Henri IV was designed by the famous French naval architect Louis-Émile Bertin to evaluate some of his ideas. She was designed to make her a small target and lacked most of the normal rear superstructure common to ships of her period, other than that needed to keep her rear turret from being washed out. Her rear hull had only of freeboard, although she was built up to the normal upper deck height amidships and at the bow for better sea-keeping and to provide for her crew. Her superstructure was narrow and recessed from the hull above the main deck.
General characteristics
Henri IV was smaller than her predecessors, at overall. She had a beam of and a maximum draft of. She was significantly lighter than the Charlemagne-class battleships and displaced only normally, some less than the earlier ships. Her crew consisted of 26 officers and 438 enlisted men.
Propulsion
Henri IV had three vertical triple-expansion steam engines, each driving one propeller shaft. The engines were rated at using steam provided by 24 Niclausse boilers and gave a top speed of. She carried a maximum of of coal that gave her a range of at a speed of.
Armament
Henri IV carried her main armament of two 40-caliber Canon de 274 modèle 1893/1896s in two single-gun turrets, one forward on the upper deck and the other on the main deck at the rear. The guns fired armor-piercing projectiles at a muzzle velocity of. The ship's secondary armament consisted of seven 45-caliber Canon de 138 mm Modèle 1893 naval guns. Four were mounted in individual casemates on the main deck; two more were mounted on the shelter deck with gun shields and the last gun was mounted in a shelter deck turret superfiring over the rear main gun turret. This was the first superfiring turret in naval history and, in this case, was not very successful because the barrel of the 138 mm gun was too short to clear the sighting hood of the turret below. These guns fired shells at muzzle velocities of. Twelve 40-caliber Canon de 47 mm Modèle 1885 Hotchkiss guns were mounted as anti-torpedo boat guns. They were mounted in platforms in the foremast and mainmast and on the superstructure. They fired a projectile at to a maximum range of. Their theoretical maximum rate of fire was fifteen rounds per minute, but only seven rounds per minute sustained. Two submerged torpedo tubes were also carried. Exactly which types of torpedoes carried is unknown, but most of the torpedoes in service during the war had warheads of, maximum speeds of and maximum ranges of.
Armor
Henri IV had a waterline armor belt of Harvey armor that was high and tapered from the maximum thickness of that to at the ship's ends. The belt ended short of the stern in a traverse bulkhead. The lower edge of this belt tapered as well from in thickness. The upper armor belt was mostly thick and ran from the bow to aft of the midsection. It was generally high, but increased to forward and ended in a traverse bulkhead. The maximum thickness of the armored deck was, but tapered to at the ship's ends. Below this was a thinner armored deck that tapered from on the centerline to at the edges. It curved down about to form a torpedo bulkhead before it met up with the inner bottom. This system was based on experiments conducted in 1894 and was more modern than that used in the Russian battleship Tsesarevich although it was still too close to the side of the ship. The main turret armor was in thickness and the ammunition shafts were protected by of armor. The casemates for the 138 mm guns ranged from in thickness and their ammunition tubes had of armor.
Construction and service
Henri IV was laid down at Cherbourg on 15 July 1897 and launched on 23 August 1899, but did not enter service until September 1903, at a cost of ₣15,660,000 francs. The ship spent the early part of World War I as the guardship at Bizerte, until February 1915 when she was assigned to the newly formed Syrian Squadron. This squadron was intended to attack Turkish positions and lines of communication in Syria, Lebanon, Palestine and the Sinai Peninsula. Henri IV was transferred to the French squadron in the Dardanelles campaign to replace the sunk battleship and the damaged after the Allies suffered heavily during their first attempt to sail through the Dardanelles and past the fortifications them on 18 March 1915. The ship bombarded Kum Kale, on the Asiatic side of the Dardanelles in support of the French diversionary landing on 25 April 1915, and provided fire support for the troops ashore for the rest of the month. She was hit eight times while providing support during this time. Three of her 138.6 mm guns had been dismounted by November 1914 and sent to reinforce the French naval mission to Serbia, known as "Mission D", by rail from Salonica. In 1916, she was assigned to the Complementary Division of the 3rd Battle Squadron. Subsequently she served with the French Eastern Division in Egypt and then she was sent to Taranto in 1918 as a depot ship. Henri IV was stricken from the Navy List in 1920 and scrapped the following year.
