862 guise, USS Mount City was equipped with 3 x 8" smoothbore guns, 4 x 42-pounder rifled guns, 6 x 32-pounder rifled guns and a single anti-infantry 12-pounder rifled gun. Smoothbore guns offered extended range at the expense of accuracy but their overall construction was not reliable. While more guns were originally intended for the boat, the ballooning weight brought on by the added armor plating nixed any more installations.
The armament scheme would change as the war drew on: In the middle of 1863, she was reworked with 3 x 8" smoothbores, 1 x 50-pounder rifled, 2 x 42-pounder rifled, 6 x 32-pounder rifled, 1 x 30-pounder rifled and 1 x 12-pounder rifled guns. In early 1864, her armament was addressed again, this time becoming 3 x 8" smoothbores, 4 x 9" smoothbores, 1 x 100-pounder rifled, 1 x 50-pounder rifled, 3 x 32-pounder rifled, 1 x 30-poumder rifled and 1 x 12-pounder rifled guns.
Displacement reached 520 tons (short) and she held a length of 175 feet with a beam measuring 51 feet and a draught of just 6 feet. The propulsion scheme involved a steam-driven wheel based in the stern of the hull and the boat could make headway at 9 knots. Aboard was a crew of 251 personnel.
USS Mound City was assigned to the Western Gunboat Flotilla as her first commitment and she took part in the Battle of Island No. 10 (February 28th - April 8th, 1862) and the Battle of Fort Pillow (May 10th, 1862). The Union claimed the victory in the former but lost the latter engagement (USS Mound City also took ram damage in the latter and barely escaped sinking). In the Battle of Saint Charles (June 17th, 1862), a Confederate shot pierced the hull and struck a steam drum, resulting in the deaths of 105 of the crew and wounding dozens. In October of 1862, she was transferred to the Department of the Navy and formed part of the Mississippi River Squadron where she would remain until the end of the conflict.
Under her new owners, the warship participated in Grant's Vicksburg Campaign that spanned from December 1862 until January of 1863 and resulted in a Union victory. Her guns were used in anger at Grand Gulf (Mississippi) and she ended her wartime career in the Red River Campaign (March 10th - May 22st, 1864) - the latter claimed by the Confederates.
With the end of the Civil War arriving in April of 1865, the Mississippi River Squadron was disbanded and USS Mound City was sold off for scrapping on November 9th, 1865.