| Katō Kanji | |
| Honorific Suffix: | Senior Second Rank |
| Native Name: | 加藤寛治 |
| Native Name Lang: | jpn |
| Birth Date: | 23 December 1870 |
| Birth Place: | Fukui Domain, Japan |
| Death Place: | Atami, Shizuoka, Japan |
| Serviceyears: | 1891–1935 |
| Rank: | Admiral |
| Commands: | Tsukuba, Ibuki, Hiei, Naval Gunnery School, 5th Squadron, Naval War College, Vice-chief of Navy General Staff, 2nd Fleet, Yokosuka Naval District, Combined Fleet, 1st Fleet, Chief of Navy General Staff |
| Battles: |
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| Awards: | Order of the Crown of Italy |
Katō Hiroharu, alternatively named Katō Kanji (23 December 1870 – 9 February 1939), was a Japanese naval officer during the Russo-Japanese War and World War I. The first name 'Kanji' was used in his later life after he became famous, likely just before he was promoted to rear-admiral. He served as the Chief of Navy General Staff from 22 January 1929 to 11 June 1930.
Katō Hiroharu was born in Fukui City in Fukui on 2 November in the 3rd year of Meiji[1] (23 December 1870) as the eldest son of one of the first navy officers, Katō Naokata, of Fukui Domain in Imperial Japan before the Abolition of the han system.[2] On 17 July 1891, he graduated top of the class from Imperial Japanese Naval Academy, 18th class. He was assigned to cruiser Naniwa as a cadet as of 20 May 1892 and experienced two tours to Kingdom of Hawaii. While at Honolulu on the second tour, he was promoted to ensign on 1 March 1894. He was assigned as a navigator on cruiser Hashidate. After returning to Yokosuka Naval Base, he completed the Gunnery training program on corvette Ryūjō on 1 March 1896, which later became the Gunnery School of Naval War College. At the same time, he was assigned as a navigator on cruiser Chiyoda.
In February 1896, he married Murata Chiyoko from Fukui Domain, and on 24 October 1896, he was appointed as a member of the receiving commission sent to London for battleship Fuji.[2] Promoted to squad leader on Fuji, Chief Navigation Officer of IJN Tatsuta, and then assigned to Consulate General of Japan in Saint Petersburg.
He entered into Russo-Japanese War in 1904 as the Chief Gunnery Officer of IJN Asahi and experimented with a salvo-firing central control of main guns during the Battle of the Yellow Sea on 10 August 1904, contributing to the killing of admiral Wilgelm Vitgeft and his staff onboard Russian flagship Tsesarevich after the Japanese fleet flagship Mikasa handed over the leading battle position to Asahi. His primitive voice-command control system was adopted by the entire Combined Fleet, and he was promoted to the Chief Gunnery Officer of flagship Mikasa in March 1905.
He was a naval attaché at the Embassy of Japan in London in 1909. He had opposed the signing of the 1930 Treaty of London, which established limitations on arms between Japan, the United States and Great Britain. In 1930 he resigned rather than attend a dinner in honour of US Ambassador William Richards Castle Jr., in protest against the naval restrictions negotiated with him.[3] Kato fought against the treaty limitations, and the treaty of 1936, finally dying after writing his memoirs, widely regarded as a treatise on why Japan was disadvantaged by the treaties. His actions prevented him from advancing in rank and probably cost him a seat in the government. He had an active antagonistic relationship with Yamamoto, who used his influence to prevent Kato from advancing.[4]