Unlike the earlier vessels, Sfax carried an armor deck that covered her propulsion machinery and ammunition magazines.

Intended to be used as a commerce raider in the event of war with Great Britain, Sfax was rigged as a barque to supplement her engines on long voyages abroad.

During this period, she was primarily occupied with conducting training exercises; while in the Reserve Squadron, she was kept in commission for only part of the year.

The design for Sfax traces its origin to work the French naval engineer Louis-Émile Bertin prepared in 1870 for a new type of ironclad river monitors that incorporated a highly subdivided layer of watertight compartments intended to control flooding from battle damage.

[1] In 1878, the French Navy embarked on a program of cruiser construction authorized by the Conseil des Travaux (Council of Works) for a strategy aimed at attacking British merchant shipping in the event of war.

[2][3] The Director of Materiel, Victorin Sabattier, temporarily vacated his position in 1881 due to illness, and Bertin used the opportunity to protest the beginning of construction of Capitaine Lucas in light of developments in the Royal Navy; he was able to convince Sabattier's replacement, Alfred Lebelin de Dionne, that a version of his 1873 proposal would better suit French needs, and he in turn convinced the Minister of the Navy, Georges Charles Cloué, to cancel Capitaine Lucas in favor of Bertin's proposal.

Improvements suggested by the Conseil were incorporated into the ship, which was ordered in 1882, by which time Auguste Gougeard had replaced Cloué as the naval minister.

[4] Her hull featured a pronounced ram bow that was reinforced to allow it to bear the impact of colliding with another ship, along with short fore and sterncastles.

To supplement the steam engines on long voyages, she was originally fitted with a barque sailing rig with three masts.

[4][5] The power plant was rated to produce 7,680 indicated horsepower (5,730 kW) at 90 revolutions per minute for a top speed of 16 knots (30 km/h; 18 mph).

This provided a cruising range of 4,200 nautical miles (7,800 km; 4,800 mi) at an economical speed of 10.5 knots (19.4 km/h; 12.1 mph).

The deck was placed low in the ship, about 0.75 m (2 ft 6 in) below the waterline, with downward sloping sides that were reduced slightly in thickness to 28 mm (1.1 in).

Trials were completed on 7 June, when she was placed in full commission; eight days later she departed Brest for Toulon in the Mediterranean Sea.

She took part in that year's naval maneuvers, along with the ironclads Marengo, Océan, and Suffren, the torpedo cruiser Epervier, and several other vessels.

A series of exercises included shooting practice, a blockade simulation, and scouting operations in the western Mediterranean.

[15] In late January 1895, Sfax and the ironclad Amiral Duperré took part in an experimental bombardment of a simulated coastal fortification on Levant Island.

The French determined that an excessive amount of ammunition was required to neutralize the guns, and had the fortification been returning fire, both ships likely would have been seriously damaged.

These lasted from 18 to 21 July 1897, and the scenario saw the Sfax and Tage simulate a hostile fleet steaming from the Mediterranean Sea to attack France's Atlantic coast.

[4][23] In September 1898, after the work was completed, Sfax recommissioned and was assigned to the North American station, along with the unprotected cruiser Dubourdieu.

[24][25] After Alfred Dreyfus was pardoned that year, Sfax carried him back from Devil's Island in French Guiana to Port Haliguen.

Decommissioned on 13 August 1905 and then struck from the naval register in 1906, Sfax was used as a storage hulk for shells and propellant charges from 1906 to 1909.