After the Italian Navy began building a series of very large ironclads in the mid-1870s, public pressure on the French naval command to respond in kind prompted the design for the Amiral Baudin class.

Begun in 1879, work on the ships proceeded slowly and they were not finished until 1888–1889, shortly before the first pre-dreadnought battleships began to be built, which rendered older ironclads like the Amiral Baudin class obsolete.

By that time, the Italian Regia Marina (Royal Navy) had begun its own expansion program under the direction of Benedetto Brin, which included the construction of several very large ironclad warships of the Duilio and Italia classes, armed with 450 mm (17.7 in) 100-ton guns.

At the time, the gun was seen as the primary weapon at sea, since the previously favored tactic of ramming an opponent had been rendered less feasible by the invention of self-propelled torpedoes.

The Inspector General of Artillery submitted a report to the French Naval Minister, Léon Martin Fourichon, on 20 November 1876 that recommended a 120-ton gun with a bore diameter of around 440 mm (17 in), which would be able to penetrate the thickest armor then in production.

French designers differed from their Italian counterparts, opting to retain a complete albeit narrow waterline armor belt instead of Brin's solution, the citadel system supported by a closely compartmentalized layer.

[4] On 19 January 1878, Louis Pierre Alexis Pothuau, who had succeeded Fourichon as naval minister in 1877, issued a request to shipyards in Brest and Lorient for designs for a new first-rank ironclad armed with either 75-ton or 100-ton guns.

[6] During a meeting on 30 July, the Conseil des Travaux evaluated several designs and selected the one presented by the naval engineer Charles Godron.

Godron completed his revised design on 6 November and submitted them to the Director of Material, Sabattier, who in turn presented in to Pothuau on 13 December.

[10] The Amiral Baudin design proved to be successful and led to the derivative ironclad Hoche and three-ship Marceau class.

[4] The ships' period as state-of-the-art capital proved to be very brief; they were completed in 1888 and 1889, just before Britain passed the Naval Defence Act of 1889, authorizing the Royal Sovereign class of what would become known as pre-dreadnought battleships.

The French in turn responded with their Naval Law of 1890, laying down a series of experimental pre-dreadnoughts beginning with Charles Martel that year.

The hull featured a pronounced tumblehome shape common to French capital ships of the period, and they incorporated a ram bow.

The ships were difficult to maneuver and they rolled badly in service, particularly in a beam sea, making them poor gun platforms.

[13][14] The ships' propulsion machinery consisted of a pair of two-shaft, vertical compound steam engines that each drove a screw propeller.

These had been modified from the original M1875 gun to use a new propellant that burned slower than traditional black powder, producing higher muzzle velocity and improved penetration.

[7] They had a very slow rate of fire, taking ten minutes to reload after every shot, common for guns of the era.

The barbettes for the main battery were composed of 400 mm of compound armor and the supporting tubes that protected the ammunition hoists were the same thickness, but were of steel construction.

[13][16] Between 1896 and 1898, both members of the class were modernized to improve their fighting characteristics as part of a large-scale program in the late 1890s to update some fifteen ironclads that had been completed over the previous decade.

[19][20][21] During exercises in 1895, Formidable accidentally led the fleet into shallow water, running aground herself and causing Amiral Baudin to become stranded as well; a third vessel struck the sea floor but did not become stuck.

[18] As more modern pre-dreadnought battleships began to enter the fleet by the late 1890s, Amiral Baudin and Formidable were transferred from the Mediterranean Fleet—the main French naval force—to the less strategically significant Northern Squadron in 1899.

[23] There, the normal routine of training exercises continued as in earlier years, including joint maneuvers with the Mediterranean Fleet.