USS Keokuk was developed as an all-iron casemate ironclad, one of the first of its kind (wood sparingly used in her construction), for the Union Navy during the American Civil War (1861-1865). She was ordered in March of 1862 as the War Between the States raged on. She was constructed by the shipbuilder Charles W. Whitney of New York and launched on December 6th, 1862, officially commissioned in March of 1863. She was named in honor of the city of Keokuk, Iowa (she was originally to be called "Moodna" when under construction).
As completed, Keokuk displaced 688 tons (short) and held a length of 159.5 feet, a beam of 36 feet and a draught of 8.5 feet. Internally she was crewed by ninety-two personnel and carried 2 x Two-cylinder steam engines of 250 horsepower each driving a pair of screws under the waterline. Maximum capable speed was nine knots. Armament was just 2 x 11" (280mm) Dalhgren smoothbore guns, each unit held in individual casemates fore and aft of midships with these casemates given three gun ports apiece. Armor protection reached nearly six inches at some parts of the boat. In profile, the vessel held a well-tapered hull design with a prominent rammer at the bow and propellers at the stern. At midships was a single smoke funnel and this was bookended by the casemate pair.
Keokuk's first (and last) call-to-action was as part of the Union blockading / attack force at Charleston, South Carolina. The battle occurred on April 7th, 1863 and came to be known as the First Battle of Charleston. The Confederates held advantageous positions at Fort Sumter and Fort Moultrie and gun batteries coupled with incoming flood tides made management of the warships difficult for crews. USS Keokuk managed to reach within 600 yards of Fort Sumter which ultimately led to her unceremonious end.
The warship was hit by some ninety cannonballs launched from Confederate positions at Fort Sumter and Sullivan's Island. Despite her iron construction, the warship could do little against such a barrage and withdrew under power. During the next morning, the ironclad had taken on too much water and ultimately sank off of the coast of Morris Island (April 8th, 1863). Now abandoned, the warship was later visited by Confederate forces who claimed her guns and remounted them elsewhere - including at positions within Fort Sumter itself.
USS Keokuk led one of the shortest service lives of any vessel in the American Civil War, operating from March of 1863 until the April of that same year. Such ended the career of this experimental casemate ironclad.