During the Civil War, the South used an 18th-century concept called the floating battery–naval guns mounted on some sort of craft that had to be towed into position. Unable to maneuver to avoid gunfire, batteries usually were covered with iron plate.
The principal difference between a floating battery and an ironclad warship was propulsion. During discussions with the naval board on ironclads, Union inventor John Ericsson wrote, ‘This plan of a floating battery is novel, but seems to be based upon a plan which will render the battery shot and shell proof.’
Writing after the war, Ericsson traced the idea of a floating battery back to designs submitted to the Directory, France’s executive body, during the French Revolution. Early in the 19th century, American inventors proposed several designs of their own. Floating batteries reached the height of their popularity during the Crimean War. The chief proponent was France’s Napoleon III, who built several, including three batteries that were used on October 17, 1855, in the allied attack on Kinburn.
Efforts by the United States to build a floating battery actually antedated the French models. In 1842, Congress authorized construction of the Stevens Battery for harbor defense. When experiments showed the iron plate could not withstand a cannon shot, the government rejected the proposed battery. In 1861, the Navy rejected it again. The next year the ironclad board sent Captain Charles Henry Davis to inspect the battery, but he rejected it a third time.
The South began work on its first floating battery before the war. In early 1861, Lieutenant John Hamilton, the son of a former South Carolina governor, began building a floating battery in a dry dock in Charleston that he hoped to tow near Fort Sumter to batter down the gorge wall. One hundred feet long and 25 feet wide, the battery had two layers of railroad iron protecting the guns. Hamilton used sandbags to counterbalance the weight of the four large naval guns. Some men refused to serve on the unwieldy battery, nicknaming it the ‘Slaughter Pen.’ General P.G.T. Beauregard sent it to the western end of Sullivan’s Island.
Subsequently, the floating battery participated in the bombardment of Fort Sumter, receiving several hits in return. The Confederates later broke up the battery to use the iron plate in construction of an ironclad.
Southerners employed several floating batteries out of necessity. In 1862, private resources were used to build the ironclad Georgia to protect Savannah. Although designed as a ram, her engines were so weak that she had to be towed into firing position. She was later destroyed to keep Maj. Gen. William Sherman’s men from capturing her in 1864.
Another Confederate ironclad used as a floating battery was Louisiana. Like Georgia, Louisiana was designed as a ram, but Flag Officer David Farragut’s assault on New Orleans came before her engines were ready. On April 21, 1862, Brig. Gen. Johnson K. Duncan, commanding the forts downriver from New Orleans, wrote about the decision to use Louisiana as a floating battery: ‘It was not within the range of possibilities that she could be regarded as an aggressive steamer or that she could be brought into the pending action in that character. As an iron-clad invulnerable floating battery, with sixteen guns of the heaviest caliber, however, she was then as complete as she would ever be.’
Commander John K. Mitchell took Louisiana downriver near Fort St. Philip, where he could bring her bow guns to bear on the Union fleet if Farragut attempted to storm past the fort. While they waited for the Union attack, 50 mechanics worked to try to get her machinery functional, but Farragut struck first. As his ships steamed past the fort, Louisiana poured shot into them. Mitchell reported, ‘The enemy returned the fire of the Louisiana in passing with grape, canister, and shell, but without serious damage to her hull.’
The subsequent fall of New Orleans doomed the Confederate forward positions. The crew scuttled Louisiana to keep her from falling into Union hands.
The Confederates employed another floating battery, New Orleans, on the upper Mississippi. Originally designed as a dry dock rather than a ship at Algiers (across the river from New Orleans), the floating battery had a unique defensive system. A pumping engine in the hold allowed the crew to lower it until the deck was flush with the water. (While this protected New Orleans from the relatively flat trajectories of naval guns, it was unprotected from the plunging shots of mortars.)
Late in 1861, the Confederates towed New Orleans upriver. Near Columbia, Ark., the steamer Red Rover, under the command of Lt. Cmdr. John J. Guthrie, took it in tow, hauling it as far north as Columbus, Ky., where it arrived on December 11. On January 7, 1862, it had its first encounter with the enemy as Union Navy ships approached. Guthrie lowered the deck to the river’s edge and cleared for action. Neither side fired, and at 1 p.m. the Union ships withdrew.
With the fall of Forts Henry and Donelson to the east, the Confederate position at Columbus became untenable. Guthrie towed New Orleans downriver to Island No. 10, where it was anchored near the western end of the island. On board New Orleans were the Pelican Guards, one company from the 1st Alabama and one company from the 46th Tennessee. When Brig. Gen. John McCown ordered away this last unit, Guthrie had to stop using two guns.
On January 18, Beauregard ordered Guthrie to Memphis to supervise the ongoing construction of ironclads there. Lieutenant Samuel W. Averett took command of New Orleans. While the Union Navy bombarded the Confederate defenses around Island No. 10, New Orleans lay moored in the river, essentially a spectator to the conflict, since its guns lacked the range to reach the Union boats. New Orleans did fire a shot at a transport to test the range of its guns; the shot missed, but the boat withdrew upriver.
By the time the Union Navy arrived at Island No. 10 in mid-March, Confederate defenses were already crumbling. Major General John Pope marched his Federal Army of the Mississippi through a flooded swamp to capture New Madrid, Mo. With its fall, he effectively controlled the western bank of the Mississippi. Batteries placed at strategic points along the river hampered Confederate movements. Pope now controlled the Confederate left flank, and threatened the remainder of their defenses. Only the fact that the two armies were on opposite sides of the river delayed the collapse of the Southern defenses.To cross the river, Pope’s engineers laboriously cut a canal through a swamp that allowed shallow-draught transports to pass, but ironclad gunboats drew too much water to get through. With Confederate batteries mounted at landing sites on the other side of the river, the transports were useless to Pope unless he found a way to silence the Confederate guns.
No doubt inspired by the presence of New Orleans, Pope later began work on his own floating battery. ‘There seemed little hope of any assistance from the gunboats,’ he wrote. ‘I therefore had several heavy coal-barges brought into the upper end of the canal, which during the progress of the work were made into floating batteries. Each battery consisted of three heavy barges, lashed together and bolted with iron. The middle barge was bulkheaded all around, so as to give 4 feet of thickness of solid timber both at the sides and on the ends. The heavy guns, three in number, were mounted on it, and protected by traverses of sand bags. It also carried 80 sharpshooters. The barges outside of it had a first layer in the bottom of empty water-tight barrels, securely lashed, then layers of dry cottonwood rails and cotton bales packed close. They were floored over at top to keep everything in its place, so that a shot penetrating the outer barges must pass through 20 feet of rails and cotton before reaching the middle one, which carried the men and guns.’
Pope intended to tow the floating battery into the river and let it drift down to the crossing point, where it would anchor and open fire on the Confederate defenses. Ultimately, he did not have to use the floating battery because two ironclads ran past the Confederate defenses to join him.
Once Flag Officer Andrew Foote gave his approval to test the Confederate defenses, the Navy began softening up the Confederate batteries to ensure the safety of Captain Henry Walke and his ironclad Carondelet. The most famous of these actions was the raid on the first Confederate battery on the Tennessee shore, but the presence of New Orleans still worried the Federals–Carondelet would come very close to the battery. The Navy concentrated its fire on New Orleans early in April.
Despite inaccurate fire from long range, some guns and mortars found their target. Gunfire sank the flatboat that the Pelican Guards used as quarters, and a rifle shot wrecked one gun. Mortar shells and rifle shots so perforated the side of New Orleans that it careened to port. Water washed over the deck and almost reached the muzzles of the guns.
Averett had to get the battery out of range to repair it. New Orleans hastily dropped downriver, where the crew pumped out the water, finding two 3-foot holes caused by mortar shells below the waterline. They repaired all the damage within 24 hours. Brigadier General W. W. Mackall, the new Confederate commander, ordered New Orleans moored off the southern end of Island No. 10.
During the night of April 4, Carondelet slipped past most of the Confederate batteries unnoticed. The last obstacle was New Orleans. Given more warning than the other batteries, it managed to fire two shots at Carondelet. One embedded itself in the coal barge on the port side of the Union vessel, coming close to hitting the ironclad.
Under the protective guns of Carondelet, Pope’s army successfully crossed the Mississippi, causing the Confederate defenses to collapse without much of a struggle. To keep the Union from capturing New Orleans, Averett scuttled it and surrendered to a Union cavalry unit.
Except for some minor use of Georgia later in the war, the Confederate use of floating batteries ended with the sinking of New Orleans. A stationary target covered with iron plate simply was no match for the firepower of the Union Navy.
This article was written by Robert Collins Suhr and originally appeared in the July 1996 issue of America’s Civil War magazine. For more great articles be sure to subscribe to America’s Civil War magazine today!