USS Monitor Gun Carriages

March 8–9, 2021, marks the 159th anniversary of the Battle of Hampton Roads, also known as the Battle of the Monitor and Merrimack. This battle is significant as the first fight between two ironclad warships, USS Monitor and CSS Virginia. Today’s post comes from Rachel Bartgis, conservator technician at the National Archives at College Park, MD.

Battle between the Monitor and Merrimac, Hampton Roads, Virginia, March 9, 1862. Copy of engraving by Evans after J.O. Davidson. (National Archives Identifier 530500)

NARA’s Cartographic Branch recently completed more than 8,880 item descriptions for one of its highly referenced naval series, Construction and Design Drawings of Guns, Related Machinery and Parts, 1862-1921, which includes plans for the gun carriages housed within USS Monitor’s turret. 

The USS Monitor’s revolving turret was a mechanical marvel, the first in the world to be mounted on a ship. It fired nearly 360 degrees around the ship, with its sole blind spot being where the ship’s pilot house sat on the deck. The turret housed two 11-inch Dahlgren guns resting on specially designed gun carriages, and it was the carriages that made the Monitor’s revolving turret possible. 

XI In. Gun Carriage in Turret of Monitor. (National Archives Identifier 149281932)

The carriage sides were made of two iron brackets with wooden cores, and the fore and aft ends consisted of an iron plate secured to the sides with angled iron, screws, and rivets, as you can see in the gun carriage template above. 

The carriages were designed to roll back and forth on iron rails attached to the floor of the turret. 

XI In. Gun Carriage in Turret of Monitor—arrangement of slides. (National Archives Identifier 149281934)

The Dahlgren guns mounted in the turret were 13 feet long, while the turret had an interior diameter of 20 feet. Controlling the significant recoil of the guns was a priority, since otherwise the guns would hit the back of the turret after firing. To solve this problem the Swedish-born engineer and inventor John Ericsson designed a friction braking mechanism, controlled by a large brass wheel that could tighten or loosen the braking assembly.

XI In. Gun Carriage in Turret of Monitor, showing the large brass wheel and brake. (National Archives Identifier 149281930)

According to the The USS Monitor Center at The Mariners’ Museum and Park in Newport News, Virginia, “One sailor wrote that during the initial test firing, the brake assemblies were accidentally loosened rather than tightened. When the guns fired each slammed into the rear wall of the turret leaving clear dents. Finding these dents on the shipwreck added archaeological evidence to support this account.”

The actual battle between the two ironclads was indecisive: despite fighting for several hours, neither was able to inflict significant damage on the other.

The Monitor foundered off Cape Hatteras during a storm on December 31, 1862. The wreck was rediscovered in 1973, and her gun turret, guns, gun carriages, and other parts of the ship were recovered in 2001–2002 through a joint effort between the U.S. Navy and the National Oceanic and Atmospheric Administration (NOAA). 

Raising the revolving gun turret during Phase II of the Monitor 2001 Expedition. (National Archives Identifier 6612094)

Artifacts from the Monitor are housed at the USS Monitor Center at the Mariners’ Museum and Park in Newport News, Virginia, a few miles from the site of her battle with CSS Virginia. Visitors to the museum can also see the original turret and other artifacts in the Batten Conservation Laboratory, where it is undergoing treatment in a large tank of water to prevent further corrosion of the metal.

2 thoughts on “USS Monitor Gun Carriages

  1. A very interesting article. I was unaware of the braking system used on the Monitor or of the museum. I will have go there when I am in the area. Thank you for the article.

  2. I have had the pleasure of corresponding with museum staff, and viewing some of the blueprints and Ericsson’s drawings.

    Neat little tidbit: Ericsson designed and patented a steam powered drill to bore out the firing holes in the turret, stumbled across that while researching if the firing holes were parallel to the gun barrels, or drilled perpendicular to the turret curve. Fascinating stuff.

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