Military Wiki
Casco-class monitor
USS Casco
USS Casco on the James River, 1865
Class overview
Name: Casco-class light draft monitor
Builders: Various
Operators: United States Navy
Preceded by: Passaic-class
Completed: 20
Retired: 20
General characteristics
Displacement: 1,175 tons
Length: 225 feet
Beam: 45 feet
Draught: 6 feet (designed)
Propulsion: Steam engine, twin screws
Speed: 8 knots (designed)
Armament: 2 x 11-inch (280 mm) guns

The Casco-class monitor was a unique class of light draft monitor built on behalf of the United States Navy for the Mississippi theatre during the American Civil War. The largest and most ambitious ironclad program of the war, the project was dogged by delays caused by bureaucratic meddling. Twenty ships of the class were eventually built at great expense, but proved so unseaworthy when trialed that they were quickly sidelined, causing a public scandal.


After the success of the US Navy's first monitor, the USS Monitor, in preventing the Confederate ironclad CSS Virginia from breaking the Union blockade at Hampton Roads in the spring of 1862, the navy became enthused with the monitor concept (at the expense of the larger broadside ironclad type), and ordered a number of new classes of monitor, one of which was the Casco class.[1] The Casco was a unique "light draft" class designed specifically for operating in the shallow bays, rivers, and inlets of the Confederacy.[2]

The specifications for the Casco class originally called for a vessel with a light draft, not exceeding six feet, and a low freeboard]] to present the smallest possible target to Confederate guns. For the design of the new class, the Navy turned once again to John Ericsson, designer of the USS Monitor. [[File:Uss Nausett 1865.jpg|thumb|250px|Diagram of the USS Nausett, showing the large wooden "raft" surrounding the iron hullEricsson came up with a design for a 225-foot (69 m)-long vessel with a single revolving turret containing two 11-inch (280 mm) guns, an armored upper deck, and twin screw propellers giving a top speed of around eight knots. Around the hull of the vessel, a large wooden "raft" was to be constructed, which would help increase buoyancy. Ericsson kept the design deliberately simple in keeping with the inexperience of the private shipyards which would be called upon to build them.[3] He anticipated that each ship would take no more than forty days to complete.[4]

The monitor office

At around the same time however, the Navy created a new "monitor office" to centralize oversight of the new monitor program. The new office, located across the hall from Ericsson's design bureau, was nominally headed by Rear Admiral Francis H. Gregory, but was effectively run by Chief Engineer Alban C. Stimers, to whom was entrusted the power of setting general plans and ship specifications. Stimers, an ambitious man, was keen to take credit for the design of the new monitors and frequently visited Ericsson's bureau to make changes to the specifications.[3][5]

The greatest single alteration to the design however, came not directly from Stimers but from Admiral Joseph Smith, chief of the Bureau of Yards and Docks in Washington, D.C., who suggested that the oval hull of the ship be surrounded by large iron tanks which could be pumped full of water in order to lower the ship's freeboard still further when in combat to present an even smaller target, or drained for normal travel. Stimers liked the idea and ordered the changes, but when Ericsson saw the new plans he resigned from the project. The new plans greatly added to the design's complexity, requiring sophisticated pumping mechanisms, while the added weight would also reduce speed and buoyancy.[4]

More design changes

In February 1863 the monitor office offered contracts for twenty of the new Casco-class monitors, in spite of the fact that the original architect, Ericsson, had not approved the new design. Winning bidders included prominent firms like Reaney, Son & Archbold in Chester, Pennsylvania, Wilcox & Whitney at Camden, Harlan & Hollingsworth in Wilmington, Delaware and Merrick & Sons of Philadelphia (the latter of whom subcontracted much of the work to William Cramp & Sons). A number of smaller firms were also contracted. The cost was estimated at $395,000 per ship, or approximately $8 million in total. Some shipyards, such as Cramp, were forced to substantially upgrade their ironworking facilities for the production of the new vessels.[6]

Detail drawing by Stimers for one of the Casco-class monitors

By the end of 1863, frequent design changes were causing growing problems for the contractors. Stimers and his team of thirty draftsmen at the monitor office continued to submit changes even as the vessels were in the process of production, leading to long delays. One yard in Boston received a total of 83 drawings and 120 letters of explanation from Stimers, and the specification manual for the ships grew to 92 pages of small print.[7] The final design called for a total of thirteen auxiliary engines and pumps per ship, fancy brasswork in place of cast iron, and a complex system of pipes for draining and filling the water tanks. The added weight to a ship designed with only a 15-inch (380 mm) freeboard at the outset raised questions about the ships' eventual seaworthiness.[8]

Scandal and inquiry

By spring of 1864, the first of the Casco class vessels, the USS Chimo, was ready for her initial trial. Putting to sea, waves washed across the deck, while the stern remained totally submerged by three or four inches (10 cm).[9] A second trial, of the USS Tunxis, confirmed the disaster, with waves washing over the deck and the ship only able to make a speed of 3½ knots as opposed to the original specification of eight. Moreover, the trials were conducted "light", without the normal operational loads of coal, ammunition and stores. The ships were unseaworthy and virtually useless.[8][10][11]

By this stage, the twenty vessels, in various stages of completion, had cost half a million dollars apiece. Amid public scandal, the Navy set up an inquiry. Stimers was found responsible and removed from his post, and the Navy appointed experienced administrators in his place. The vessels were redesigned and refitted in order to improve buoyancy, but few of them saw active service before the end of the war and those that did were decommissioned and laid up within months, while the majority were never commissioned at all. Within a few years, all the ships of the Casco class had been retired and scrapped or otherwise disposed of.[12]


Ship Builder Contracted Launched *Commissioned
Turret removed? Renamed Fate
USS Casco Atlantic Iron Works, Boston, Massachusetts 14 April 1865 7 May 1864 *4 December 1864 Yes Hero, 15 June 1869 Scrapped, 1875
USS Chimo Aquilla Adams, South Boston, Massachusetts 17 May 1863 5 May 1864 *20 January 1865 Yes Orion, 15 June 1869
Piscataqua, 10 August 1869
Sold for scrap, 1874
USS Cohoes Continental Iron Works, Brooklyn, New York 17 April 1863 31 May 1865 **19 January 1866 No Charybdis, 15 June 1869
Cohoes, 10 August 1869
Sold for scrap, July 1874
USS Etlah Charles W. McCord, St. Louis, Missouri 24 June 1863 3 July 1865 **12 March 1866 No Hecate, 15 June 1869
Etlah, 10 August 1869
Sold for scrap, 12 September 1874
USS Klamath Alexander Swift, Cincinnati, Ohio 26 March 1863 20 April 1865 **6 May 1866 No Harpy, 15 June 1869
Klamath, 10 August 1869
Sold for scrap, 12 September 1874
USS Koka Wilcox & Whiting, Camden, New Jersey 24 April 1863 18 May 1865 **28 November 1865 No Argos, 15 June 1869
Koka, 10 August 1869
Sold for scrap, 2 October 1874
USS Modoc J.S. Underhill, Brooklyn, New York 4 June 1863 21 March 1865 **23 June 1865 Yes Achilles, 15 June 1869
Modoc, 10 August 1869
Sold for scrap, August 1875
USS Napa Harlan & Hollingsworth, Wilmington, Delaware 2 March 1863 26 November 1864 **4 May 1866 Yes Nemesis, 15 June 1869
Napa, 10 August 1869
Sold for scrap, 1875
USS Naubuc Union Iron Works, Brooklyn, New York 2 April 1863 19 October 1864 *27 March 1865 Yes Aetna, 15 June 1869
Minnetonka, 10 August 1869
Sold for scrap, 1875
USS Nausett Donald McKay, Boston, Massachusetts 10 June 1863 26 April 1865 *10 August 1865 No Achilles, 15 June 1869
Nausett, 10 August 1869
Sold for scrap, August 1875
USS Shawnee Curtis & Tilden, Boston, Massachusetts 2 April 1863 13 March 1865 *18 August 1865 No Eolus, 15 June 1869
Shawnee, 10 August 1869
Sold for scrap, 9 September 1875
USS Shiloh Charles W. McCordat, St. Louis, Missouri 24 June 1863 14 July 1865 **12 March 1866 No Iris, 15 June 1869
Shiloh, 10 August 1869
Sold for scrap, 1874
USS Squando Donald McKay, Boston, Massachusetts 4 May 1863 31 December 1864 *6 June 1865 No Erebus, 15 June 1869
Algoma, 10 August 1869
Scrapped, 1874
USS Suncook Globe Works, South Boston, Massachusetts 17 March 1863 1 February 1865 *27 July 1865 No Spitfire, 15 June 1869
Suncook, 10 August 1869
Scrapped, July 1874
USS Tunxis Reaney, Son & Archbold, Chester, Pennsylvania 9 March 1863 4 June 1864 *12 July 1864 No Hydra, 15 June 1869
Otsego, 10 August 1869
Sold for scrap, 1874
USS Umpqua Snowden & Mason, Brownsville, Pennsylvania 4 March 1863 21 December 1865 **7 May 1866 No Fury, 15 June 1869
Umpqua, 10 August 1869
Sold for scrap, 12 September 1874
USS Wassuc George W. Lawrence, Portland, Maine 2 June 1863 25 July 1865 **28 October 1865 No Stromboli, 15 June 1869
Wassuc, 10 August 1869
Sold for scrap, 9 September 1875
USS Waxsaw A. & W. Denmead & Son, Baltimore, Maryland 13 March 1863 4 May 1865 **21 October 1866 No Niobe, 15 June 1869
Waxsaw, 10 August 1869
Sold for scrap, 25 August 1875
USS Yazoo William Cramp and Sons, Philadelphia, Pennyslvania 2 March 1863 8 May 1865 **15 December 1865 No Tartar, 15 June 1869
Yazoo, 10 August 1869
Sold for scrap, 5 September 1874
USS Yuma Alexander Swift, Cincinnati, Ohio 26 March 1863 30 May 1865 **6 May 1866 No Tempest, 15 June 1869
Yuma, 10 August 1869
Sold for scrap, 12 September 1874


  1. Heinrich, pp. 42–43.
  2. USS Umpqua, DANFS Online.
  3. 3.0 3.1 Roberts, p. 110.
  4. 4.0 4.1 Heinrich, p. 44.
  5. Heinrich, p. 43.
  6. Heinrich, p. 44-45.
  7. Roberts, p. 116.
  8. 8.0 8.1 Heinrich, p. 47.
  9. Roberts, p. 159.
  10. Roberts, p. 160.
  11. Alban C. Stimers, DANFS
  12. Heinrich, p. 48. See also DANFS entries for the individual ships below.


  • Canney, Donald L. (1993). The Old Steam Navy: The Ironclads, 1842–1885. 2. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-586-8. 
  • Chesneau, Roger; Kolesnik, Eugene M., eds (1979). Conway's All the World's Fighting Ships 1860–1905. Greenwich, UK: Conway Maritime Press. ISBN 0-8317-0302-4. 
  • Heinrich, Thomas R. (1997): Ships for the Seven Seas: Philadelphia Shipbuilding in the Age of Industrial Capitalism, Johns Hopkins University Press, ISBN 0-8018-5387-7, pp. 42–48.
  • Olmstead, Edwin; Stark, Wayne E.; Tucker, Spencer C.. The Big Guns: Civil War Siege, Seacoast, and Naval Cannon. Alexandria Bay, New York: Museum Restoration Service. ISBN 0-88855-012-X. 
  • Roberts, William H. (2002): Civil War Ironclads: Industrial Mobilization for the US Navy 1861–1865, Johns Hopkins University Press, ISBN 0-8018-6830-0
  • Silverstone, Paul H. (1984). Directory of the World's Capital Ships. New York: Hippocrene Books. ISBN 0-88254-979-0. 
  • Silverstone, Paul H. (2006). Civil War Navies 1855–1883. The U.S. Navy Warship Series. New York: Routledge. ISBN 0-415-97870-X. 

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