U.S.S. Monitor (1862)

Painting of the MONITOR at sea

Intro - read on.    |    Specifications    |    Battle Pictures    |   Battle Description    |   Wreck    |    Links

The Monitor was the first-ever turret ship -- an ironclad Civil War gunboat entirely designed by Swedish-American inventor Jon Ericsson. His most remarkable invention was the revolving gun turret (diagram, below) which -- combined with the complete absence of deck structures to restrict the guns' arc of fire -- allowed guns to be trained to any quarter no matter what direction the ship was pointed. The ship was intended as a harbor defense vessel. With her very low freeboard -- she was nearly a submarine -- and flat bottom, the Monitor was not very seaworthy, but after being towed there from New York, she did fight one landmark battle with the Confederate ironclad Virginia at Hampton Roads, Virginia in March 1862. This action was fought under the command of Lt. John L. Worden, who much later made Rear Admiral and became the seventh Superintendent of the U.S. Naval Academy. His service in the Monitor those white-knuckled days in '62 was remembered, as were his wounds -- he was temporarily blinded by a direct hit on the pilothouse during the action with Virginia.
Cross section of the MONITOR's turret
Built entirely of iron, she consisted of a one-deck, flat-bottomed hull with an armored raft attached to the top and sides. Beside the turret, her deck was broken by a cubical pilot house forward, a well for the patent anchor near the bow, and square holes for the blowers and exhaust, aft of the turret. The Monitor's turret bore the earmarks of a new invention. Nine feet tall and 20 in diameter, it spun on a central spindle to position the guns for firing. The two 11-inch Dahlgren smoothbores had to be drawn into the interior for reloading after each firing; armored shutters swung into place to close the muzzle apertures in the turret wall, armored with 8" iron plate. The guns could only fire one at a time, and the entire turret had to be jacked up in order to rotate, then re-settled on the deck for firing. This made the rate of fire slow; yet gun crews toiling inside were relatively safe. Ordinary shells of the day might inflict at most a dent as they ricocheted off the ship's armor plate, although the crews inside reported loud ringing and intense vibration as projectiles hit and bounced off. The slow rate of fire -- one shot every four minutes -- made old Navy admirals impatient. Designed as a port defense ship, Monitor did not fit the bill very well when commandeered for offensive operations, such as bombarding land fortifications. Click to enlarge diagram at right.

For the propulsion plant, Ericsson faced a real design challenge. To move the heavy armored bulk of the ship, he needed the power of a trunk engine, but the space available was only half that required. Moreover, a trunk engine would create an imbalance in weight distribution for which would be impossible to compensate in such a small vessel. Ericsson's solution was an elaborate variation on the trunk engine, with two balanced horizontal cylinders indirectly driving a central shaft -- an arrangement patented as the Ericsson vibrating lever engine.    Diagram    Video

Plans and Specifications

Original plans of the MONITOR

Original plans for the ship, published 1862. Enlarged view
Specifications for the Monitor: Length: 172'. Beam: 41'6". Draft: 10'6". Displacement: 987 tons. Armament: (2) 11" Dahlgren smoothbores. Armor: 8" laminated iron plates (turret), 4" hull, 1" deck. Propulsion: (2) coal-fired fire-tube boilers. (2) 2-cyl Ericsson vibrating lever steam engines each developing 320 IHP, single shaft; Ericsson patent screw. Speed: 7 knots.

Metric Specs:
Dimensions: 52m x 12.6m x 3.2m   Displacement: 987 tons. Armament: (2) 28 cm Dahlgren smoothbores. Armor: 203 mm laminated iron plates (turret), 102 mm (hull), 25 mm (deck). Propulsion: (2) coal-fired fire-tube boilers. (2) 2-cyl Ericsson vibrating lever steam engines each developing 238.6 kW, single shaft; Ericsson patent screw. Speed: 13 km/hr.

Profile Plan of the MONITOR

Turret cutaway of the MONITOR

Pictured above by Joe Hinds, the ship was a tour-de-force of Ericsson inventions and scored many historic firsts. The revolving turret was the first of its kind, although a similar unit was produced at almost exactly the same time by Royal Navy Capt. Cowper Coles. The two designs would remain in competition for the next quarter century. Initially the turret was roofed by a metal grating and open to the air. Later models of Civil War monitor almost all had circular armored pilothouses installed on top of their turrets.

Profile Plan of the MONITOR
Rudder and screw of the Monitor.

Profile Plan of the MONITOR
Launch of the Monitor.

Despite its trailblazing design and engineering, the ship had serious drawbacks as a floating home. Ventilation was so poor that the summer temperature below decks averaged a sweltering 120 degrees F; engine-room readings up to 178 F were recorded routinely through 1862. These drawbacks were duly copied in the dozens of derivative craft built in succeeding years: four for the Swedes, fourteen for the Russians, three for the Danes, two for Holland, and three similar batteries for Britain, as well as 49 monitors of various kinds for the Union. Because of her low freeboard -- mere inches at the edges of the deck -- the Monitor was hazardous in any kind of seaway; waves threatened to douse the fires and wash down the ventilator shaft even after tall pipes had been installed to circumvent this problem.

The Battle of Hampton Roads

Battle of Hampton Roads
The ironclads slugging it out at Hampton Roads -- painting by J.O. Davidson.

Battle of Hampton Roads
The battle depicted by R.C. Moore. Enlarge

Battle of Hampton Roads - Chart
The battleground at Hampton Roads.

Text describing the battle

Profile Plan of the MONITOR
The scene inside the turret during the battle with the Virginia.

Battle of the MONITOR and VIRGINIA, dramatic close-up view
Close in view of the action: Late 19th-century woodengraving, showing the Virginia's stern awash.


Ridiculed as a "cheesebox on a raft" by the sticks-and-strings sailors of the Old Navy, the pioneering Monitor nevertheless proved an influential design long after sails and wooden hulls had been abandoned by the world's navies. The little Monitor was the progenitor of the behemoth battleships that sparked naval rivalries leading up to the two World Wars; although it took decades for a balanced, seaworthy design to be hit on with the pre-dreadnoughts of the 1890s. More immediately, the ship's success in resisting the Virginia led to a building spree in the North. Ten improved monitor-type vessels were ordered from Ericsson within weeks of the battle. Subsequent orders included twin-turreted and triple-turreted monitors. In all, 64 of the 84 ironclads built for the Union Navy during the Civil War were variants of the Monitor type. Some of the versions built by inventor and entrepreneur James B. Eads included a steam-powered turret with guns that dropped to a lower deck to reload, then elevated back into the turret to assume firing position. While the Ericsson system turret predominated in the United States (largely due to obsessive legal pressure from Ericsson himself), a rival turret system invented by Capt. Cowper Coles of the Royal Navy was the preferred type in the British fleet, being developed and first deployed during precisely the same period. In the Russian navy, which tried both, Ericsson's design triumphed. At exactly the time American shipyards were going crazy trying to fill the Federal government's orders, Russia built a class of ten monitors to U.S. design: the Uragan class, armed with Dahlgren cannon. The inventor's native Sweden indulged him by purchasing a flotilla of Passaic-style monitors in the late 1860s.

USS MONITOR - watercolor by Oscar Barros
Oscar Barros pictures the Monitor with the wooden frigates at Hampton Roads. Enlarge

Deck scene on the MONITOR, post battle

A deck scene after the battle, showing the dents caused by point-blank Confederate hits. Photographed by James F. Gibson on the James River, Virginia, July 9, 1862. Wet collodion glass negative, left half of stereo pair. Click here to enlarge.

Wreck of the Monitor

Painting of the MONITOR sinking at night, in high seas

The Monitor sinks in heavy weather as the escort steamer Rhode Island takes off her crew. Painting by Tom Freeman.


In 1974, the Monitor's wreck was discovered off Cape Hatteras, where it sank while under tow in a storm December 31, 1862. After 112 years' immersion, the vessel lay upside down on the bottom, heavily covered with marine growth, her turret dislodged beneath the hull. Monitor's patent Ericsson screw propeller was detached and brought to the Mariners' Museum in Newport News, Virginia, near Hampton Roads; on Aug. 5, 2002 the famous gun turret, complete with its two Dahlgren "soda bottle" guns and a great deal of silt, was salvaged intact. Plans are afoot to raise the entire wreck and preserve it at the Mariners' Museum, though the advanced deterioration of the hull poses steep problems for the would-be salvors. At least, the turret and guns, engine, propeller, and condenser were on exhibit when the Museum's USS Monitor Center opened in 2007. Visitors can get a feel for the tight spaces within by clambering around a life-size replica of the ship, donated by Northrup Grumman Norfolk.

This has been a truly remarkable marine archaeology project, bringing a groundbreaking historic ship back to public access. Together with the Cairo, the Neuse, and the Hunley, Monitor completes a grand quartet of Civil War vessels, all lost in war and reclaimed much later. Along with the Constitution, Constellation, Olympia and Texas, they illustrate the sweep of naval development from the founding of the Republic through World War I. And no nation is better found in World War II battleships than the U.S. -- all of them overgrown descendants of the Monitor and her generation of ironclad turret ships.

Relevant Weblinks