Formidable was an ironclad barbette ship built for the French Navy between her keel laying in late 1879 and her completion in early 1889.

The ships of the class was designed in response to Italian naval expansion, and carried a main battery of three 370 mm (14.6 in) guns all mounted in open barbettes on the centerline.

The armament was chosen after public pressure to compete with the very large guns mounted on the latest Italian ironclads.

After returning to service, she was transferred to the Northern Squadron, based in the English Channel, where the routine of peacetime training maneuvers continued.

Withdrawn from active duty in 1903, she briefly saw service in 1904 but was again removed from use thereafter and was stricken from the naval register in 1909 before being broken up thereafter.

Amiral Baudin and Formidable were designed in the late 1870s as part of a naval construction program that began under the post-Franco-Prussian War fleet plan of 1872.

The Italian vessels carried significantly larger guns than Amiral Duperré, which prompted calls from the Chamber of Deputies to increase the caliber of future ship armament.

[2] The ship was protected with a combination of mild steel and compound armor; her belt was 356 to 559 mm (14 to 22 in) thick and extended for the entire length of the hull.

She took part in the annual fleet maneuvers that year in company with her division-mates and six other ironclads, along with numerous smaller craft.

The exercises began four days later and concluded on 25 July, after which Formidable and the rest of the Mediterranean Fleet returned to Toulon.

[6] During the fleet maneuvers of 1891, which began on 23 June, Formidable remained with the 1st Division, 1st Squadron along with Courbet and the ironclad Dévastation.

[9] She remained in the 1st Squadron in 1895, by which time it had been reduced in size to Amiral Baudin, Formidable, the three Marceaus, Courbet, and Dévastation.

Formidable was pulled free later that night and a subsequent inquiry absolved Gervais of responsibility for the accident.

Formidable and the rest of the Northern Squadron were tasked with conducting a mock attack on Cherbourg two days later.

[21] During the 1902 fleet maneuvers, which began on 7 July, the Northern Squadron attempted to force a passage through the Strait of Gibraltar.