USA Naval History: The USS Monitor

The USS Monitor was the first ironclad war ship in the American Civil War. The American Civil war, which lasted from 1861 to 1865, was the conflict between the North (Union) and South (Confederate). Designed by the Swedish-American engineer, John Ericsson, the USS Monitor was built in118 days. The ship had a number of innovative features and could withstand the rigors of naval battles. In the Battle of Hampton Roads on March 9, 1862, the USS Monitor successfully defended Union ships from the attack of the CSS Virginia, the Confederates ironclad battleship.

The Battle of Hampton Roads changed the nature of naval warfare with the introduction of the ironclad warship. It marked the transformation of war vessels from wood and sail to iron and steam. The USS Monitor started a long line of USS Monitor Class U.S. warships and the generic term "monitor", which refers to a broad class of European harbor defense craft.

Constructing the First Ironclad Warships

Various designs were presented and reviewed by the Naval Board; but it was the USS Monitor, designed by John Ericsson, which was unanimously selected. Congress finally authorized the ship’s construction in July 1861. The USS Monitor was smaller in dimension compared to CSS Virginia. Nine different foundries were commissioned to fabricate its parts. Iron fabrication started even before the USS Monitor's contract was released in early October. Ironworkers had to build fast to compete with the Confederate during naval battles using the CSS Virginia.

The construction of USS Monitor began on October 25, 1861 and was completed on January 30, 1862. The Continental Iron Works in Greenpoint, Long Island, New York constructed the hull of the ship, while other companies provided the iron stock, machinery and other equipment. DeLamater Iron Works in Manhattan, New York built the steam engines and machinery used on the ship and a forge in Clinton, New York supplied parts of the vessel’s heavy iron plating. 

The cost of constructing the ship was between the amounts of $270,000 to $280,000. Its dimension in length was 172'; its beam was 41' 6" and its depth was 11' 4". The engines were double trunk, cylinders (2 in 1 casting) 36" diameter, 27" stroke. There were two return tube box boilers. Built to withstand naval battles, all protective devices were provided for in this battle ship.

  • American Civil War – Has general resources, documentary records and other vital information about the Civil War.
  • Duel between the Ironclads – Narrates the naval battle between the ironclads: the CSS Virginia and USS Monitor

Designing the USS Monitor

The deck of the USS Monitor was installed with a 25-foot iron thickly armored round turret that used steam power to rotate. The turret held a couple of 11-in. (280 mm) Dahlgren guns placed beside each other. The turret had eight layers on an inch plate, wielded together with a ninth plate inside to act as a sound protection. It was moved by a steam donkey engine. Aside from the turret, the USS Monitor was provided with Ericsson's new marine screw, which ran the battle ship on steam propulsion.

The heavily armored deck was 5/8-inches thick, but it stretched beyond the waterproof hull. There were a small box-like pilothouse, a movable smokestack and some fittings. The weak parts of the vessel were well protected, as it was proven in the Battle of Hampton Roads. The bullets from CSS Virginia just bounced off the turrets and deck of the USS Monitor; they dented the parts, but never caused major damaged.

The interior part of the ship had oak planks covered with iron plates. Each iron plate measured ½-inch thick. The upper area and hull of the ship were enclosed with iron. All over the vessel, a 5-inch iron encased the wood. This battle ship appeared like a submarine but functioned as a ship. The USS Monitor was forerunner as a naval architecture; the design of the USS Monitor became the model of other battle ships constructed after the Civil War.

Clash Between Two Ironclads & the Battle of Hampton Roads

The Battle of Hampton Roads was one of the most pivotal battles fought during the Civil War. On March 8, 1862, CSS Virginia, formerly the USS Merrimack, assaulted the Union squadron who set up a blockade along Jones River, Hampton Roads. Virginia defeated two Union vessels, the Cumberland and Congress. Earlier, Minnesota attempted to attack Virginia, but it ran aground; however, Virginia discontinued her attack for it was getting dark.

The USS Monitor, under Lieutenant John L. Worden, was ordered to intercept the Virginia before it returned to finish off the Minnesota. What followed was the clash of two ironclads. The Virginia tried to crush into USS Monitor, but her blow did not penetrate USS Monitor’s body. It worsened the damage of Virginia’s bow, which was almost wrecked from her previous encounter with Cumberland. On the other hand, USS Monitor was unable to do much harm to Virginia, because Cmdr. John Dahlgren, the gun’s creator, commanded a reduction of gun charges. 

Finally, the Virginia’s canon struck the pilothouse of USS Monitor. Lt. Worden. Suffering from an eye injury due to the explosion, Lt. Worden piloted the ship towards shallow water. The executive officer, Samuel Greene, considered the damage serious, but he directed USS Monitor to continue the battle.

The Virginia decided to attack the Minnesota, but she could not get closer for it was low tide. Her officers decided to go back to Norfolk, Virginia to fix the damage. The USS Monitor did not chase the Virginia, staying in place to protect the Minnesota.

The USS Monitor was able inflict considerable damage on the Virginia and defended the Minnesota, and the entire Union fleet, from the Confederate navy. The outcome of the battle did not turn the tide of war; the Union still dominated Hampton Roads, while the Confederates controlled several rivers and Norfolk, Virginia.

The fate of the USS Monitor was tragic. On December 31, 1862, the USS Monitor floundered and sank off the Coast of Cape Hetteras in North Carolina.

Historical Impact

The clash between the two ironclads, the USS Monitor and CSS Virginia, in the Battle of Hampton Roads marked the initial combat between war vessels whose hulls were protected with iron plates. The confrontation served as a turning point for it ended the age of the wooden war vessels. Iron and cased ships started replacing wooden combat ships. The USS Monitor became the standard model for warships. The Battle of Hampton Roads got the attention of the world and greatly affected naval defenses for they realized the importance of having invulnerable weapons.

It started the USS Monitor mania, when the world’s great powers realized their vulnerability and started building ships according to the USS Monitor prototype. Great Britain and France, who were leaders in shipbuilding, ceased all constructions of their wooden cruisers and replaced the design based on the USS Monitor model. The United States initiated the building of more ironclad ships.

The USS Monitor was indeed one of the most successful prototypes in ship’s history.


Today, remnants of the USS Monitor lay on the sea floor off North Carolina's Outer Banks, where the ship floundered due to the storm of December 31, 1862. The USS Monitor is considered, not only as a symbolic object of Civil War History, but also as a turning point of defense in the International Naval History.

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