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.

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.

On 11 February 1897 Navy Minister (Ministre de la Marine) Armand Besnard, after consultations with the Supreme Naval Council (Conseil supérieur de la Marine), requested a design for an enlarged Charlemagne-class battleship with a maximum displacement of 12,000 tonnes (11,810 long tons), 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 18 knots (33 km/h; 21 mph) and a minimum range of 4,500 nautical miles (8,300 km; 5,200 mi).

"[6] 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.

The engines were powered by 20 Belleville boilers at a working pressure of 18 kg/cm2 (1,765 kPa; 256 psi) and were rated at a total of 16,500 metric horsepower (12,100 kW) to give the ship a speed of 18 knots (33 km/h; 21 mph).

[3] During her sea trials on 16 July 1901, the ship barely exceeded her designed speed, reaching 18.1 knots (33.5 km/h; 20.8 mph) from 16,590 metric horsepower (12,200 kW).

Iéna carried a maximum of 1,165 tonnes (1,147 long tons) of coal; this allowed her to steam for 4,400 nautical miles (8,100 km; 5,100 mi) at a speed of 10.3 knots (19.1 km/h; 11.9 mph).

[8] Like the Charlemagne-class ships, Iéna carried her main armament of four 40-calibre Canon de 305 mm (12 in) Modèle 1893–1896 guns in two twin-gun turrets, one each fore and aft of the superstructure.

[9] 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,[3] and fired 54.2-kilogram (119 lb) APC shells.

[13] Iéna's anti-torpedo boat defences consisted of twenty 40-calibre Canon de 47 mm (1.9 in) Modèle 1885 Hotchkiss guns, fitted in platforms on both military masts, embrasures in the hull, and in the superstructure.

[14] Rear-Admiral (Contre-amiral) René Marquis criticised the arrangements for the 47 mm guns in a 1903 report: "The number of ready-use rounds is insufficient and the hoists are desperately slow.

The lower strake was backed by a highly subdivided cofferdam intended to reduce flooding from any penetrating hits as its compartments were filled by 14,858 water-resistant "bricks" of dried and compressed Zostera seaweed (briquettes de zostère).

[18] Ordered on 3 April 1897,[19] and named after the French victory at the Battle of Jena,[20] Iéna was laid down at the Arsenal de Brest on 15 January 1898.

After the completion of the repairs the ship began a series of port visits in France and French North Africa which would be repeated for most of her career.

[22] Iéna participated in the fleet review off Naples in April–May 1904 when Émile Loubet, President of France, had a state visit with King Victor Emmanuel III of Italy.

In 1905 the ship was refitted during 15–25 April and then participated in the summer cruise of the Mediterranean Squadron, during which she visited ports in France and French North Africa between 10 May and 24 June.

After the conclusion of the exercise on 4 August, she spent most of the next several months refitting, aside from participating in an international naval review in Marseilles on 16 September with British, Spanish and Italian ships.

The Senate appointed its commission on 20 March under the chairmanship of Ernest Monis; the Chamber of Deputies followed eight days later with Henri Michel as chair.

Fallières appointed a technical commission on 6 August that included mathematician Henri Poincaré, chemist Albin Haller and the inventor of Poudre B, Paul Vieille, that failed to come to a definite conclusion.

[28] The reason for the explosion became a cause célèbre with accusations of gross negligence by the government such that Thomson was forced to resign on the last day of the debate.

[29] The multiple explosions ripped open the ship's side between Frames 74 and 84 down to the lower edge of the armour belt, and all the machinery in this area was destroyed.

After it was estimated that it would take seven million francs and two years to fully repair Iéna, which was already obsolete, the navy decided to decommission her and use her as a target ship.