Battlecruiser – fast battleship Haruna

Contemporary 8 cm anti-aircraft guns had a limited range and ceiling. With dynamic development of naval aviation, in the late 1920s, they had to be replaced by more modern 12 cm calibre types. The decision to choose that calibre was forced by a trend that prevailed in the development of anti-aircraft artillery. The 8 cm gun was also marked by poor workmanship and unsatisfactory ballistic characteristics. While developing the new type of gun, engineers concentrated on replacing the breech, increasing shell weight and improving ballistic parameters. A prototype, presented by engineer Hata was tested and received positive assessment of Japanese specialists. It was introduced to the Japanese Navy under designation 45 Kōkei 10 Nen Shiki 12 cm Kōkaku hō. Its service was not long as significance of naval aviation and role of aircraft carriers increased. It forced the Imperial Navy to search for the most effective solutions for anti-aircraft protection. Th IJN followed the path paved by the navies of other countries and slightly increased the calibre of anti-aircraft guns. On the basis of the 12 cm gun in service, a new design of a 12.7 cm anti-aircraft gun was developed at the end of 1928. After three years of construction work, the navy arsenals in Kure and Hirosima built the first piece. Trials of the experimental gun began in 1931 and after their completion, the gun was approved on February 6, 1932 as type 89 Shiki, 12.7 cm calibre with 40 calibres length (40 Kōkei 89 Shiki 12.7 cm Kōkaku hō). The new gun was to form an aerial target acquisition system along with the type 91 targeting system that was simultaneously undergoing trials. The gunnery tests gave positive results and soon the new gun became standard armament of Japanese ships. The 12.7 cm gun was designed by engineer Chiyokichi Hada. It was produced in the arsenal in Kure with cooperation of the armament factory in Hiroshima. Turrets for the gun were manufactured by arsenals in Kure and Yokosuka.

Light anti-aircraft artillery

The 40 mm6 gun was bought in the Vickers factory (Mk VIII) in 1925 and underwent intensive testing in the Kure Naval Arsenal. After achieving positive results, the gun was approved and introduced into the navy weaponry. Its Japanese counterpart was constructed by Admiral F. Shimizu and manufactured in factories in Kure and Yokosuka under supervision of Shimizu himself. The gun was mounted on all battlecruisers and battleships. Detailed specifications and number of guns mounted on ships are presented in Table 15. During its service, the gun turned out to be difficult to operate as it demanded highly skilled personnel. That was why the navy began searching for different anti-aircraft types of gun to replace it. In the middle of 1935, a decision was made to rearm the ships with smaller calibre guns.
All heavy units of the Imperial Navy – fast battleships and battleships – were armed with standard 25 mm anti-aircraft artillery. Made by Hotchkiss, the gun was purchased in 1930 from France with designation 94 and 95 Shiki 25 mm Kijun. Until June 19, 1935, the gun was tested in Yokosuka. Decision to introduce a smaller calibre gun was caused by difficulties in operating 40 mm guns. Upon trials completion, the gun’s final version, slightly modified with help of specialists form the German Rheinmetall company, was designated 96 Shiki 25 mm Kiju 1 kata (Kiju – machine gun). A twin-barrel version was adopted on August 6, 1936, and introduced into production as 96 Shiki 25 mm Kiju 2 kata. Three-barrel mounts were approved in 1941 and single-barrel ones in 1943.
In the first period of the battleships service, only electrically powered, twin-barrel type 96 mark 2 gun turrets, designed by Rear Admiral K. Katsuta were used. The guns were produced in Toyokawa and Yokosuka under the supervision of Rear Admiral M. Hori. Target acquisition was provided by type 95 anti-aircraft gun directors. Ammunition included high explosive, tracer, incendiary and armour-piercing rounds. It was common to add a tracer to every four or five rounds for better trajectory observation. Eight feeders supplied rounds to ready-service ammunition boxes. There were 2,600 anti-aircraft rounds per gun and the immediate reserve, ready to be used, comprised 100 rounds. The air-cooled gun was fed from the top by 15-round magazines that provided theoretical rate of fire of 220 rounds per minute.
The twin-barrel mount was electrically powered, in three planes, by a system of two 1 hp motors. They allowed the gun to make full turn at a rate of 18 degrees per second, the elevation rate was 12 degrees per second. The gun could be manually operated by a crew of 7.

Machine guns

Similarly to the 25 mm anti-aircraft gun, machine guns intended for mounting on Japanese ships, were bought in France. The most favoured was the 13.2 mm Hotchkiss machine gun that was to replace the 12.7 mm Vickers. The purchased guns were used as basis for designing a Japanese version, which was finally approved in 1935 as 93 Shiki 13 mm Kiju. Mount specifications: maximum rate of fire – 474 rounds per minute, minimum – 425 round/min, theoretical – 450 round/min, effective – 250 round/min. The mount could be operated manually, single mount weighed 213 kg.
Another machine gun mounted on battlecruisers and battleships was the 7.7 mm gun, purchased in Great Britain and adopted in 1926. Its specifications are presented in Table 18.

Torpedo armament

The torpedo armament of the Kongō class battlecruisers – after their commissioning – comprised eight submerged 53 cm (type A) torpedo launchers, four of which were installed in the bow section and amidship, four in the stern section at the rudder shafts. The ships carried a load of twenty four 53 cm torpedoes type 44 Shiki 2 Go. During the first modernization, four launchers were removed from Kongō, Haruna and Kirishima. The amount of torpedoes taken aboard was reduced to 12. During the second modernization, all submerged launchers were removed as they were of little use for combat operations. The 6 Nen Shiki torpedo, approved in 1917, weighed 1,432 kg, its warhead was filled with 203 kg of Shimose charge. It was powered by twin-cylinder, double-acting engine similar to the Whitehead design, propelled by two four-blade, counter-rotating propellers mounted on a single shaft. Extreme length was 6,840 mm, diameter 533 mm. The torpedo’s range was 15,500 metres at 26 knots, 10,000 m at 32 knots and 7,000 m at 37 knots.


Regular complement of the Kongō class battlecruisers, in the first period of their service – according to the Confidential Navy Directive (CND) No 356 from December 1, 1914 – consisted of 52 officers, 26 ensigns, 259 non-commissioned officers, 922 (Kongō) and 942 (other units) sailors. The full complement was 1,259 (Kongō) and 1,279 (other units). First changes in crew composition took place in 1920. According to the CND No 267 from August 1, 1920, the complement comprised 38 officers, 16 officers assigned to coordinate the ships’ combat operations with other formations, 20 ensigns, 274 non-commissioned officers and 988 sailors. The complement was changed again in 1927. The Confidential Navy Directive number 91 from April 1, 1927 introduced 1,309 strong crew for Kongō and Hiei and 1,112 for Haruna and Kirishima. Another complement change took place in 1932 and concerned only Hiei, which after decommissioning, had only 826 sailors. According to the CND No 328 from December 1, 1932,  the crew was constituted of 30 officers, 12 officers assigned to coordinate the ships’ combat operations with other formations, 12 ensigns, 198 non-commissioned officers and 574 sailors. The units’ complements were changed for the last time in 1937. This time, the average complement aboard the fast battleships was 1,250 sailors. The CND number 169 from April 23, 1937, determined complements for each unit setting the number of officers to 47, 16 officers assigned to coordinate the ships’ combat operations with other formations and 15 ensigns. The biggest changes affected non-commissioned officers and sailors. Detailed data concerning numbers and composition of crews of individual units is presented in Table 19.



1 T (long ton) = 1,016 ton
2    More information concerning the ships’ modernization is presented in a separate chapter.
3    The gun was renamed to  45 Kōkei 41 Nendo Shiki 36cm Hō on October 5, 1917.
4    On November 5, 1917, the gun was renamed to 40 Kōkei 8 cm Kōkaku hō and again, on March 29,1920, to 40 Kōkei 3 Nen Shiki 8 cm Kōkaku hō (Kōkaku hō – high elevation)
5    Tan – short
6    Smaller guns were designated as follows:  Kōsha-Hō – anti-aircraft gun (with high elevation angle), Kiju – machine gun, Sokusha-hō – quick firing gun.


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3D15 Haruna okladka


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