Because of the speed at which the American Civil War evolved, both sides enacted furious procurement programs in an effort to stem the advancements of the other. This often meant attaches traveling overseas to secure small arms, artillery, and ships. In the case of the latter, it also proved common practice to simply modify an existing vessel for war - as was the case with USS Benton of the Federal Navy.
The vessel carried the name of former U.S. Senator Thomas Hart Benton (1821-1851).
USS Benton was formed around the structure of an existing catamaran "snagboat", a river-born barge with good shallow water properties. The hull was purchased in November of 1861 for $2,600. Her completed profile was consistent with ironclads of the age, exhibiting sloped sides with cannon ports dotting her length. Her roof was primarily flat and serviceable as a walking platform. A pair of smoke funnels - seated side-by-side at midships - broke up her silhouette as did the pilot house at front and the housing for her stern paddlewheel. Assault boats were carried over her sides. Due to her original catamaran arrangement, a new bow was designed, built, and added to the existing structure to complete her look. Her complete crew complement numbered 176 officers and enlisted personnel. Dimensions included a length of 202 feet, a beam of 72 feet, and a draught down to 9 feet.
Benton 's casemate was wholly covered in iron for maximum protection - a quality not common for early-war ironclads. Protection reached up to 2.5 inches while this armor was backed by up to 34 inch thick wood.
Armament for Benton evolved over the course of her service tenure. Beginning in February 1962, she carried a battery of 2 x 9" (228mm) Dahlgren smoothbore guns, 7 x 42-pounder James rifled guns, and 7 x 32-pounder Dahlgren rifled guns. In August of 1962 she was to take on a battery of 2 x 9" Dahlgren smoothbores, 2 x 50-pounder Dahlgren rifles, 4 x 42-pounder James rifles, 8 x 32-pounder Dahlgren rifles, and a sole 12-pounder Dahlgren howitzer. Come January of 1863, she was fitted with 4 x 9" Dahlgren smoothbore guns, 2 x 50-pounder Dahlgren rifled guns, 4 x 42-pounder James rifles, 6 x 32-pounder Dahlgren rifles, and 1 x 12-pounder Dahlgren howitzer. In December of 1863, her finalized battery consisted of 8 x 9" Dahlgren smoothbores, 2 x 100-pounder Parrott rifles, 2 x 50-pounder Dahlgren rifles, 4 x 32-pounder Dahlgren rifles, and 1 x 12-pounder Dahlgren howitzer. In this form, her sixteen gun battery made Benton one of the most powerful river gunships available to either side of the war.
Benton's propulsion system ultimately became her greatest failing. The vessel relied on a stern-mounted, steam-driven paddlewheel powered by two inclined engines. The configuration made the boat hardly agile and her turning radius was excessively wide, becoming and a time-consuming process to bring her bow about. Maximum speed in ideal conditions was 5.5 knots.
The vessel underwent her conversion at St. Louis, Missouri for service with the Western Gunboat Flotilla - interestingly of the United States Army and not Navy (the first three commanders of the Flotilla were in fact Navy men but fell under the direction of the Army). Benton was commissioned on February 24th, 1862 and was immediately put into action along the critical Mississippi River waterway and its many arteries. During this period, Benton took part in securing the surrenders of Island No. 10, Fort Pillow, and the city of Memphis, TN from the Confederates. She then faced off against CSS Arkansas near Vicksburg, MS and survived a ramming attempt before steaming up the Yazoo River a time later. During October of 1862, she was handed over to the U.S. Navy where she served as flagship (until 1863) of the Mississippi River Squadron with David Porter in command.
In operation along the Yazoo River once more during December of 1862, Benton took fire from Confederate guns and suffered damage but the vessel remained in service. In April of 1863, she managed to join several other Federal ships in bypassing the Confederate defenses at Vicksburg. She was then used to bombard the enemy stronghold at Grand Gulf, MS. In May, Benton used her guns in anger against Confederate positions at Fort DeRussy, AR and added firepower during the siege of Vicksburg - the strategically important river city fell on July 4th.
From March to May of 1864, USS Benton served in the Red River Campaign on Louisiana waters, marking her last notable actions in the American Civil War. With the war officially marked as over on May 9th, 1865, Benton returned to Louisiana waters in June to complete her service.
On July 20th, 1865 Benton was formally decommissioned which led to her sale on November 29th - ending her days as a naval fighting warship.