The U.S.S. Carondolet was one of the most famous Union ironclad riverboats during the American Civil War. She was one of seven similar ironclads, the ‘cities’ class, designed by Samuel Pooks. Like the C.S.S. Virginia, they were partly inspired by the floating ironclad gun batteries first used by the French during the Crimean War. They were based on flat bottomed Mississippi river boats, making them suitable for the shallow waters of that river.
Like those river boats, they were powered by a paddlewheel, in this case a centrally located wheel, protected within its own armoured compartment. Their guns were located in an armoured casement built onto the deck of the ship. That armour was 2.5 inches thick, much thinner than her ocean-going equivelents (U.S.S. Monitor had 4.5 inch armour, the C.S.S. Virginia 4 inch).The sides of that casement were sloped to help enemy shots bounce off the armour. The Carondolet was 175 feet long, displaced 512 tons but had a draught of only six feet. She was no slower than the early ocean going monitors, and was capable of reaching a speed of 7 knots (although her direction on the river had a major impact on this – the Mississippi current could be very powerful).
The contracts for the city class gun boats were offered for tender in August 1861. The Carondolet was built by James Eads in his St. Louis shipyard (it was Eads who had originally suggested the construction of this type of ship). She was launched on 12 October 1862 and sailed to the main Union base at Cairo, where she received her guns.
The river gun boats were equipped with gun ports in all four directions. They were equipt with a variety of weapons of vastly different quality. The Carondolet began her career with fourteen guns, three at the front, four on each side and two at the rear. The best guns available were 8 inch Dahlgren smoothbores, of which the Carondolet was given four (three firing forwards). The rest of her guns were a mix of ex-navy and ex-army rifled guns (one 50-pounder, one 42-pounder, six 32-pounders, one 30-pounder and one 12-pounder for the deck). This mix of armament was hardly ideal, and can only have complicated things for her crew, forcing them to maintain supplies of six different sizes of ammunition. During the war the 32-pounders were replaced by a combination of 9-inch smoothbores and 100-pounder rifles, increasing the number of types of guns on-board to seven!
The Carondolet was commissioned on 15 January 1862 and was almost immediately sent into action. The early campaigns in the west were dominated by the rivers, which had the potential to become highways for Union troops to penetrate deep into the south. The first successes were achieved on the Tennessee and Cumberland Rivers in northern Tennessee. The Confederate defensive line in the west included Fort Henry on the Tennessee River and Fort Donelson on the Cumberland River.
The expedition against these positions was led by General U.S. Grant, the Federal commander at Cairo. This was also the base of the river gunboat fleets, commanded since September 1861 by Flag-Officer Andrew Foote. Together they worked out a plan for a combined operation aimed at Fort Henry, the weaker of the two forts. The plan was for Foote’s ironclads to bombard the fort at the same time as Grant’s infantry attacked from the land. In the event, on 6 February the Carondolet went into her first action without the support of the army, who had taken longer than expected to reach their destination. She was commanded by Commander Henry Walke, later a rear-admiral and author of several articles on the achievements of the river fleet. During the bombardment of Fort Henry she fired 107 shots without suffering any casualties. The approach of Grant’s army had forced the virtual evacuation of Fort Henry. Only the artillerymen remained begin, to win enough time for the army to retreat to Fort Donelson. After an artillery duel lasting two hours, the fort surrendered to Foote’s river fleet.
Fort Donelson was not such an easy prospect. She was better sited that Fort Henry, making the fleet’s job much harder. Carondolet was the first ironclad on the scene, arriving on 12 February, the first day of the siege. The rest of Foote’s ironclads did not arrive until late on 13 February. When they finally got into action the next day, their main weakness was revealed. They were poorly protected against fire from above. Two of the four ironclads were partially disabled by shots from above, and had to be protected by the Carondolet and Pittsburgh. The Carondolet had been under fire for longer than the other three ships, and suffered heavier casualties – 5 dead and 28 wounded out of a crew of 251.
The river flotilla now turned its attention to the Mississippi River. This time the Confederate defences were more formidable, based on a series of forts stretching along the course of the river. Each one would need to be captured if the Union was going to gain control of the river. The first of these strong points, at Corinth, was abandoned before it could be attacked, but the next one, Island No. 10 on the Kentucky-Tennessee border provided a much bigger challenge.
A Union army under General John Pope had successfully captured New Madrid, downriver from Island No. 10, but on the Missouri shore. He was now stuck on the west bank of the river, while the Union gunboats were stuck above Island No. 10. Foote was convinced that it would be too dangerous for one of his ships to run past the guns. Walke did not agree. He was able to persuade Foote to let him make an attempt to run past the guns. At 10 p.m. on 4 April, he was proved right. The ship had been carefully prepared for her ordeal, with extra armour temporarily placed across her decks to protect her against plunging fire. Once past the guns of Island No. 10, the Carondelet along a second gun boat (the Pittsburg) that had also run past the guns helped Pope cross the Mississippi. On 7 April the remaining defenders of Island No. 10 surrendered to Pope.
The fleet’s next target was Fort Pillow. Here they suffered something of a defeat. The Confederates had also been busy building a river fleet, and on 10 May they attacked the Union mortar boats attacking Fort Pillow, catching them by surprise. However, the attack failed to achieve much, and the attacking ships soon had to retreat under the guns of Fort Pillow when the Union ironclads entered the battle.
Soon after that Fort Pillow was evacuated. The next target was Memphis, an important Confederate supply base and manufacturing centre. Many of their own river boats had been built at Memphis. The city fell to the Union fleet. On 6 June 1862 a combination of gun boats and rams captured or sank seven of the eight strong Confederate fleet guarding Memphis.
The capture of Memphis was the last of the easy conquests for the Carondelet and the river fleet. Their next target was Vicksburg, but that place was too strongly held for even a combined Union fleet, attacking from both ends of the Mississippi. This first attack on Vicksburg was called off when water levels in the river began to fall, threatening to cut off Farragut’s ocean going ships from New Orleans. However, before the attack was called off, the Carondelet was almost crippled in another surprise attack.
This time the attack was launched by the C.S.S. Arkansas, a Confederate ironclad that had been built on the Yazoo River. On 15 July the Carondelet, with the U.S.S. Tyler, was steaming up the Yazoo when she encountered the Arkansas. In the fight that followed both Union ships were badly damaged, while the Arkansas managed to fight its way through to safety under the guns of Vicksburg.
The Carondelet returned to Vicksburg the following year. Once again she was part of a fleet cooperating with General U.S. Grant and once again she was part of an attempt to run past Confederate guns, this time the guns of Vicksburg. Grant’s main problem was that he needed to get his army onto the east bank of the Mississippi, south of Vicksburg. In order to do this, he needed to get a fleet past the city. On 16 April the Carondelet was one of eight gunboats that ran past the guns of Vicksburg. Grant now had his fleet. On 29 April he used it to bombard the Confederate defences of Grand Gulf. Although those defences were largely silenced, Grant eventually decided to cross the river further south. After a skilful campaign (Big Black River), and a siege nearly two months long, Vicksburg surrendered on 4 July.
The fall of Vicksburg signalled the end of the Mississippi River campaign. The gunboat flotilla was split up and spread along the Mississippi, to guard its great length against any new Confederate attack. The Carondelet was to take part in one more major campaign before the war ended. March 1864 saw a combined army-navy operation on the Red River. The Red River ran through a prosperous part of Louisiana. A successful drive up the Red River would deny these resources to the Confederates, and even threaten Texas. Unfortunately, the army commander, Nathaniel Banks, failed badly. His retreat left the gunboat fleet badly exposed on the Red River. To make things worse, the water level was much lower than expected. There was a serious danger that the Carondelet would end her war in Confederate hands. The fleet only escaped when a series of dams were built to raise the water level in the river.
The Carondelet and her sister ships played a major role in the North’s victory in the Civil War. Without them the Confederate defences on the Tennessee, Cumberland and Mississippi Rivers would have been much harder to breach. Without them, Grant’s capture of Vicksburg would have been a much harder, much longer operation. The ironclad gun boats were one of the North’s war winning weapons.