Iéna was a pre-dreadnought battleship built for the French Navy (). Completed in 1902 and named for one of Napoleon's victories, the ship was assigned to the Mediterranean Squadron and remained there for the duration of her career, frequently serving as a flagship. She participated in the annual fleet manoeuvres and made many visits to French ports in the Mediterranean. In 1907, while Iéna was docked for a refit, there was a magazine explosion that was probably caused by the decomposition of old Poudre B propellant. It killed 120 people and badly damaged the ship. Investigations were launched afterwards, and the ensuing scandal forced the Navy Minister to resign. While the damage could have been repaired, the five-year-old ship was considered obsolete and worth neither the time nor the expense; her salvaged hulk was used as a gunnery target in 1909, then sold for scrap in 1912.
Design and description
On 11 February 1897 Navy Minister () Armand Besnard, after consultations with the Supreme Naval Council (), requested a design for an enlarged with a maximum displacement of , an armour scheme capable of preserving stability and buoyancy after several penetrations of the hull and the resulting flooding, an armament equal to those of foreign battleships, a speed of and a minimum range of . The Director of Naval Construction (), Jules Thibaudier, had already prepared a preliminary design two months earlier with improved Harvey armour, but it was modified to increase the height of the belt armour above the waterline and to replace the guns of the Charlemagnes with guns. Thibaudier submitted his revised design on 9 February and it was approved by the Board of Construction () on 4 March with minor revisions.
Iéna had an overall length of , a beam of and, at deep load, a draught of forward and aft. She displaced at normal and at deep load. As a flagship, Iéna had a crew of 48 officers and 731 ratings; as a private ship, her crew numbered 33 officers and 668 ratings. The ship was fitted with large bilge keels, but, according to naval historian N.J.M. Campbell, was reported to roll considerably and pitch heavily, although this is contradicted by Captain () Bouxin's report of November 1905: "From the sea-keeping point of view the Iéna is an excellent ship. Pitching and rolling movements are gentle and the ship rides the waves well." Naval historians John Jordan and Philippe Caresse believe the ship was a good gun platform because she had a long, slow roll and she manoeuvred well.
Iéna was powered by a trio of four-cylinder vertical triple-expansion steam engines, each driving a three-bladed propeller that was in diameter on the outer shafts and on the centre shaft. The engines were powered by 20 Belleville boilers at a working pressure of and were rated at a total of to give the ship a speed of . During her sea trials on 16 July 1901, the ship barely exceeded her designed speed, reaching from . Iéna carried a maximum of of coal; this allowed her to steam for at a speed of . The ship's 80-volt electrical power was provided by four dynamos, a pair each of 600- and 1,200-ampere capacity.
Armament and armour
Like the Charlemagne-class ships, Iéna carried her main armament of four 40-calibre Canon de Modèle 1893–1896 guns in two twin-gun turrets, one each fore and aft of the superstructure. Each turret had a dedicated 300-ampere dynamo to traverse it and to power the ammunition hoist. The guns, however, were manually elevated between their limits of −5° and +15°, and they were normally loaded at an angle of −5°. The guns fired armour-piercing, capped (APC) projectiles at the rate of one round per minute at a muzzle velocity of . This gave a range of at the maximum elevation of +15°. The magazines stored 45 shells per gun, and an additional 14 projectiles were stowed in each turret.
The ship's secondary armament consisted of eight 45-calibre Canon de 164.7 mm Modèle 1893 guns, which were mounted in the central battery on the upper deck, and fired APC shells. At their maximum elevation of +15°, their muzzle velocity of gave them a maximum range of . Each gun was provided with 200 rounds, enough for 80 minutes at their sustained rate of fire of 2–3 rounds per minute. She also carried eight 45-calibre Canon de Modèle 1893 guns in single, unprotected, mounts on the shelter deck. These guns fired a projectile at , which could be trained up to 20° for a maximum range of . Their theoretical maximum rate of fire was six rounds per minute, but only three rounds per minute could be sustained. Each gun was provided with 240 shells in the ship's magazine.