USS Dunderberg

The steam ram Dunderberg, Harper's Weekly, 1867
History
United States
Name	Dunderberg
Namesake	Swedish: "thunder(ing) mountain"
Ordered	3 July 1862
Builder	William H. Webb, New York City
Laid down	by 3 October 1862
Launched	22 July 1865
Fate	Not accepted by U.S.N. Sold to France by 7 May 1867
France
Name	Rochambeau
Namesake	Comte de Rochambeau
Acquired	by 7 May 1867
Commissioned	7 August 1867
Renamed	7 August 1867
Stricken	15 April 1872
Fate	Scrapped, 1874
General characteristics (in French service, 1868)
Type	Casemate ironclad
Displacement	7,849 metric tons (7,725 long tons)
Length	107.4 m (352 ft 4 in) (p/p)
Beam	22.15 m (72 ft 8 in)
Draft	6.5 m (21 ft 4 in) (mean)
Depth	7.078 m (23 ft 2.7 in)
Installed power	4,000 PS (2,900 kW) 6 Tubular boilers
Propulsion	1 shaft, 2 Horizontal back-acting steam engines
Sail plan	Brigantine rig
Speed	14.5 knots (26.9 km/h; 16.7 mph)
Range	2,200 kilometres (1,200 nmi) at 8 knots (15 km/h; 9.2 mph)
Complement	600
Armament	4 × 1 – 274 mm (10.8 in) Mle 1864/66 guns 10 × 1 – 240 mm (9.4 in) Mle 1864/66 guns
Armor	Waterline belt: 90–70 mm (3.5–2.8 in) Deck: 18 mm (0.7 in) Casemate: 120 mm (4.7 in) Conning tower: 250 mm (9.8 in)

Dunderberg, which is a Swedish word meaning "thunder(ing) mountain",^[1] was an ocean-going casemate ironclad of 14 guns built for the Union Navy. She resembled an enlarged, two-masted version of the Confederate casemate ironclad CSS Virginia. She was originally designed to have both gun turrets and a casemate but the turrets were deleted while the ship was still being built. Construction began in 1862, but progress was slow and she was not launched until after the end of the American Civil War in 1865.

The ship was not accepted by the Union Navy so her builder began seeking buyers elsewhere; Otto von Bismarck expressed some interest, and the thought of Prussia armed with such a vessel prompted France to purchase her and commission her in 1867 with the name Rochambeau. She was initially placed in reserve, but was mobilized in 1870 to participate in the Franco-Prussian War. The ship saw no action and was decommissioned after the end of the war. Rochambeau was stricken from the Navy Directory in 1872 and scrapped in 1874.