USS Monadnock (BM-3) crossing the Pacific Ocean in 1898; note how the ship is swamped due to the low-freeboard typical of monitors
Ships of the
United States Navy
Ships in current service
Ships grouped alphabetically
Ships grouped by type

This is a list of all monitors of the United States Navy. While the most famous name is represented in this list, many monitors held multiple names during their service life. View the complete list of names.

Historical overview

The whole category of monitors took its name from the first of these, USS Monitor, designed in 1861 by John Ericsson. They were low-freeboard, steam-powered ironclad vessels, with one or two rotating armored turrets, rather than the traditional broadside of guns. The low freeboard meant that these ships were unsuitable for ocean-going duties and were always at risk of swamping and possible loss, but it reduced the amount of armor required for protection.

They were succeeded by more seaworthy armored cruisers and battleships.

River monitors

Further information: River monitor

Neosho-class monitors

The river monitor Neosho.

Main article: Neosho-class monitor

Marietta-class monitors

Main article: Marietta-class monitor

Harbor monitors

Casco-class monitors

Casco-class monitors Shawnee and Wassuc.

Main article: Casco-class monitor

Coastal monitors

The Monitor, prototype for an entire class of warship.

Monitor-class monitor

Passaic-class monitors

Main article: Passaic-class monitor

Canonicus-class monitors

Main article: Canonicus-class monitor

Milwaukee-class monitors

Main article: Milwaukee-class monitor

Seagoing monitors

The original Puritan.

Miantonomoh-class monitors

Main article: Miantonomoh-class monitor

Kalamazoo-class monitors

Main article: Kalamazoo-class monitor

"New Navy" monitors

See also: History of the United States Navy § "New Navy"

The first five of these were ostensibly rebuilds of Civil War era monitors (in much the same way that the 1854 sloop-of-war Constellation was ostensibly a refit of the 1797 sail frigate Constellation). In fact, they were entirely new ships, much larger and more capable than the previous ones. Dates listed are the first commissioning dates.

The "refit" Puritan.

Puritan-class monitors

Amphitrite-class monitors

Main article: Amphitrite-class monitor

Monterey-class monitors

Arkansas-class monitors

Main article: Arkansas-class monitor

USN "Brown Water Navy" (Vietnam War) Monitors

The US Navy created their first Mobile Riverine Force (MRF) for the first time since the American Civil War, during the Vietnam War. World War II all steel 56-foot (17 m)-long Landing Craft Mechanized (LCM-6s) were used as the basic hull to convert into 24 Monitors from 1966-1970. This was a separate US Navy Mobile Riverine Force from the Swift Boats (PCFs) and PBRs already operating in country.[1]: 10, 11  The twenty-four river Monitors were divided into two groups: Program 4 & 5. Ten Program 4 Monitors arrived first in Vietnam, and were armed with one 40mm cannon mounted inside a revolving Mk 52 turret; while the 8 later arriving Program 5 versions (designated Monitor "H") mounted one M49 105mm Howitzer inside a revolving T172 turret.[1]: 27  Due to a shortage of M49 howitzers,[1]: 82  the USN converted the remaining six Program 5 Monitors (designated Monitor "F") to Flamethrower Monitors, and equipped them with an M10-8 flamethrower mounted inside an M8 cupola turret. The early Program 4 Monitors had hull numbers reflecting their River Assault Division (RAD) as well as their hull number. Later, simply the hull numbers were used, such as M-1 (Monitor 1), A-1 (Alpha Boat 1), C-1 (Command/Communications/Control 1), etc.

River Assault Flotilla One Program 4 Monitors (40mm cannon)

River Assault Flotilla One Program 5 Monitors (105mm Howitzer) & (Flamethrower)

Similar vessels of interest

The Keokuk.


  1. ^ a b c d e f g h i j Carrico, John M (2007). Vietnam Ironclads, A Pictorial History of US Navy River Assault Craft, 1966-1970. Brown Water Enterprises. ISBN 978-0-9794231-0-9.
  • Friedman, Norman (1987). US Small Combatants: An Illustrated Design History. US Naval Institute Press. ISBN 0-87021-713-5.
  • Konstam, Angus (2002). Union River Ironclad 1861-65. New Vanguard 128. Oxford: Osprey Publishing. ISBN 978-1-84176-444-3.
  • Roberts, William O. (2002). Civil War ironclads: the U. S. Navy and industrial mobilization. Baltimore: Johns Hopkins University Press. ISBN 0-8018-6830-0.
  • Rottman, Gordon (2006). Vietnam Riverine Craft 1962-75. New Vanguard 128. Oxford: Osprey Publishing. ISBN 978-1-84176-931-8.