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Operation RY

Operation RY

Map of the Coral Sea area with Nauru and Ocean (Banaba) islands in the top right corner.
Planned April 1942
Objective Occupation of Nauru and Ocean islands
Date 10 May and August 1942
Executed by Imperial Japanese Navy
Outcome Postponed on 15 May 1942;
completed successfully on 29–30 August 1942
Casualties 1 minelayer,
1 auxiliary ship sunk

Operation RY (Invasion of Nauru & Ocean Island) was the name of 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 Operation MO and before Operation MI, which resulted in the Battle of Midway. The primary reason for the operation was to exploit the islands' supplies of phosphate. After a postponement due to interference by enemy forces, the operation was completed in August 1942.


  • Background 1
  • First invasion attempt 2
  • Second Invasion Attempt 3
  • Base Development 4
  • Allied Attacks 5
  • References 6
    • Books 6.1
    • Web 6.2


Before and during World War II, Nauru and Ocean Island were isolated but rich with phosphate deposits. The islands were under Australian mandate control with the British Phosphate Commissioners (BPC) running the phosphate mining. The phosphate deposits were mined for making ammunition, explosives and fertilizers.

The German auxiliary cruisers Orion and Komet sank five merchant ships and bombarded the island causing damage to the phosphate mining, disrupting the allies production of phosphate. Following the raids the Australian Commonwealth Naval Board requested that the British Admiralty agree to redeploy Australian naval units to meet the threat posed by raiders. The armed merchant cruiser HMAS Manoora arrived off Ocean Island on 4 January 1941, and Australian and New Zealand warships maintained a continual presence off the islands during the subsequent months and a naval company and two field guns were deployed to each island. The attacks also led to the introduction of convoys between Australia and New Zealand.

In late February 1942, as a Japanese invasion of Nauru and Ocean Island was feared, the Free French destroyer Triomphant departed the New Hebrides to evacuate both Nauru and Ocean Island. The ship arrived on 23 February and completed the evacuation without serious incident.

Although Operation MO was cancelled on 8 May 1942 immediately following the Battle of the Coral Sea, the Imperial Japanese Navy forces departed Rabaul and Bougainville on 11 May to execute the RY operation.

First invasion attempt

On 11 May 1942, the Imperial Japanese invasion force, under the command of Rear Admiral Shima Kiyohide departed Rabaul consisting of the cruiser Tatsuta, the minelayers Okinoshima (flagship) and Tsugaru and destroyers Uzuki and Yūzuki, covered by 5th Cruiser Division, under the command of Rear Admiral Takeo Takagi, consisting of the heavy cruisers Myōkō and Haguro with the Destroyer Division 30 destroyers Ariake, Mochizuki, Shigure and Shiratsuyu. The invasion troops from the 6th Special Naval Landing Force (SNLF) and Kashima SNLF were carried by the transports Kinryū Maru and Takahata Maru.[1]

While steaming through driving rain off , New Ireland, by S-44.[4] She sank at 1440 at .

In spite of the loss of Okinoshima, the rest of the Japanese forces continued with the operation. As these forces were en route, however, a Japanese reconnaissance aircraft from Tulagi sighted the United States Navy aircraft carriers USS Enterprise and Hornet heading towards Nauru. The two US carriers, acting on intelligence taken from intercepted Japanese communications, had been sent to the area as a feint to try to stop the Japanese operation.

The feint was successful. Fearing the threat posed by the US carriers to the RY forces, which did not have air cover, the Japanese cancelled the operation on 15 May and the naval forces returned to Rabaul.

Second Invasion Attempt

A second invasion force departed Truk on 26 August 1942, consisting of the cruiser Yūbari, the destroyers Oite, Yūzuki, Ariake, Yūgure and Yūnagi, and the transport Hakozaki Maru.

The landing forces landed on Nauru on 29 August and Ocean Island on 30 August unopposed.

Base Development

Japanese forces occupied the two islands until the end of the war, but became increasingly isolated as the war progressed.

Allied Attacks

During the Japanese occupation of Nauru, American aircraft repeatedly bombed the island's facilities.


  1. ^ Bullard, p. 57.
  2. ^ "Battle of the Coral Sea". Naval History & Heritage. US Navy. Retrieved 6 June 2011. 
  3. ^ "USN Ships USS S-42 (SS-153)". NAVAL HISTORICAL CENTER. US Navy. Retrieved 6 June 2011. 
  4. ^ "USN Ships USS S-44 (SS-155)". NAVAL HISTORICAL CENTER. US Navy. Retrieved 6 June 2011. 


  • Brown, David (1990). Warship Losses of World War Two. Naval Institute Press.  
  • Lundstrom, John B. (2006). Black Shoe Carrier Admiral: Frank Jack Fletcher at Coral Sea, Midway, and Guadalcanal. Annapolis, Maryland: Naval Institute Press.  
  • Lundstrom, John B. (2005). The First Team: Pacific Naval Air Combat from Pearl Harbor to Midway (New ed.). Annapolis, Maryland, U.S.A.: Naval Institute Press.  
  • Willmott, H. P. (2002). The War with Japan: The Period of Balance, May 1942 – October 1943.  


  • Bullard, Steven (translator) (2007). Japanese army operations in the South Pacific Area New Britain and Papua campaigns, 1942–43. Canberra: Australian War Memorial.   (translation of excerpts from the Senshi Sōshō)
  • Hackett, Bob; Kingsepp, Sander (2003). "HIJMS Furutaka: Tabular Record of Movement". Junyokan. Retrieved 10 May 2009. 
  • Hackett, Bob, Sander Kingsepp, and Peter Cundall (1998–2007). "HIJMS Myoko: Tabular Record of Movement". Junyokan!. 
  • Hackett, Bob, and Sander Kingsepp (1998–2007). : Tabular Record of Movement"Okinoshima"IJN Minelayer . Fusetsukan!. 
  • Hackett, Bob, Sander Kingsepp, and Peter Cundall (1998–2007). "HIJMS Tatsuta: Tabular Record of Movement". Junyokan!. 
  • Hackett, Bob, Sander Kingsepp, and Peter Cundall (1998–2007). "IJN Tsugaru: Tabular Record of Movement". Fusetsukan!. 
  • McCarthy, Dudley (1959). Volume V – South–West Pacific Area – First Year: Kokoda to Wau.  
  • Nevitt, Allyn D. (1998–2009). "IJN Uzuki: Tabular Record of Movement". Long Lancers!. 
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