Operation Mo
| Operation Mo | |
|---|---|
 | |
| Planned | April 1942 |
| Objective | Occupation of Port Moresby |
| Outcome | Abandoned following the Battle of the Coral Sea |
Operation Mo (MO作戦, Mo Sakusen) 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 United States.
The plan was developed by the
Background
When the Japanese Navy was planning the
Strategy
 | This section needs additional citations for verification. (February 2012) |
The Directive of Operation Mo was conceived in 1938, but with no specific time for its execution, pending earlier successes in the southern area during the first and second phases of the conquest.
In April 1942, the operation was organized into four large actions and was approved by the Army and Navy General Staffs:
- On 3 May, the Light Task Force occupied the port of Tulagi, near Guadalcanal in the Solomon Islands, to establish a seaplane base and a base for operations in the Coral Sea area. The same force was to take Nauru and Banaba (Ocean Island) for their valuable phosphate deposits.
- The South Seas Detachment was to disembark in Port Moresby on 10 May, with another force occupying territory in the Louisiade Archipelago for another seaplane base.
- Another objective of the South Sea Detachment was Operation FS, the assault on New Caledonia, Fiji, and Samoa. IGHQ assigned a new double objective: capture and secure Port Moresby, in cooperation with the Navy; and seize strategic points of opportunity in eastern New Guinea.
- Another important Naval force, departing from Thursday Island to the north of Cape York.
- The Japanese had one Air Naval land-based fleet detached in Rabaul, Lae, Salamaua and Buna. This Air fleet executed the air strikes against Port Moresby on 5 May and 6 May, in preparation for the Japanese landing on 7 May.
Japanese planners took into account an Allied response to the operation by detaching one task force to the west of parallel between of
A Japanese message on 9 April 1942 indicated that the "RZP Campaign" against Port Moresby was to be an invasion, not an air raid, and which would isolate Australia from America. USN codebreaker Rudy Fabian at
Order of battle
| This section needs additional citations for verification. (February 2012) |
The Tulagi assault force, led by Rear Admiral Kiyohide Shima, was composed of the following units:
- Minelayer-cruiser Okinoshima
- Seaplane tender Kiyokawa Maru
- Destroyers Kikuzuki, Minazuki, Mochizuki and Yūzuki
- two transports
- smaller support vessels
The Port Moresby occupation force, led by Rear Admiral Sadamichi Kajioka, was composed of the following units:
- Light cruiser Yūbari
- Destroyers Mutsuki, Yayoi, Uzuki, Asanagi, Oite and Yūnagi
- Minelayers and sea patrol vessels
- Seaplane tender Kamikawa Maru
- Minelayer Tsugaru
Supporting these operations and intercepting any Allied interference, Rear Admiral
- Light carrier Shōhō
- Heavy cruisers Aoba, Kinugasa, Kako and Furutaka
- Light cruisers Tenryū, Tatsuta
- Destroyer Sazanami
During the course of operation,
- Fleet carriers Shōkaku and Zuikaku
- Heavy cruisers Myōkō and Haguro
- Destroyers Asashio, Arashio, Arare, Kagerō, Shiranui and Kasumi
- Auxiliary vessels
Supporting this force was the 25th Air Fleet, (Yokohama Air Corps) led by Rear Admiral
Execution
The Tulagi assault force began their landings on Tulagi on 3 May. On 4 May 1942, troopships bearing the South Seas Detachment set sail southward from Rabaul for Port Moresby. This same day US aircraft from Yorktown attacked the Tulagi assault force, inflicting heavy damage, but were unsuccessful in preventing the occupation of Tulagi, Gavutu, and Tanambogo islands.
Three days later, as a naval engagement appeared to be brewing in the Coral Sea, the Japanese Moresby transports immediately veered back to the north, in order to avoid combat. The resulting Battle of the Coral Sea inflicted significant aircraft losses on the Fourth Fleet, Shōhō was sunk, and Shōkaku was damaged. Air groups from the two carriers, including the relatively undamaged Zuikaku, suffered such sizable losses, it was necessary they return to Japan to re-equip and train.
The Japanese abandoned their plans to land the South Seas Detachment directly at Port Moresby from the sea. The Japanese Army was making new preparations for combat when, on 11 July, High Command ordered the suspension of Operation FS the projected actions against New Caledonia, Fiji, and Samoa, after the remaining Japanese carrier strength was destroyed at the Battle of Midway.
These battles prevented the Japanese landings against Port Moresby. Instead the Japanese army commenced an ultimately unsuccessful campaign to take Port Moresby with an overland approach across the Owen Stanley Range via the Kokoda Track.
Citations
- ^ Dufty 2017, pp. 123–128.
References
- Bullard, Steven (translator) (2007). Japanese army operations in the South Pacific Area New Britain and Papua campaigns, 1942–43. Canberra: Australian War Memorial. )
- Dufty, David (2017). The Secret Code-Breakers of Central Bureau. Melbourne, London: Scribe. ISBN 9781925322187.
- Japanese Demobilization Bureaux (1966). Japanese Operations in the Southwest Pacific Area. Volume II Part I. Reports of General MacArthur. United States Army. Archived from the original on 2008-01-25. Retrieved 2008-07-17.
- ISBN 0-252-06995-1.
- Rottman, Gordon (2005). Japanese Army in World War II. Conquest of the Pacific 1941–42. Battle Orders. Duncan Anderson (consultant editor). Oxford: Osprey. ISBN 1-84176-789-1.