Tilsitt was a steam-powered, third-rate, 80 gun built for the French Navy during the 1850s. She had been laid down as a sailing ship of the line in 1832, but remained on the stocks until the ship was launched in 1854 and completed later the same year. Tilsitt played a minor role in the Crimean War of 1854âÂÂ1855. The ship was chosen for conversion to steam power in 1854.
Tilsitt had a length of at the gun deck a beam of and a depth of hold of . The ship displaced 4289 tonnes and had a mean draught of . Her crew numbered 814 officers and ratings. She was powered by a horizontal-return connecting rod-steam engine that drove the single propeller shaft. The engine, built by Arsenal de Brest, was rated at 500 nominal horsepower. She was fitted with three masts and ship rigged like the 80-gun sailing ships of the line in service.
The muzzle-loading, smoothbore armament of Breslaw consisted of sixteen 36-pounder long guns and fourteen Paixhans guns on the lower gun deck. On the upper gundeck were twenty-four 30-pound short guns. On the quarterdeck and forecastle were a total of two rifled guns, a dozen 30-pounder short guns, and six 30-pounder carronades.
Tilsitt had been laid down as a 90-gun 3rd-rank on 20 August 1832 at the Arsenal de Cherbourg under the name of Diomède, but construction was suspended. The ship was renamed Tilsitt on 23 November 1839. Her incomplete hull was kept in a covered slipway until she was launched on 30 March 1854. The ship was commissioned on 20 May 1854 and completed in June. Breslaw served as a troopship during the Crimean War.
The ship's conversion into a steam-powered ship was ordered on 19 October 1854, although work did not begin until 9 February 1856 at the Arsenal de Brest. Tilsitt was re-launched later that year, completed in October 1859 and recommissioned on 1 January 1860. She served as a troopship during the French intervention in Mexico in 1862âÂÂ1863 before becoming a prison hulk for prisoners of the Paris Commune.