The USS Cairo is a City Class, Ironclad River Gunboat named for Cairo, Illinois. She was designed by Samuel Pook and was constructed in 1861 under a contract with James Eads & Co. in Mound City, Illinois, along with two other ironclads. Four others were constructed in a St. Louis, MO shipyard. Under the contract, James Eads agreed to deliver the seven ironclads in 100 days or pay a $200 per day fine. Eads delivered all the boats as promised with an average cost of $101,808. The USS Cairo was commissioned on January 16th, 1862.
The river ironclads were the backbone of the Union’s brown water navy and were designed to operate in both rivers and shallow coastal waters, most notably on the Mississippi River and its shallow tributaries. The ironclads were instrumental in suppressing Confederate shore batteries, destroying southern gunboats, and disrupting enemy supply ships. Along with her six sister ships, all City Class river gunboats were named for cities on the Mississippi and Ohio Rivers. Cairo’s sister ships were as follows: USS Pittsburgh, USS Saint Louis, USS Mound City, USS Cincinnati, USS Carondelet, and USS Louisville.
Gun Boat Characteristics
The City Class gunboats were 175 feet long and 52 feet wide. Each displaced 880 tons and although heavy only had a six foot draft. The flat, wooden hull’s draft was so shallow that it was joked that the gunboats could “navigate in a heavy dew.” The Cairo had a crew of 17 officers and 158 sailors, of which more than half were immigrants. The crew was made up of both black and white sailors and had crew members from France, Denmark, Germany, Russia, Ireland, England, and the Caribbean. Few of its crew members were actually sailors with past occupations being listed as teachers, farmers, and butchers. With little formal training, most of the crew learned their naval skills on the job. The Cairo’s captain was Lt. Commander Thomas O. Selfridge, who was known as an aggressive but skilled sailor and commander.
The Cairo was a steam powered boat. Its popular “Western Rivers” propulsion system was widely used at the time and is the only surviving example. Designed by A.T. Merritt, the steam powered boilers could generate 600 horsepower which was used to drive a 22-foot diameter, 15-foot-wide paddle wheelhouse. Under full steam the five boilers required at least one ton of coal per hour. The steam produced by the boilers drove two pistons, one on each side of the paddle, which moved oscillating arms that then rotated the paddlewheel to a top speed of six knots with the river current and approximately three knots against the current. The wheelhouse itself was unarmored and was vulnerable to plunging fire from enemy shore batteries situated on the bluffs high above the Mississippi River. The paddle wheel was constructed of iron, but its paddles were made from wood so they could be easily replaced by the gunboats carpenter. The Cairo was steered by two rudders located on either side of the paddlewheel via a cable connected to the pilot house.
Of note, Cairo also had several other interesting features. Due to the shallow draft of the boat, the uneven loads of the boilers, engines, and cannon tended to cause the bow and stern to sag. The gunboat utilized large “hog chains” to keep both ends of the boat from sagging under the weight on its decks. The gunboat also could utilize steam to power a capstan that could be used to pull in heavy lines and move cannon around the decks. In an emergency situation, the crew could insert large wooden spokes to manually power the system. Finally, the gunboat could divert water from the paddlewheel into the latrine to supply water to a shower head and a flush toilet.
Armament & Armor
The USS Cairo was armed with 13 heavy cannons, which required six men to man each. The gunboat’s armament included six 32 pounder Navy smoothbore cannon, three 42 pounder Army rifles, three 8-inch Navy smoothbore cannon, and one 30 pounder Parrott rifle. The ironclad gunboat had extensive armor for its time. It was protected by two-and-a-half-inch thick overlapping iron plates backed by oak planks between 12 and 25 inches thick. These thick wooden planks kept the iron plates from shattering when taking a hit. Armor was thickest around critical sections of the gunboat including the boiler and engine propulsion systems, located amidships, as well as pilot house and casemates.
Service History & Sinking
The Cairo was tasked, along with her sister ships, to patrol the Mississippi and Ohio Rivers and their tributaries in order to disrupt enemy forces and supply lines as part of the Union Army’s Western Gunboat Flotilla. She saw limited action after her commissioning, but did take part in the occupation of Clarksville, TN and Nashville, TN in February, 1862, the Battle of Fort Pillow and Plum Point Bend in May, 1862 and Memphis, TN in June, 1862. Other ironclads saw action in 1862 at Fort Henry and Fort Donelson as part of Gen. Grant’s operations in the western theater. Some also took part in the Red River Expedition to capture Shreveport, LA in 1864. After the naval engagement at Memphis, the Cairo returned to patrol duties on the Mississippi River until November 21st, 1862.
On December 12, 1862, Lt Cmdr Selfridge led a small flotilla of gunboats into the Yazoo River north of Vicksburg. He had been tasked with destroying Confederate gun batteries along the Yazoo’s shores as well as clearing the river of underwater mines (known during the Civil War as torpedoes). At a point approximately seven miles from Vicksburg, the Union naval force came under fire from the Confederates. Selfridge ordered his men to ready the guns and press on full steam ahead in order to suppress the enemy firing from the shore. As the Cairo passed other vessels into uncleared waters, two explosions tore through her wooden hull in rapid succession. The first ripped into the port bow causing extensive damage, while the second explosion struck the starboard side amidships. Selfridge ordered the Cairo to be beached and the call to abandon ship went out. The gunboat quickly sank in 36 feet of water with no loss of life and the crew was recovered by nearby Union vessels.
The exact cause of the explosions is debated, with historians split on what may have actually happened. The two schools of thought are that the Cairo may have been sunk by “torpedoes”, likely strung across the river, and possibly detonated electrically by Confederates on the shore utilizing a crude battery system. Others think that a similar torpedo setup may have been pulled along the hull of the Cairo by her forward movement which resulted in a point detonation once explosives came into contact with the gunboat's hull.
Recovery and Preservation
After being lost for nearly a hundred years, the Cairo was discovered again in 1956 and in 1960 several artifacts were recovered from the wreckage including the pilot house and a cannon. After years of being buried in the thick Yazoo River mud and silt, the Cairo was determined to be in relatively good condition. In 1964, the State of Mississippi assisted in the recovery, raising, and restoration of Cairo's remains and in 1972 Congress gave the ship to the National Park Service for display at the Vicksburg National Military Park. The gunboat is currently on display and visitors are able to walk through portions of the reconstructed remains. The adjacent museum also contains artifacts and personal items from crewmembers who had to quickly abandon ship. Many items remain in very good condition due to their preservation after being buried at the bottom of the Yazoo. The USS Saint Louis suffered the same fate as the Cairo, also being sunk by a mine in the Yazoo River in May, 1863. The USS Cairo is the sole survivor from the City Class River gunboats as the other six boats were sunk or sold for scrap after the war.
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