was a large

minelayer A minelayer is any warship, submarine or military aircraft deploying explosive mines. Since World War I the term "minelayer" refers specifically to a naval ship used for deploying naval mines. "Mine planting" was the term for installing controll ...

of the

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, when it was dissolved following Japan's surrender ...

(IJN), which was in service during the early stages of

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. She was named after the Okinoshima Island in the

Sea of Japan The Sea of Japan is the marginal sea between the Japanese archipelago, Sakhalin, the Korean Peninsula, and the mainland of the Russian Far East. The Japanese archipelago separates the sea from the Pacific Ocean. Like the Mediterranean Sea, it h ...

. She was the largest purpose-built minelayer in the IJN and the first Japanese minelayer to be equipped with a reconnaissance

seaplane A seaplane is a powered fixed-wing aircraft capable of takeoff, taking off and water landing, landing (alighting) on water.Gunston, "The Cambridge Aerospace Dictionary", 2009. Seaplanes are usually divided into two categories based on their tec ...

Building

Following the ratification of the

London Naval Treaty The London Naval Treaty, officially the Treaty for the Limitation and Reduction of Naval Armament, was an agreement between the United Kingdom, Japan, France, Italy, and the United States that was signed on 22 April 1930. Seeking to address is ...

, the Imperial Japanese Navy decided to retire its existing obsolete minelayers, the former

cruiser A cruiser is a type of warship. Modern cruisers are generally the largest ships in a fleet after aircraft carriers and amphibious assault ships, and can usually perform several roles. The term "cruiser", which has been in use for several hu ...

s , and . A replacement was budgeted under the ''Maru-1'' Supplementary Naval Expansion Budget of 1931. The new vessel was to be of unprecedented size, thus overcoming the shortcomings of previous minelayers in the Japanese inventory in terms of range and capacity. In addition to carrying 600 Type 6

naval mine A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, any ...

s, the new ship had the same guns as were used on the , and also was equipped with an

aircraft catapult An aircraft catapult is a device used to allow aircraft to take off from a very limited amount of space, such as the deck of a vessel, but can also be installed on land-based runways in rare cases. It is now most commonly used on aircraft carrier ...

, and a

Kawanishi E7K The Kawanishi E7K was a Japanese three-seat reconnaissance seaplane mainly in use during the 1930s. It was allocated the reporting name Alf by the Allies of World War II. Design and development In 1932 the Imperial Japanese Navy requested the K ...

reconnaissance seaplane. ''Okinoshima'' was launched by the Harima Shipyards (now part of

IHI Corporation , formerly known as , is a Japanese engineering corporation headquartered in Tokyo, Japan that produces and offers ships, space launch vehicles, aircraft engines, marine diesel engines, gas turbines, gas engines, railway systems, turbochargers ...

) in

Hyōgo Prefecture is a prefecture of Japan located in the Kansai region of Honshu. Hyōgo Prefecture has a population of 5,469,762 () and has a geographic area of . Hyōgo Prefecture borders Kyoto Prefecture to the east, Osaka Prefecture to the southeast, an ...

, Japan on November 14, 1935, and was commissioned into service on 30 September 1936.

Operational history

During the late 1930s, ''Okinoshima'' was assigned as

flagship A flagship is a vessel used by the commanding officer of a group of naval ships, characteristically a flag officer entitled by custom to fly a distinguishing flag. Used more loosely, it is the lead ship in a fleet of vessels, typically the fi ...

of a

destroyer In naval terminology, a destroyer is a fast, manoeuvrable, long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against powerful short range attackers. They were originally developed in ...

squadron, and made numerous survey missions to the

Marshall Islands The Marshall Islands ( mh, Ṃajeḷ), officially the Republic of the Marshall Islands ( mh, Aolepān Aorōkin Ṃajeḷ),'' () is an independent island country and microstate near the Equator in the Pacific Ocean, slightly west of the Internati ...

Caroline Islands The Caroline Islands (or the Carolines) are a widely scattered archipelago of tiny islands in the western Pacific Ocean, to the north of New Guinea. Politically, they are divided between the Federated States of Micronesia (FSM) in the centra ...

and

Marianas The Mariana Islands (; also the Marianas; in Chamorro: ''Manislan Mariånas'') are a crescent-shaped archipelago comprising the summits of fifteen longitudinally oriented, mostly dormant volcanic mountains in the northwestern Pacific Ocean, betw ...

in the Japanese

South Seas Mandate The South Seas Mandate, officially the Mandate for the German Possessions in the Pacific Ocean Lying North of the Equator, was a League of Nations mandate in the "South Seas" given to the Empire of Japan by the League of Nations following Wo ...

, seeking potential sites for

bases, and transporting naval mines for future use. At the time of the

attack on Pearl Harbor The attack on Pearl HarborAlso known as the Battle of Pearl Harbor was a surprise military strike by the Imperial Japanese Navy Air Service upon the United States against the naval base at Pearl Harbor in Honolulu, Territory of Hawaii, j ...

in December 1941, ''Okinoshima'' was serving as flagship for Admiral

Kiyohide Shima was an admiral in the Imperial Japanese Navy during World War II. Biography A native of Miyazaki prefecture, Shima was a graduate of the 39th class of the Imperial Japanese Naval Academy in 1911, ranking 69th out of 148 cadets. As a midshipman, h ...

in Operation ''Gi'' (the

invasion An invasion is a military offensive in which large numbers of combatants of one geopolitical entity aggressively enter territory owned by another such entity, generally with the objective of either: conquering; liberating or re-establishing con ...

of the

Gilbert Islands The Gilbert Islands ( gil, Tungaru;Reilly Ridgell. ''Pacific Nations and Territories: The Islands of Micronesia, Melanesia, and Polynesia.'' 3rd. Ed. Honolulu: Bess Press, 1995. p. 95. formerly Kingsmill or King's-Mill IslandsVery often, this n ...

) and had deployed from

Jaluit Jaluit Atoll ( Marshallese: , , or , ) is a large coral atoll of 91 islands in the Pacific Ocean and forms a legislative district of the Ralik Chain of the Marshall Islands. Its total land area is , and it encloses a lagoon with an area of . Most ...

with a

Special Naval Landing Force The Special Naval Landing Forces (SNLF; ja, 海軍特別陸戦隊, Kaigun Tokubetsu Rikusentai) were naval infantry units of the Imperial Japanese Navy (IJN) and were a part of the IJN Land Forces. They saw extensive service in the Second Sino ...

(SNLF) embarked. From 9–10 December, ''Okinoshima'' supported the Japanese landings on Makin and on

Tarawa Tarawa is an atoll and the capital of the Republic of Kiribati,Kiribati
''

Abaiang Abaiang, also known as Apaiang, Apia, and in the past, Charlotte Island, in the Northern Gilbert Islands, is a coral atoll of Kiribati, located in the west-central Pacific Ocean. Abaiang was the island of the first missionary to arrive in the ...

. ''Okinoshima'' was at Truk on 1 January 1942. In January 1942, under the overall command of Admiral

Sadamichi Kajioka was an admiral in the Imperial Japanese Navy during World War II. He directed Japanese forces involved in the Battle of Wake Island. Biography A native of Ehime prefecture, Kajioka graduated from the 39th class of the Imperial Japanese Naval Ac ...

, ''Okinoshima'' participated in "Operation R" (the invasion of

Rabaul Rabaul () is a township in the East New Britain province of Papua New Guinea, on the island of New Britain. It lies about 600 kilometres to the east of the island of New Guinea. Rabaul was the provincial capital and most important settlement in ...

) landing Japanese troops at Blanche Bay, Rabaul on the night of 22/23 January 1942. On 1 February, ''Okinoshima'' was officially reassigned to the

South Seas Force The 4th Fleet was a fleet of the Imperial Japanese Navy. The Fourth Fleet designation was used during three separate periods. The initial designation was for a group of ships that were assigned to work together during the Russo-Japanese conflict a ...

. On 5 March, ''Okinoshima'', under the overall command of Admiral

Kuninori Marumo , was an admiral in the Imperial Japanese Navy during World War II. Biography Marumo was a native of Nagano prefecture. He graduated from the 40th class of the Imperial Japanese Naval Academy in 1912, ranked 47th out of 144 cadets. As a midsh ...

, was assigned to "Operation SR" (the invasion of

Lae Lae () is the capital of Morobe Province and is the second-largest city in Papua New Guinea. It is located near the delta of the Markham River and at the start of the Highlands Highway, which is the main land transport corridor between the Highl ...

and

Salamaua Salamaua () was a small town situated on the northeastern coastline of Papua New Guinea, in Salamaua Rural LLG, Morobe province. The settlement was built on a minor isthmus between the coast with mountains on the inland side and a headland. The c ...

New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...

). On 10 March, the invasion force was attacked by

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

aircraft from and , with ''Okinoshima'' suffering light damage. After repairs at Truk, on 28 April ''Okinoshima'' was appointed flagship for Admiral Shima's

Tulagi Tulagi, less commonly known as Tulaghi, is a small island——in Solomon Islands, just off the south coast of Ngella Sule. The town of the same name on the island (pop. 1,750) was the capital of the British Solomon Islands Protectorate from 18 ...

invasion force, which was part of "

Operation Mo or the Port Moresby Operation was a Japanese plan to take control of the Australian Territory of New Guinea during World War II as well as other locations in the South Pacific. The goal was to isolate Australia and New Zealand from the Allied ...

" (the invasion of Tulagi and

Port Moresby (; Tok Pisin: ''Pot Mosbi''), also referred to as Pom City or simply Moresby, is the capital and largest city of Papua New Guinea. It is one of the largest cities in the southwestern Pacific (along with Jayapura) outside of Australia and New Z ...

). The Tulagi assault force began their landings on Tulagi on 3 May, with ''Okinoshima'' successfully landing troops of the Kure 3rd SNLF. However, the invasion force was attacked on 4 May by aircraft from the USS ''Yorktown''. Several transports and the destroyer were sunk and ''Okinoshima'' suffered from a near miss, which resulted in her being towed to Rabaul for repairs.

Fate

On 10 May, ''Okinoshima'' departed Rabaul as part of "

Operation RY Operation RY was the Imperial Japanese plan to invade and occupy Nauru and Ocean islands in the south Pacific during the Pacific conflict of World War II. The operation was originally set to be executed in May 1942 immediately following Operat ...

", the invasion of

Nauru Nauru ( or ; na, Naoero), officially the Republic of Nauru ( na, Repubrikin Naoero) and formerly known as Pleasant Island, is an island country and microstate in Oceania, in the Central Pacific. Its nearest neighbour is Banaba Island in Ki ...

and Ocean Island. On 12 May 1942, off New Ireland, she was hit by two or three torpedoes from the American submarine USS ''S-42''. ''Okinoshima'' was taken under tow by the escorting destroyer , but capsized in St. George's Channel, in the

Bismarck Sea The Bismarck Sea (, ) lies in the southwestern Pacific Ocean within the nation of Papua New Guinea. It is located northeast of the island of New Guinea and south of the Bismarck Archipelago. It has coastlines in districts of the Islands Region, ...

at position . Most of the crew survived. ''Okinoshima'' was removed from the

navy list A Navy Directory, formerly the Navy List or Naval Register is an official list of naval officers, their ranks and seniority, the ships which they command or to which they are appointed, etc., that is published by the government or naval author ...

on 25 May 1942.

References

Notes

Books

* * * * *

External links

* * {{DEFAULTSORT:Okinoshima Minelayers of the Imperial Japanese Navy World War II mine warfare vessels of Japan Ships built by IHI Corporation 1935 ships Maritime incidents in May 1942 Shipwrecks in the Bismarck Sea Ships sunk by American submarines