“The Attack of the Ironclads” - The US Navy Attack on Fort Sumter and Charleston Harbor, April 7th, 1863

An Illustration in Harper's Weekly showing the Attack of the Ironclads

The Attack of the Ironclads: On April 7th, 1863 the industrial power of the United States was displayed as nine newly built ironclad ships advanced against Fort Sumter and the defenses of Charleston Harbor. The seven Passaic-class monitors each carried both an 11-Inch Dahlgren* and a massive 15-Inch gun, the heaviest yet sent to sea, which had been designed by Dahlgren - though cast hollow according to Rodman's methods. The turrets of the new monitors were protected with 11 inches of iron - 3 more than the prototype USS Monitor, a ship which was not present as she had been lost at sea while redeploying to the South Atlantic at the end of December 1862.

Rear Admiral Du Pont's flagship, USS New Ironsides, was armed with fourteen 11-Inch Dahlgrens and two 150-Pounder Parrott Rifles. New Ironsides, a conventional broadside ironclad with 4.5-inch thick forged armor plates was an extremely powerful vessel.

And then there was USS Keokuk - armed with a pair of 11-Inch Dahlgrens, each on a pivot mounting in a non-rotating tower casemate. With her armor, a novel layering of inch thick plates and layers of pine, she was certainly the least impressive of the Federal fleet, but she was to be placed last in line.

It was certainly the most powerful squadron that the US Navy had ever assembled, and it was arguably the most powerful squadron in the world - at least in a flat calm. The Navy Department ordered Du Pont to attack confident that his ships would be invulnerable to the smaller guns in the forts, and that the heavy ordnance of the ironclads would quickly reduce the masonry walls of Fort Sumter and lead to the capitulation of Charleston, the Seat of the Rebellion. Du Pont's plan was to have his squadron push into the harbor, take position on the western side of Fort Sumter, and concentrate the fire of his heavy guns upon a single section of the Fort's wall until it collapsed.

Events did not go to plan.

The advance was slow. USS Weehawken, the lead ship which had been equipped with a Ericsson-designed raft-like-structure with grappling hooks mounted on her bows in an effort to sweep torpedoes and obstructions in front of the ship, fouled her anchor in the contraption, and even once she got underway was slowed considerably by it. Still short of the obstructions but thinking his ship upon them, Captain John Rogers of Weehawken stopped his ship and threw the advance into confusion. Around 3:00pm the forts opened fire upon the ships, and the ships would begin to return fire around 3:15pm.

Some combination of the slow speed, very shallow water, and currents rendered New Ironsides difficult to control. She would fire only a single broadside at long range at Fort Moultrie. She did collide with two of the monitors, and the Confederates ashore thought at one point she was stopped nearly on top of a huge torpedo, but the engineer ashore could not get the electric charge to carry to the torpedo to detonate it. New Ironsides, the most powerful ship in the most powerful squadron in the world, contributed almost nothing to the action.

The monitors struggled. Though none of the guns ashore was sufficiently powerful to penetrate the their thick armor, the collective impact of dozens of hits did begin to disable some of the ships. USS Nahant retired after pushing as close as 600 yards from Fort Sumter with her turret disabled by the repeated blows and with casualties from boltheads flying inside the turret and pilot house after the structures were hit.

USS Keokuk, the last and weakest ship nevertheless continued forward as the line stalled and reached a position under 600 yards from the fort. Keokuk was taken under fire by Sumter and the batteries on Sullivans Island which resulted in the ugly duckling of the squadron being hit some ninety times in a half hour period - a number of the shots penetrating her unusual armor. She was holed below the waterline. Successfully withdrawn from the action, she would sink in the morning. Her guns would later be recovered, and one still guards Charleston Harbor, but that is another story.

Du Pont ordered his squadron to withdraw at 4:30pm. Around 5:00pm, the signal to cease fire was made. The battle, which had only really begun two hours before, had ended.

The experience ashore was different.

As the ironclads advanced upon Fort Sumter, the state flag of South Carolina was one of the flags flying above the fort. The palmetto of that flag recalls the June 28th, 1776 Battle of Fort Sullivan when another fleet, that of Royal Navy Commodore Peter Parker, thought that its material and technological superiority was great enough over Charleston's defenses to allow it to impose its will upon the city and its palmetto-log and sand fortress. Like the US Navy attempt, the Royal Navy had fought rather than bypass the defenses, and like the US Navy attempt, it ended in defeat.

Many of the US Navy reports comment on the accuracy and rapidity of the fire Forts Sumter and Moultrie, Batteries Wagner, Bee and Beauregard. Multiple captains claim that they were under the fire of 100 guns or more. They were not. Indeed, many accounts of this battle emphasize the huge disparity between the 32 cannons afloat and the hundreds ashore.

But the fleet was not engaging all of Charleston's defenses - only a segment of them. Two entire walls of Fort Sumter remained unengaged throughout the battle. At most, 76 Confederate cannons were engaged in the battle, but many only at very long range. And not even all the cannons that would bear were kept firing. The 32-Pounders in Fort Sumter's casemates seem to have been ordered to cease firing at points because the feeble contribution of their shot was not deemed to be worth the cost of the smoke of their discharges obscuring the aim of the heavy guns on the parapet above.

In the two hour battle, Confederate gunners fired around 2,200 rounds at the ironclads. Fort Sumter's four engaged 10-Inch Columbiads fired 120 rounds between them. The two 7-Inch Brookes accounted for 86 rounds. Battery Bee's five 10-Inch Columbiads accounted for 225 rounds - 45 rounds each on average. The US Navy ironclads reported receiving 439 hits. Thus, a bit better than one in five shots found its mark - all at more than 500 yards to well over 1,000 yards mainly against very small moving targets.

The gunners aboard the United States Navy squadron by contrast only fired 139 rounds, of which about 50 were shot and shell from the 15-Inch guns. Of all the cannons in the fleet, USS Montauk's 11-Inch fired the largest number of shots: seventeen. None of the 15-Inch guns was fired more than USS Weehawken's eleven times. The fire of the monitors was slow.

Nor was the fire of the monitors especially accurate. Around 34 of all types fired hit the broad and high walls of Fort Sumter - a hit rate only slightly better than that achieved by the forts' gunners against far, far smaller moving targets.

After the US Navy Squadron withdrew, both sides made plans to renew the action. Fort Sumter's garrison exchanged some of the lighter cannons one the east and northeast walls with heavier pieces which had remained unengaged during the day on the western side. Du Pont intended to repair and regroup and try again - until the reports of the damage sustained came in and he resolved that another attack would not fair better. The failure of the first attack and the decision not to renew would eventually cost him his command.

Fort Sumter's walls had withstood the massive impacts of 15-Inch shot and shell, and her gunners had stood at their posts as the walls of the fort quaked under the impacts. The damage was repairable, but sustained fire of this type could have caused catastrophic damage had it continued.

With the exception of the battered Keokuk, the ironclads of the US Navy were also repairable - most of them were fully fit for battle soon after its conclusion. But they had not proven invulnerable to the enemy's fire - even when the guns of the enemy were smaller and less powerful than their own.

The Confederacy had a major victory and the US Navy a biting defeat. Casualties were minuscule by the standards of Civil War battles, only a small handful of soldiers and sailors were killed and wounded in the battle.

The war - and the battle for Charleston - would continue.

See: Official Records of the Union and Confederate Navies in the War of the Rebellion ser.1:v.14. Pages 3-112.

Photo Left: Fort Sumter as seen from the grounds in front of Fort Moultrie. The shipping channel that the US Navy was seeking to Force is between the two forts.

Photo Right: A 10-Inch Confederate Columbiad which may have been present at the battle (it was cast in 1862) is shown at Fort Moultrie overlooking the shipping channel towards Fort Sumter. More photos of this cannon can be seen here: https://www.santee1821.net/preserved-artillery/10-inch-confederate-columbiads-at-fort-moultrie

Model of Fort Sumter in 1861 displayed at Fort Sumter. By 1863 the Fort's armament had been improved. Her barracks had only been partially rebuilt after the fires started in the 1861 battle, but she was substantially the same fort.

A Model of USS New Ironsides is displayed with a model of CSS David and a Confederate Torpedo at the South Carolina State Museum in Columbia, South Carolina

A Model of USS Weehawken is displayed at the South Carolina State Museum

A Model of USS Keokuk is displayed at Fort Sumter

Read about the recovery of the 11-Inch Dahlgrens of USS Keokuk here: https://www.santee1821.net/preserved-artillery/the-11-inch-dahlgren-of-uss-keokuk

The damage received by Fort Sumter on her engaged sides during the April 7th battle.