Линкоры типа «Исэ»: История и Модернизации

Class of dreadnought battleship

The Ise class battleships (伊勢型戦艦) were a pair of dreadnought battleships built for the Imperial Japanese Navy (IJN) during World War I. Both ships carried supplies for the survivors of the Great Kantō earthquake in 1923. They were modernized in 1934–1937 with improvements to their armour and machinery and a rebuilt superstructure in the pagoda mast style. Afterwards they played a minor role in the Second Sino Japanese War. Despite the expensive reconstructions, both vessels were considered obsolete by the eve of the Pacific War, and neither saw significant action in the early years of the war. Following the loss of most of the IJN's large aircraft carriers during the Battle of Midway in mid 1942, they were rebuilt with a flight deck replacing the rear pair of gun turrets to give them the ability to operate an air group of floatplanes. A lack of aircraft and qualified pilots, however, meant that they never actually operated their aircraft in combat. While awaiting their air group, the sister ships were occasionally used to ferry troops and material to Japanese bases. They participated in the Battle off Cape Engaño in late 1944, where they decoyed the American carrier fleet supporting the invasion of Leyte away from the landing beaches. Afterwards both ships were transferred to Southeast Asia; in early 1945 they participated in Operation Kita, where they transported petrol and other strategic materials to Japan. The sisters were then reduced to reserve until they were sunk during American airstrikes in July. After the war they were scrapped in 1946–1947.

The design of the Ise class battleships was shaped both by the ongoing international naval arms race and a desire among Japanese naval planners to maintain a fleet of capital ships powerful enough to defeat the United States Navy in an encounter in Japanese territorial waters. The IJN's fleet of battleships had proven highly successful in 1905, the last year of the Russo Japanese War, which culminated in the destruction of the Russian Second and Third Pacific Squadrons at the Battle of Tsushima. In the aftermath, the Japanese Empire immediately turned its focus to the two remaining rivals for imperial dominance in the Pacific Ocean: Britain and the United States. This ratio, Satō theorized, would enable the Imperial Japanese Navy to defeat the US Navy in one major battle in Japanese waters in any eventual conflict. This was the genesis of the Eight Eight Fleet Program, the development of a cohesive battle line of sixteen capital ships. The launch of in 1906 by the Royal Navy raised the stakes, and complicated Japan's plans. Displacing and armed with ten guns, Dreadnought rendered all existing battleships obsolete by comparison. The launch of the battlecruiser the following year was a further setback for Japan's quest for parity. When the two new s and two armoured cruisers, launched by 1911, were outclassed by their British counterparts, the Eight Eight Fleet Program was restarted. The first battleships built for the renewed Eight Eight Fleet Program were the two dreadnoughts of the , ordered in 1907 and laid down in 1908. In 1910, the Navy put forward a request to the Diet (parliament) to secure funding for the entirety of the program at once. Because of economic constraints, only four battlecruisers and a single battleship of the Fusō class were ultimately approved by the Diet. Three more Fusō class ships (Japanese battleship Yamashiro, Japanese battleship Ise, and Japanese battleship Hyūga) were approved and all three were ordered in April 1913. While Yamashiro was laid down later that year, the IJN lacked the funding to proceed with the construction of Ise and Hyūga until the Diet authorized additional funding for the ships in July 1914.

The progress of Fusōs construction, while the IJN waited for the funding to be released and foreign developments, caused the IJN to reassess the Fusō class design. The distribution of the midships gun turrets was the most obvious flaw as they complicated the protection of the midships magazine and exposed more of the ship to the blast effects of the guns when they fired. Another issue was that Japanese sailors had problems maintaining a high rate of fire with the shells used in the manually loaded secondary guns used in the Fusō class and earlier designs. To resolve this issue, the IJN designed a smaller gun that offset its lighter shell weight with a higher rate of fire. It also decided that the barbette armour of the earlier ships was too thin and wanted a modest increase in speed to partially counter the higher speeds of the latest foreign ships like the British s and Russian s. For financial reasons more powerful engines could not be ordered so the new design was lengthened slightly and the boiler rooms enlarged to increase speed by to To save weight the forecastle deck was shortened so that the lower midships gun turret was lower than in the Fusō class. This reduced the crew's accommodations despite a significant increase in the crew's numbers and naval historian Fukui Shizuo believed that these ships had the worst habitability of any Japanese capital ship. The final design was designated A 92 by the IJN. The ships had a length of overall, a beam of and a draught of at deep load. They displaced at normal load and at deep load, roughly more than the preceding class. Their crew consisted of 1,360 officers and enlisted men. They had a metacentric height of at deep load. During the ships' modernization during the 1930s, their forward superstructures were enlarged with multiple platforms added to their tripod foremasts. Both ships were also given torpedo bulges to improve their underwater protection and to compensate for the weight of the additional armour. In addition, their sterns were lengthened by These changes increased their overall length to , their beam to and their draft to Their displacement increased over to at deep load. The crew now numbered 1,376 officers and enlisted men. Each of the boilers consumed a mixture of coal and oil and the ships had a stowage capacity of of coal and of fuel oil, which gave them a range of at a speed of Ise and Hyūga had three generators of capacity and two turbo generators at 225 volts. During their 1930s modernization, the boilers on each ship were replaced by eight new Kampon oil fired boilers, fitted into the former aft boiler room, and the forward funnel was removed. except for No. 6 turret as its supporting structure could not be lowered. The recoil mechanism of the guns was also changed from a hydraulic to a pneumatic system, which allowed for a faster firing cycle of the main guns. By World War II, the guns used Type 91 armour piercing, capped shells. Each of these shells weighed and was fired at a muzzle velocity of They had a maximum range of at +20 degrees of elevation and at +43 degrees after modernization. Also available was a high explosive shell that had a muzzle velocity of A special Type 3 Sanshikidan incendiary shrapnel shell was developed in the 1930s for anti aircraft use. The ships' secondary armament consisted of twenty 50 calibre Type 3 guns. Eighteen of these were mounted in casemates in the forecastle and superstructure and the remaining pair were mounted on the deck above them and protected by gun shields. They had a maximum elevation of +20 degrees which gave them a range of Each gun had a rate of fire of up to 10 rounds per minute. Anti aircraft defence was provided by four 40 calibre 3rd Year Type 8 centimetre#tag:ref|These guns were license built British quick firing (QF) QF 12 pounder guns. While the Japanese designated them as 8 cm, their actual calibre was 76.2 mm. The ships were also fitted with six submerged torpedo tubes, three on each broadside. They carried twelve to eighteen 6th Year Type torpedoes which had a warhead. They had three settings for range and speed: at , at , or at
In 1931–1933 the AA guns were replaced with eight 40 calibre Type 89 dual purpose guns, fitted on both sides of the forward superstructures in four twin gun mounts. When firing at surface targets, the guns had a range of ; they had a ceiling of at their maximum elevation of +90 degrees. Their maximum rate of fire was 14 rounds a minute, but their sustained rate of fire was around eight rounds per minute. Two twin gun mounts for license built Vickers two pounder light AA guns were also added. These guns had a maximum elevation of +80 degrees and a rate of fire of 200 rounds per minute. The pair of 14 cm guns on the upper deck were removed at this time. These guns had an effective range of , and an effective ceiling of at an elevation of 85 degrees. The maximum effective rate of fire was only between 110 and 120 rounds per minute because of the frequent need to change the fifteen round magazines. In addition the forward pair of 14 cm guns in the forecastle were removed at this time and the maximum elevation of the remaining guns was increased to +30 degrees. The turrets were protected with an armour thickness of on the face and 76 mm on the roof. The casemate armour was thick and that of the barbettes was 299 mm thick rather than the originally planned 305 mm. The sides of the conning tower were 305 mm thick. The Ise class were the only Japanese battleships to place the powder magazine above the shell magazine as the IJN wished to put as much space as possible between the highly flammable propellant and mine and torpedo detonations. The danger from plunging shells at long distances was not appreciated until the fatal magazine explosions of three British battlecruisers during the 1916 Battle of Jutland graphically demonstrated the point. To further protect the magazines the depth of the double bottom was increased to a total of underneath the barbettes and magazines. Additionally, the vessels contained 660 watertight compartments to preserve buoyancy in the event of battle damage. In addition to the torpedo bulge added when the ships were modernized, the deck armour over the machinery and magazines was increased to a total thickness of 140 mm. Inside the original skin of the ships, two torpedo bulkheads were also added and the turret roofs were increased to a total of of armour.

While the details of the ships' fire control instruments are not fully available, it is known that the ships were fitted with a fire control director after completion. No computer was fitted at that time and data from the rangefinders had to be processed manually. Turrets 2, 3, and 5 were built with imported Bausch & Lomb rangefinders. These were felt to be inferior to the British Barr & Stroud instruments used on other ships and were removed in 1920. They were replaced by either the British rangefinders or domestically built instruments of length. In the late 1920s the fire control systems were upgraded and additional platforms were added to the foremast to accommodate them. A pair of directors for the 12.7 cm AA guns were added, one on each side of the forward superstructure, in the early 1930s. The fire control systems were again upgraded in the mid 1930s and directors were added for the 25 mm AA guns. Both ships had rangefinders installed at the top of the pagoda mast at that time. Type 21 air search radars were installed aboard the sisters in mid 1942. A catapult and a collapsible crane were fitted on the stern during the mid 1930s modernization, and the ships were equipped to operate three floatplanes, although no hangar was provided. The initial Nakajima E4N2 biplanes were replaced by Nakajima E8N2 biplanes in 1938.

The rear turrets, the barbettes and their supporting structures were removed beginning in early 1943 and the openings in the middle deck were covered by 152 mm plates salvaged from the turret armour. All of the 14 cm guns were removed and the casemate openings sealed off. Four additional twin 12.7 cm mounts were added, one pair abreast the funnel and the other abreast the conning tower. The original ten twin 25 mm gun mounts were replaced by triple mounts and nine new triple mounts were added, a total of 57 guns. Two each Type 94 and Type 95 AA directors were added to control the additional guns. The ammunition for these new guns was stored in the magazines originally used for the 14 cm guns and for Turret No. 5. During 1944, the ships' AA defences were reinforced with an additional dozen triple and eleven single 25 mm gun mounts, for a total of 104 barrels, and a pair of Type 13 early warning radars were added. In September six 30 round AA rocket launchers were added on the sides of the flight deck. The hangar was wide forward and at the rear. It was high and designed to stow nine aircraft. It was fitted with fire fighting foam and carbon dioxide dispensers as a result of wartime experience. The T shaped lift was wide at its forward end and wide at its aft end. It was also 12.1 metres long and had a capacity of Petrol storage tanks with a capacity of were installed in the former magazine of Turret No. 6 to provide each aircraft with enough fuel for three sorties. To recover the aircraft the collapsible crane formerly on the stern was moved up to the port side of the flight deck. Another crane was intended on the starboard side, but it was never fitted. The ships had an air group of 11 each of Yokosuka D4Y dive bombers (Allied reporting name "Judy") and Aichi E16A reconnaissance aircraft (Allied reporting name "Paul"). Both aircraft had development problems and neither air group ever had all of its intended aircraft. Coupled with a shortage of trained pilots, neither ship ever used its aircraft during combat.

After the loss of the fast battleship Japanese battleship Hiei at the Naval Battle of Guadalcanal in late 1942 to rudder damage, the IJN decided to reinforce the protection of the steering compartment and to create an auxiliary steering compartment. The protection of the former was strengthened by the addition of a concrete wall at least in thickness and some of the armour removed from the turrets was used to protect the latter. The double bottom below the former positions of aft turrets was converted to hold fuel oil; this increased the ships' endurance to at a speed of 16 knots.

Upon commissioning, the sister ships were assigned to the 1st Battleship Division of the 1st Fleet. Hyūga had an explosion in one of her main gun turrets that killed 11 men and injured 25 in 1919; the following year she accidentally collided with and sank a schooner, losing two crewmen. Before the start of the Pacific War, both ships frequently exercised off the coasts of the Soviet Union, Korea and China in addition to training in Japanese waters. Ise hosted Edward, Prince of Wales, and his aide de camp Lieutenant Louis Mountbatten in 1922 during the prince's visit to Japan. In Korea Bay when the 1923 Great Kantō earthquake struck, they sailed to Kyushu where they loaded supplies for the victims on 4 September. Together with two other battleships and a pair of light cruisers, Ise sank the destroyer Japanese destroyer Yayoi in 1926 during gunnery practice. Ises AA armament was upgraded in 1931 and Hyūgas two years later. The latter ship was modernized in 1934–36 and Ise in 1935–37, both at Kure Naval Arsenal. During the Second Sino Japanese War, the sisters frequently patrolled the Chinese coast in support of the blockade imposed by Japan. In August 1937 Hyūga ferried two battalions of Special Naval Landing Forces to Port Arthur. Three years later, she served as the flagship for the Emperor of the puppet state of Manchukuo, Henry Pu yi, during his state visit to Japan in June 1940. On 15 November the ships were transferred to the 2nd Battleship Division of the 1st Fleet. The sisters were refitted in late 1940 in preparation for war, which included the fitting of external degaussing coils and additional AA directors. the sisters sortied for the Bonin Islands with four other battleships and the light carrier Japanese aircraft carrier Hōshō as distant cover for the fleet attacking Pearl Harbor, and returned six days later. During gunnery training on 5 May, there was a premature detonation in the left gun of Hyūgas Turret No. 5 that disabled both guns and killed 51 crewmen. Both aft magazines were flooded to douse the resulting fire and save the ship. She received temporary repairs during which the turret was removed and replaced by a circular armour plate on which three triple 25 mm gun mounts were positioned. On 11 May a valve in Ises No. 2 engine room stuck in the open position and flooded the engine room. While under repair at Kure, both ships received prototype Type 21 radars. They returned home on 14 June and the IJN began preliminary planning to replace the lost carriers with hybrid carriers converted from battleships. The sisters were selected for conversion and detached from the division on 14 July in preparation. They remained on "standby alert" until the actual conversions began. After completing her sea trials, Ise was attached to the Imperial Japanese Naval Academy at Etajima and ferried troops and munitions to the naval base at Truk in October. In November the ship began working up, joined by the newly completed Hyūga the following month, and both rejoined the 2nd Battleship Division. On 1 May 1944, the sisters were transferred to Rear Admiral Matsuda Chiaki's reformed Fourth Carrier Division of the 3rd Fleet.

In October 1944, the two ships were involved in the Battle off Cape Engaño. Shortages of aircraft and serviceability problems greatly retarded pilot training and the ships only had a total of 17 D4Ys and 18 E16As on hand on 1 October; of these, only 6 and 16 were operational, respectively. The Japanese plan for the defence of the Philippines envisioned that the surviving carriers would be used to lure the American carrier forces away from the invasion area to a position where the carriers could be attacked by land based aircraft, while the transports would be attacked by the rest of the IJN. The other carrier air groups were not in much better shape and the Japanese decided to retain the aircraft ashore for use against the American carriers. The Fourth Carrier Division, including the sisters, fleet carrier Japanese aircraft carrier Zuikaku and the light carriers Japanese aircraft carrier Zuihō, Japanese aircraft carrier Chitose, and Japanese aircraft carrier Chiyoda, was assigned to the Northern Force under the command of Vice Admiral Jisaburō Ozawa. The Ise class sisters sailed from Yashima on 20 October. Ozawa's carrier group was a decoy force, divested of all but 108 aircraft, intended to lure the American fleet away from protecting the transports at the landing beaches. On the morning of 24 October, the group was facing a United States Navy force that included ten carriers containing 600–1,000 aircraft. Ozawa launched the bulk of his few aircraft to attack the American carriers as a distraction. They inflicted no damage and caused the Americans to search in the direction from which they had attacked. The Americans finally spotted the Japanese carriers at 16:40, some 200 mile (322 km) east of Cape Engaño, the northeastern tip of Luzon. The American carriers were spread out and it was very late in the day to launch an airstrike, so Admiral William Halsey, commander of the Third Fleet decided to mass his carriers in a position to attack the following morning. Ozawa reversed course during the night, correctly believing that the Americans would follow him north. Although they had lost contact during the night, the Americans did find the Japanese carriers at 07:35. They had already launched an airstrike of 180 aircraft that was orbiting 50 mile (80 km) ahead of the American carriers while waiting for the Japanese ships to be located. This was just the first of a total of five airstrikes that the Americans launched that day. The sisters were not heavily engaged by the early airstrikes, which instead focused on Ozawa's fleet and light carriers, sinking carriers Zuikaku, Chitose and Zuihō, and the destroyer Japanese destroyer Akizuki, while the carrier Chiyoda and the cruiser Japanese cruiser Tama were crippled. Ise claimed to have shot down five attacking dive bombers from the second wave and one small bomb detonated on Turret No. 2. Hyūga was lightly damaged by near misses that ruptured some hull plating in her bulge and peppered her superstructure with splinters. She took on a 5 degree list that was quickly corrected before she was ordered to tow Chiyoda to safety. Her attempt was unsuccessful and Chiyoda had to be abandoned,

Ise was attacked by 80 odd aircraft from the fourth wave, but they failed to inflict any serious damage. She dodged 11 torpedoes and was only hit by a bomb once, on the bulge outboard of the port catapult. Some 34 other bombs near missed her, spraying her with splinters and ruptured some hull plates that contaminated some fuel oil and caused leaks in her port boiler rooms. While an exact total of her casualties is not available, it has been estimated that 5 men were killed and some 111–121 crewmen were wounded during this attack. before the Japanese reached Kure on 20 February. The Fourth Carrier Division was disbanded on 1 March and the sisters were reduced to 1st rank reserve ships. On 19 March Kure was attacked by aircraft from Task Force 58 and Hyūga was hit three times by bombs that killed 37 men and wounded 52. Her gunners claimed to have shot down one American dive bomber during the attack. Ise was hit twice during the attack, but her casualties, if any, are unknown. The ships were turned into floating AA batteries over the next several months although it availed them little when they were attacked again by American carrier aircraft in July. On the 24th Ise was struck by five bombs and near missed multiple times; all told she lost 50 crewmen killed and many others wounded. The bombs started numerous leaks and Ise began to settle by the bow, although she was returned to an even keel after three days pumping. Hyūga was a primary focus of the attack and she received 10 direct hits and up to 30 near misses. She was badly damaged with some 200 odd crewmen killed and 600 wounded during the attack. She slowly foundered over the next two days and was not attacked when the Americans returned four days later. This time it was Ises turn and she was struck 11 or more times with many near misses that put her on the bottom in shallow water with a 15 degree list. The sisters were struck off the Navy List in November and their wrecks were scrapped after the war.