was the fourth of the six ships completed in the of light cruisers for the Imperial Japanese Navy (IJN), and like other vessels of her class, she was intended for use as the flagship of a destroyer flotilla. She served in the early stages of World War II.
Background and description The second batch of three Nagara-class cruisers, including Yura, was authorized by the Diet as part of the 8-6 Fleet Completion Program on 12 March 1918 although they were not funded until the Fiscal Year 1920 Naval Estimates. The ships were intended to serve as flagships for destroyer and submarine squadrons, long-range scouts for the battlefleet, and to protect Japanese merchant shipping.Lacroix & Wells, pp. 14, 28 The Nagara class was intended to displace at (standard load) and at normal load, but was slightly overweight and actually displaced . They had an overall length of , a beam of , and a draft of Their crew numbered 37 officers and 413 enlisted men. When serving as a flagship, an additional 5 officers and 22 enlisted men were embarked.Lacroix & Wells, pp. 794–796
The Nagaras propulsion system consisted of four geared steam turbines, each driving one propeller shaft using steam from a dozen Kampon water-tube boilers. All of the boilers but two were oil-fired and those used a mixed-firing system where fuel oil was sprayed onto the coal to increase power. The turbines developed a total of and were intended to give the cruisers a speed of . Yura only reached from when the ship ran her sea trials on 18 February 1923. The ships carried enough fuel oil and coal to give them a range of at , an increase of from their designed range.Lacroix & Wells, pp. 23, 795–796Jentschura, Jung & Mickel, p. 107
Armament, fire control and protection
The cruisers' main battery consisted of seven 3rd Year Type guns in single gun mounts protected by gun shields. Five of the guns were mounted on the centerline, one pair mounted back to back forward of the bridge and three aft of the funnels, on the aft superstructure. The remaining guns were positioned abreast the bridge, one on each broadside. For anti-aircraft defense, the ships were fitted with a pair of 3rd Year Type anti-aircraft (AA) guns abreast the middle funnel and two Type 3 heavy machine guns on a platform between the middle and rear funnels, one on each broadside. The ships were equipped with four rotating Type 8 twin-tube mounts for Type 8 torpedoes, two mounts on each broadside. Each tube was provided with a single reload torpedo forward of the mount. The Nagara-class ships were fitted with two rails at the stern that could accommodate 48 No. 1 naval mines These were actually a pair of mines that were connected by a cable and were intended to be dropped ahead of ahead of enemy ships so that hitting the cable would draw one or both mines in towards the ship's hull.Lacroix & Wells, pp. 37–39
The main guns were controlled by a Type 13 director located at the top of the tripod mast. To determine the distance to the target, a pair of rangefinders were fitted, one on the bridge and the other near the 6.5 mm machine guns. An additional rangefinder was positioned on a platform between the forward and middle funnels.Lacroix & Wells, pp. 33, 37
The armor of the 5,500-ton cruisers was designed to protect against American shells and the ships were equipped with a waterline armor belt thick amidships that protected the propulsion machinery. Made from high-tensile steel, it consisted of a inner plate and an outer plate. The belt connected to the armored deck at the top and the double bottom below. The deck armor was also high-tensile steel, thick.
Aircraft Inspired by the British deployment of aviation facilities aboard their C-class and Danae-class cruisers, the Nagara-class cruisers were built with an aircraft hangar in the forward superstructure and a flying-off platform that extended over one of the forward guns. Yura conducted trials with a Yokosuka E1Y2 reconnaissance floatplane in 1927–1928 that was stowed on the flying-off platform and lowered to the sea for takeoff and recovered by a derrick installed next to the bridge. The ship had an experimental spring-powered catapult installed on the platform in mid-1930 for trials with an Aichi E3A1 floatplane. Numerous accidents caused its replacement in October by a cordite-powered, Kure Type 2, Model 2 catapult.Lacroix & Wells, pp. 39-40, 165–166, 746–748
During Yuras September 1933 – January 1934 refit, the hangar was converted into offices for the admiral's staff, radio rooms and storage compartments, the flying-off platform, its catapult and the derrick was removed and a rotating Kure Type 2, Model 3 catapult was installed forward of the mainmast, between two gun mounts. The pole mainmast was converted into a tripod mast with a stronger derrick to handle the aircraft. The cruiser operated a Nakajima E4N2 floatplane until the end of 1934 when a Kawanishi E7K floatplane was embarked.Lacroix & Wells, pp. 171, 175, 193, 195, 747
Modifications During her September 1933 – January 1934 refit, the ship's anti-aircraft suite was upgraded; the 76 mm AA guns was replaced by twin mounts for Type 93 machine guns and the 6.5 mm machine guns were replaced by Lewis guns. In addition a quadruple mount for Type 93 machine guns was installed in front of the bridge and the 2.5-meter rangefinder on the bridge was replaced by a model. After the torpedo boat capsized during a storm in 1934, the IJN realized that many of its ships were top-heavy and began modifying them to make them more stable. Yura began her modifications in October that included reducing the amount of equipment above the upper deck, shortening the foremast, and adding of ballast. The IJN took advantage of the ship's time in the shipyard to convert the mixed-firing boilers to fuel oil only and converting the lower coal bunkers to oil storage and the upper bunkers to a radio room and storage compartments. The ship was also modified to pump of seawater aboard to her improve her stability as necessary.Lacroix & Wells, pp. 167–169, 171, 173
After several of the 5,500-ton cruisers suffered structural damage during the Fourth Fleet Incident in 1935, the ship's hull was strengthened by reinforcing the joints and adding Ducol steel plates to the deck and sides in 1936–1937. A single BI machine gun was installed on the bridge in July 1937. The 13.2 mm machine gun mounts were replaced by four 2.5 cm Type 96 AA guns in twin mounts in 1938.Lacroix & Wells, pp. 168–169, 205, 208
Construction and career
Yura, named after the Yura River,Lacroix & Wells, p. 28 was laid down on 21 May 1921 at the Sasebo Naval Arsenal, launched on 15 February 1922 and completed on 20 March 1923.Whitley, p. 162 The ship became the flagship of the 5th Cruiser Squadron (Sendai) which included her sister ships , , and on 1 April. Together with 2nd Destroyer Squadron, the 5th Squadron patrolled Chinese waters between 25 August and 4 September. The squadron, now consisting of Yura, Nagara and Natori, was assigned to the Second Fleet on 1 December. Reinforced by the light cruiser in May, the division made a cruise to Hahajima Island in October 1924. On 1 December, Yura became a private ship in the 5th Squadron which patrolled Chinese waters off the Yangtze River delta, Qingdao (Tsingtao) and Dalian (Dairen) from 25 March to 23 April 1925. The squadron made another cruise off Qindao beginning on 29 March 1926, but Yura returned to Sasebo on 1 April.Lacroix & Wells, pp. 181–184 She was commanded by Captain Soemu Toyoda from November 1926 to November 1927 and became flagship of Submarine Squadron 1 on 1 December. Two weeks later, the ship began trials with a Yokosuka E1Y2 floatplane and led her squadron on a patrol off Qindao from 26–27 March to 16 April 1927 together with the Third Cruiser Squadron. Yura was reduced to reserve at Sasebo on 1 December 1927.Lacroix & Wells, pp. 184–185
On 10 December 1928,Lacroix & Wells, p. 185 the ship was reactivated with Captain Otagaki Tomisaburō in command and became flagship of the Third Cruiser Squadron of the First Fleet. Escorted by the First Destroyer Squadron, the unit patrolled Chinese waters off Qindao, Dalian, and Qinhuangdao (Chinwangtao) from 29 March to 21 April 1929.Lacroix & Wells, pp. 185–186 Captain Wada Senzō replaced Otagaki on 1 November. The following year, the cruiser squadron visited Dalian in March–April. Yura was fitted with a spring-powered catapult for trials mid-year, but they were unsatisfactory and the catapult was replaced by a cordite-powered one in October 1930. The ship was placed in reserved on 1 December at Sasebo, but she was reactivated on 1 December 1931 and rejoined the Third Cruiser SquadronLacroix & Wells, p. 187 under the command of Captain Umataro Tanimoto.
Following the Manchurian Incident and the subsequent Japanese invasion of Manchuria in 1931, the Imperial Japanese Army (IJA) instigated riots in Shanghai, China, that allowed it to attack units of the Chinese Army in and around Shanghai on 28 January 1932.Jordan, pp. 10–23 The IJN dispatched the Third Cruiser Squadron, consisting of Yura, and her sisters and to the Shanghai area on 28–29 January.Lacroix & Wells, p. 189 On 4 February, the squadron bombarded Chinese fortifications and positions at Wusong, near the confluence of the Huangpu River and the Yangtze River estuary. Yura and the supported attacks by the 9th Division and continued to provide gunfire support until their departure on 20 March. Upon her arrival back in Sasebo, Yura was docked for several months to repair damage inflicted by the muzzle blast of her own guns.
The ship remained part of the Third Cruiser Division until 20 May 1933 when all three sisters were transferred to the newly formed 7th Cruiser Squadron.Lacroix & Wells, p. 191 Captain Rokuzō Sugiyama commanded the ship from 15 June to 15 November 1933.Hackett & Kingsepp The squadron visited ports in Japanese Taiwan on 5–15 July and then patrolled southern Chinese waters until returning to Japan on 21 August, after which it participated in a fleet review off Yokohama four days later. Yura became the flagship of the Second Submarine Squadron on 1 November, although she had begun a lengthy refit in September that lasted until 25 January 1934. The squadron made a brief visit to Qingdao between 27 September and 5 October. After her return, the ship had a refit that improved her stability that lasted until January 1935Lacroix & Wells, pp. 191–192, 196 and Captain Wakabayashi Seisaku assumed command on 1 November. The squadron departed for a cruise off the Kurile Islands on 7 February 1935 and returned on 25 February. It participated in the Great Maneuvers of the Combined Fleet from 20 July to 2 October. Yura was assigned to the Sasebo Guard Squadron, formed from ships in reserve, on 15 November and had her hull strengthened and her engines repaired during a refit from 10 June 1936 to March 1937.Lacroix & Wells, pp. 198, 202, 721