Alma-class ironclad

The Alma-class ironclads were designed by Henri Dupuy de Lôme as improved versions of the armored corvette suitable for foreign deployments. The original plan for these ships was to have a two-deck battery with four guns on the battery deck and four guns mounted above them on the upper deck, one gun at each corner of the battery. This design was changed to substitute four barbettes for the upper battery, but the addition of armored bulkheads proved to be very heavy and the rear pair of barbettes had to be deleted to save weight. In partial compensation the 164-millimeter guns in the remaining forward barbettes were replaced by an additional pair of 194-millimeter guns. The ships were built from the same general plan, but differed amongst themselves. They measured between perpendiculars, with a beam of . The ships had a mean draft of and displaced . 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 The Alma-class ships 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 their sides were protected by iron plates. ==Ships==

During the Franco-Prussian War of 1870–71 Thétis, ''Jeanne d'Arc and Armide were assigned to the Northern Squadron that attempted to blockade Prussian ports on the Baltic until ordered to return to Cherbourg on 16 September 1870. Montcalm, Atalante, and Reine Blanche cruised the North Sea and Montcalm later captured the Prussian Barque Union and watched a Prussian corvette in Portuguese waters. Alma was en route to the Far East when the war began and she blockaded a pair of Prussian corvettes in Yokohama harbor once she arrived at Japan. In 1875, the latter ship rammed and sank the dispatch vessel Forfait. On 3 July 1877 Atalante'' participated in the Battle of Thuận An in August 1883. This was an attack by the French on the forts defending the mouth of the Perfume River, leading to the Vietnamese capital of Huế in an attempt to intimidate the Vietnamese government. During the Sino-French War of 1884–85 the ship was in Huế in early September 1884, but she carried Admiral Amédée Courbet to Keelung, Taiwan on 23 September. ==Notes==