The s were designed as improved versions of the armored corvette suitable for foreign deployments. Unlike their predecessor the Alma-class ships were true central battery ironclads as they were fitted with armored transverse bulkheads. Like most ironclads of her era she was equipped with a metal-reinforced ram. Alma measured between perpendiculars, with a beam of. She had a mean draft of and displaced.
Propulsion
The ship had a single Mazeline horizontal return connecting-rod steam engine driving a single propeller. Her engine was powered by four oval boilers. On sea trials the engine produced and the ship reached. Alma carried of coal which allowed the ship to steam for at a speed of. She was barque-rigged and had a sail area of.
Armament
Alma mounted her four Modèle 1864 breech-loading guns in the central battery on the battery deck. The other two 194 mm guns were mounted in barbettes on the upper deck, sponsoned out over the sides of the ship. The four guns were also mounted on the upper deck. She later exchanged her 194 mm guns for newer Modèle 1870 guns. The armor-piercing shell of the 20-caliber Mle 1870 gun weighed while the gun itself weighed. The gun fired its shell at a muzzle velocity of and was credited with the ability to penetrate a nominal of wrought iron armour at the muzzle. The guns could fire both solid shot and explosive shells.
Armor
Alma had a complete wrought iron waterline belt, approximately high. The sides of the battery itself were armored with of wrought iron and the ends of the battery were closed by bulkheads of the same thickness. The barbette armor was thick, backed by of wood. The unarmored portions of her sides were protected by iron plates.
Service
Alma was laid down at Lorient on 1 October 1865 and launched on 26 November 1867. The ship began her sea trials on 24 August 1869, but did not enter service until the following year, after sailing to Brest to have sheathing added to protect her armor. She was commissioned as the flagship of the China Squadron under command of Rear Admiral Dupré and the ship departed Brest on 15 June 1870. She grounded on a shoal in the Inland Sea on 15 July and lost her false keel. After the start of the Franco-Prussian WarAlma blockaded the Prussian corvettes and in the Japanese port of Yokohama from mid-December 1870 until the end of the war. On 24 August 1871 Alma rode out a typhoon in Yokohama. She was relieved by Belliqueuse on 1 August 1872 and reached Toulon on 16 January 1873. The ship was assigned to the Evolutionary Squadron on 8 October 1873. She was in reserve in Cherbourg from 1876 to 1881. Alma recommissioned on 1 March 1881 and was assigned to the Levant Squadron. From 6–16 July 1881 the ship bombarded the Tunisian port of Sfax as part of the French occupation of Tunisia. She was reduced to reserve in Cherbourg on 8 January 1883. The ship was condemned on 12 March 1886, but Alma was not sold until May 1893 for 129,000 francs.
