Yokosuka Naval Arsenal: A Brief History

Uncommon Aircraft

1866 Yokosuka Works (横須賀製作所 - Yokosuka Seisakusho) established.

Late 1869 Yokosuka Naval Arsenal (横須賀海軍工廠 - Yokosuka Kaigun Kosho) established by the Imperial Japanese Navy, with French assistance, on Tokyo Bay south of Yokohama, tasked with naval shipbuilding, ship repairs, munitions storage and naval supply procurement.

1871 Renamed Yokosuka Shipyards (横須賀造船所 - Yokosuka Zosenjo) or Yokosuka Navy Yard; first drydock built.

August 1876 Imperial Japanese Navy organized into two strategic zones: eastern zone Tokai Chinjufu at Yokosuka and western zone Saikai Chinjufu at Nagasaki.

September 1876 Tokai Naval District relocated to Yokohama.

1884 Yokosuka Naval District (横須賀鎮守府 - Yokosuka Chinjufu) established, with territory including Tokyo Bay and the Pacific coasts of central and northern Honshu from Wakayama to Aomori prefectures.

June 1885 Bureau of Torpedo Warfare established at Yokosuka.

April 1886 Imperial Japanese Navy re-organized into five naval districts; Tokai Naval District relocated to Yokosuka as Yokosuka Naval District, with command over Yokosuka Naval Arsenal.

1889 Yokosuka Naval District renamed 1st Naval District (Dai-Ichi Kaigunku - 第一海軍区); Bureau of Mine Warfare established at Yokosuka.

1893 Naval mechanical engineering, torpedo warfare and naval artillery schools established at Yokosuka.

1907 Naval engineering and mine warfare schools established at Yokosuka.

1908 Naval medical center established at Yokosuka.

June 1912 Naval aviation facilities established at Yokosuka.

April 1913 Wireless communications facility established at Yokosuka.

May 1913 Aeroplane Factory created under Ordnance Department of Yokosuka Naval Arsenal. Early imported aircraft were assembled, repaired and modified, which led to limited aircraft production.

1914 The acronym "Yokosho" was first used to refer to the Yokosuka Naval Arsenal (from Yokosuka Kaigun Kosho).

1921 Naval Construction Department established at Yokosuka.

1 April 1927 Naval Air Headquarters established to manage all Imperial Japanese Navy aviation projects.

June 1930 Naval Communications School established at Yokosuka; Naval Mine School becomes independent.

1 April 1932 Naval Air Arsenal established at Yokosuka Naval Arsenal, under the command of the Naval Air Headquarters. The Yokosuka Kokutai (Oppama Naval Air Base) and Yokosuka Naval Arsenal Ordnance Department (which included the Aeroplane Factory, Aero-engine Factory and Flight Experiment Group) were merged into this new Naval Air Arsenal, along with the Kasumigaura Branch of the Naval Technical Research Institute; additionally, design engineers and draftsmen of the Hiro Arsenal were transferred to this new Naval Air Arsenal (effectively ending aircraft design at Hirosho). Referred to by the acronym "Kusho" (from Kaigun Kokusho). Various aircraft were designed up to the end of World War II, with production by various Japanese aircraft manufacturers, including Aichi, Hitachi, Hiro, Kawanishi, Mitsuibishi, Nakajima and Watanabe.

April 1934 Naval Aviation School established at Yokosuka.

1 April 1939 Naval Air Arsenal renamed Naval Air Technical Arsenal (Kaigun Koku-Gijutsu-Sho; acronym Kugisho).

15 February 1945 Naval Air Arsenal renamed 1st Naval Technical Arsenal (Dai-Ichi Kaigun Gijutsu-sho; acronym "Ichi-Gisho").

14 August 1945 Japanese surrender, end of World War II.

30 August 1945 Yokosuka Naval Arsenal surrenders to and is occuppied by Allied forces.

15 October 1945 Yokosuka Naval Arsenal officially abolished.

Late 1945 Commander Fleet Activities Yokosuka, Yokosuka Ship Repair Facility established by U.S. Navy; shipyard deactivated and equipment dispersed to Allies for war reparations.

May 1946 Marine Barracks, U. S. Fleet Activities, Yokosuka, established.

April 1947 Ship Repair Department established at Yokosuka Navy Base; dry docks and workshops re-activated to support U. S. Pacific Fleet.

January 1951 Naval Communications Facility established.

April 1951 Ship Repair Department redesignated Ship Repair Facility.

1960 Naval Communications Facility redesignated U. S. Naval Communications Station, Japan.

5 October 1973 USS Midway and carrier task group forward-deployed to Yokosuka.

August 1991 USS Midway replaced by USS Independence for forward-deployment to Yokosuka.

August 1998 USS Independence replaced by USS Kitty Hawk for forward-deployment to Yokosuka.

25 September 2008 USS Kitty Hawk replaced by USS George Washington for forward-deployment to Yokosuka.

Starting in the 1930s, the Imperial Japanese Navy assigned the letter "Y" designation to aircraft designs orignating from the Naval Air Arsenal. Here is a summary of aviation-related acronyms related to Yokosuka:

Acronym Meaning Timeframe
Yokosho Yokosuka Kaigun Kosho (Yokosuka Naval Arsenal) 1914 - 1 April 1932
Kusho Kaigun Kokusho (Naval Air Arsenal) 1 April 1932 - 1 April 1939
Kugisho Kaigun Koku-Gijutsu-Sho (Naval Air Technical Arsenal) 1 April 1939 - 15 February 1945
Ichi-Gisho Dai-Ichi Kaigun Gijutsu-sho (1st Naval Technical Arsenal) 15 February 1945 - 15 October 1945

It is quite common for English-language aviation references to refer to "Yokosuka" as an aircraft manufacturer/designer; however, it would be more correct and appropriate to use one of the above acronyms, depending on the time period referenced.

Example: The D4Y Suisei should be referred to as Kugisho D4Y Suisei, not Yokosuka D4Y Suisei.

Japan Imperial Japanese Navy
[ Japan | IJN ]

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© 1997-2013, Robert Beechy
Originally posted February 2013
Modified: 02/12/2013