was the lead ship of her class of two dreadnought battleships built for the Imperial Japanese Navy (IJN) during the 1910s. Although completed in 1917, she played no role in World War I. Ise supported Japanese forces in the early 1920s during the Siberian Intervention in the Russian Civil War. In 1923, she assisted survivors of the Great Kantō earthquake. The ship was partially modernised in two stages in 1928–1929 and 1931–1932, during which her forward superstructure was rebuilt in the pagoda mast style. Ise was reconstructed in 1934–1937, with improvements to her armour and her propulsion machinery. Afterwards she played a minor role in the Second Sino-Japanese War.
Despite the expensive reconstruction, the ship was considered obsolete by the eve of the Pacific War, and did not see 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, she was rebuilt with a flight deck replacing the rear pair of gun turrets to give her the ability to operate an air group of floatplanes; lack of aircraft and qualified pilots meant that Ise never actually operated aircraft in combat. She participated in the Battle off Cape Engaño in late 1944, where she was one of the ships that decoyed the American carrier fleet supporting the invasion of Leyte away from the landing beaches. Afterwards the ship was transferred to Southeast Asia. In early 1945 Ise participated in Operation Kita, where she transported petrol and other strategic materials to Japan. The ship was then reduced to reserve until American airstrikes in July sank her. After the war Ise was scrapped in 1946–1947.
Design and description
thumb|upright=1.2|left|American ship-recognition drawing of the Ise-class battleships before their conversion
The Ise class was designed as an improved version of the preceding . The ships had a length of overall, a beam of and a draught of at deep load. They displaced at standard load and at deep load, roughly more than the earlier ships. Their crew consisted of 1,360 officers and ratings. their beam to and their draught to . Their displacement increased by 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 carried enough of both to give them a range of at a speed of .
During their 1930s modernisation, the boilers on each ship were replaced by eight new Kampon oil-fired boilers. The ships' secondary armament consisted of twenty Type 3 guns in single mounts. 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. Anti-aircraft defence was provided by four 3rd Year Type 8-centimetre (3 in) anti-aircraft (AA) guns in single mounts. The ships were also fitted with six submerged torpedo tubes, three on each broadside.
In 1931–1933 the AA guns were replaced with eight Type 89 dual-purpose guns, placed beside the forward superstructure in four twin-gun mounts. Two twin-gun mounts for licence-built Vickers two-pounder () light AA guns were also added, while the pair of 14 cm guns on the upper deck were removed.
During the mid-1930s reconstruction, the torpedo tubes were removed and the Vickers two-pounders were replaced by 20 licence-built Hotchkiss Type 96 light AA guns in 10 twin-gun mounts. During the reconstruction the forward pair of 14-centimetre guns in the forecastle were removed 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.
Fire control and sensors
While the details of the ship's fire-control instruments are not fully available, Ise was fitted with a gunnery director after completion. 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 in the early 1930s, one on each side of the forward superstructure. The fire-control systems were again upgraded in the mid-1930s and directors were added for the 2.5 cm AA guns. The ship had a rangefinder installed at the top of the pagoda mast at that time. Type 21 air-search radars were installed aboard the ship in mid-1942. Ise was assigned to the 1st Division of the 1st Fleet in 1917–1918. Captain Kuwashima Shozo relieved Akizawa on 1 December 1918 and he was relieved in his turn by Captain Furukawa Hiroshi on 20 November 1919. On 29 August 1920, the ship began the first of numerous patrols off the Siberian coast and in northern waters in support of Japan's Siberian Intervention against the Bolshevik Red Army. Captain Yokoo Hisashi replaced Furukawa on 20 November and he was replaced by Captain Nagasawa Naotaro in his turn on 1 December 1921. the division, reinforced by the battleships and and the light carrier , sortied from Hashirajima to the Bonin Islands and returned six days later. Ise had a minor refit at the Kure Naval Arsenal in 19–25 February 1942. Together with the rest of the division, she pursued, but did not catch, the American carrier force that had launched the Doolittle Raid on 18 April. On 11 May Ise had an accident which flooded her No. 2 engine room. While under repair, the ship was fitted with one of the first experimental Type 21 early-warning radar sets in the IJN, but it was removed shortly afterwards. Commanded by Vice-Admiral Shirō Takasu, the division was composed of Japan's four oldest battleships, including Ise, accompanied by two light cruisers, 12 destroyers, and two oilers. Official records do not show the division as part of the larger Midway operation, known as Operation AL; they were to accompany the fleet under Admiral Isoroku Yamamoto, but were only to provide support to the Aleutian task force if needed.
Conversion to a hybrid carrier
thumb|upright=1.2|Ise after 1944 reconstruction
The loss of four Japanese aircraft carriers during the Battle of Midway in June severely limited the ability of the IJN to conduct operations and alternatives were sought. Plans for full conversions of battleships into aircraft carriers were rejected on the grounds of expense and, more critically, time, so the IJN settled on removing the rear pair of turrets from the Ise-class ships and replacing them with a flight deck equipped with two rotating catapults. Ise began her conversion on 23 February 1943 and Takeda was relieved by Captain Hase Shinzaburo on 25 April.
During the conversion, all the 14 cm guns were removed and the ship's anti-aircraft suite was heavily reinforced. The eight 12.7 cm Type 89 guns were supplemented with four additional twin mounts and the existing 2.5 cm Type 96 AA twin-gun mounts were replaced by 19 triple-gun mounts for a total of 57 weapons.
These changes increased the ship's overall length to and the removal of the heavy gun turrets and their barbettes reduced her displacement to at deep load, despite the addition of more fuel oil storage. The extra fuel increased Ises range to . The weight reductions decreased her draught to . The crew now numbered 1,463 officers and enlisted men. A pair of Type 13 early-warning radars and an E27 radar detector were installed from 22 to 26 July. From 28 September to 10 October, six racks of 30-tube 12.7 cm anti-aircraft rocket launchers were added.
Battle off Cape Engaño and afterwards
thumb|left|Ise in anti-aircraft combat
thumb|left|Ise fires her main guns during the Battle off Cape Engaño, a phase of the Battle of Leyte Gulf
After the Americans began attacking Japanese installations in the Bonin Islands on 10 October 1944, the aircraft of the Fourth Carrier Division were ordered to prepare for combat by the commander of the Combined Fleet, Admiral Soemu Toyoda. Two days later, the 634th Naval Air Group was reassigned to the Second Air Fleet and began flying to bases in southern Kyushu, among these were nine D4Ys and a dozen E16As assigned to Ise and Hyūga. On 14 October they attacked the aircraft carriers of Task Force 38 near Formosa with little effect and heavy losses. The following day Nakase was promoted to rear admiral.
thumb|Ise (centre left) during the Battle off Cape Engaño
On the morning of 25 October, Ise was positioned astern of the carriers and to protect them with her anti-aircraft guns. Her radar picked up American aircraft at a range of at 07:39. The first attack began at 08:20, with the old battleship engaging enemy aircraft with San Shiki anti-aircraft shells from her main guns with unknown effect. She was not heavily attacked, but two bombs fell nearby. The second wave of aircraft attacked at 10:05 and the ship's gunners claimed to have shot down five of the ten dive bombers. Ise was near missed eight times, although one small bomb struck No. 2 turret. The third wave was detected by her radar at 12:28, but it did not attack the battleship, sinking the damaged Zuikaku and Zuihō instead. Ise rescued 98 survivors from Zuihō before the next attack began around 17:26. She was the primary focus of this wave and was attacked by about 85 dive bombers and at least 11 torpedo bombers. the battleship dodged all the torpedoes, and was struck by only one bomb, near the port catapult. Roughly 34 near misses damaged her hull plating near the waterline and started a small leak that contaminated a small oil tank and caused minor damage to the port boiler rooms. Splinters from the near misses and the single hit killed 5 crewmen and wounded 71.