# Operation Cartwheel

Operation Cartwheel (1943 – 1944) was a major military operation undertaken by the Allies in the Pacific theatre of World War II. The ultimate goal of Cartwheel was to neutralize the major Japanese base at Rabaul. The operation was directed by the Supreme Allied Commander in the South West Pacific Area (SWPA), General Douglas MacArthur, whose forces had advanced along the northeast coast of New Guinea and occupied nearby islands. Allied forces from the South Pacific Area, under Admiral William Halsey, advanced through the Solomon Islands toward Bougainville. The Allied forces from Australia, the Netherlands, New Zealand, the United States, and various Pacific Islands took part in the operation.

## Background

Japanese forces had captured Rabaul, on the island of New Britain in the Territory of New Guinea, from Australian forces in February 1942. Rabaul became a major forward base for Japanese forces in the South Pacific, and in turn became the main objective for Allied forces in the area. MacArthur formulated a strategy known as the Elkton Plan to capture Rabaul, using bases in Australia and New Guinea as staging points. Meanwhile, Admiral Ernest J. King, the Chief of Naval Operations, proposed a plan with similar elements but under US Navy command. Army Chief of Staff George C. Marshall, whose main goal was for the US to concentrate its efforts against Nazi Germany in Europe and not against the Japanese in the Pacific, proposed a compromise in which the drive towards Rabaul would be divided into three stages; the first under Navy command, and the latter two under MacArthur's direction and the control of the Army. This strategic plan, which was never formally adopted by the US Joint Chiefs of Staff but was ultimately implemented in practice, called for the following:
* Capturing Tulagi (and later Guadalcanal) and the Santa Cruz Islands (Operation Watchtower)
* Capturing the northeastern coast of New Guinea and the central Solomons
* Reducing Rabaul and surrounding Japanese bases
The protracted battle for Guadalcanal, followed by the unopposed seizure of the Russell Islands (Operation Cleanslate) on 21 February 1943, resulted in Japanese attempts to reinforce the area by sea. MacArthur's air forces countered in the Battle of the Bismarck Sea from 2–5 March 1943. The disastrous losses suffered by the Japanese prompted Admiral Isoroku Yamamoto to initiate Operation I-Go, a protracted series of air attacks against Allied airfields and shipping at both Guadalcanal and New Guinea, during which Japanese naval air strength was significantly attrited. Yamamoto was killed on 18 April 1943 when his plane was shot down over the Solomon Islands.

## Implementation

On 12 February 1943 MacArthur presented Elkton III, his revised plan for seizing Rabaul before 1944. It called for the US Army forces under his command to advance on northeastern New Guinea and western New Britain, and for Admiral William F. Halsey Jr., commander of the South Pacific Area, to attack the central Solomon Islands. The plan required seven more divisions than were already in the theatre, which raised objections from the British. The US Joint Chiefs responded with a directive that approved the plan if forces already in the theatre or en route were used, and implementation of the plan was delayed by 60 days. Elkton III then became Operation Cartwheel.

### Operations

Cartwheel identified 13 proposed subordinate operations and set a timetable for their launching. Of the thirteen, Rabaul, Kavieng, and Kolombangara were eventually dismissed as too costly or unnecessary; only 11 were actually undertaken (whereas the Green Islands, only 117 miles from Rabaul, were substituted for Kavieng):
* Operation Chronicle – 30 June 1943
** Woodlark Island (112th Cavalry Regiment)
** Kiriwina (158th Regimental Combat Team RCT US)
* Operation Toenails – 30 June 1943
** New Georgia (43d Infantry Division US) – 30 June 1943
** Segi Point, New Georgia (4th Marine Raider Battalion US) – 21 June 1943
** Rendova (169th and 172nd RCT's US) – 30 June 1943
** Zanana, New Georgia (169th and 172nd RCT's US) – 5 July 1943
** Bairoko, New Georgia (4th Marine Raider Battalion US) – 5 July 1943
** Arundel Island (172nd RCT, 43rd Infantry Division US) – 27 August 1943
* Vella Lavella (35th RCT, 25th Infantry Division US, 3rd Division New Zealand) – 15 August 1943
* Operation Postern – 5 September 1943
** Lae, New Guinea (9th and 7th Division Australia, 503rd Parachute Infantry Regiment US)
* Operation Goodtime – 27 October 1943
** Treasury Islands (8th Brigade New Zealand)
* Operation Blissful – 28 October 1943
** Choiseul Island (2nd Marine Parachute Battalion US)
* Operation Cherryblossom – 1 November 1943
** Bougainville (3d Marine Division US, 37th Infantry Division US)
* Operation Dexterity
** Arawe, New Britain (112th Cavalry US) – 15 December 1943
** Cape Gloucester (1st Marine Division US) – 26 December 1943
** Saidor (32nd Infantry Division US) – 2 January 1944
* Green Islands - 15 February 1944 (3rd Division New Zealand)
* Admiralty Islands – 29 February 1944 (1st Cavalry Division US)
* Emirau Island – 20 March 1944 (4th Marine Regiment US)
The New Guinea Force, under General Thomas Blamey, was tasked with thrusting eastward on mainland New Guinea. The US 6th Army, under General Walter Krueger, was ordered to seize Kiriwina, Woodlark, and Cape Gloucester. These land forces would be supported by Allied air units under Lieutenant General George Kenney and naval units under Vice Admiral Arthur S. Carpender.
In the midst of Operation Cartwheel, the Joint Chiefs met with President Franklin Roosevelt and British Prime Minister Winston Churchill at the Quadrant Conference in Quebec City in August 1943. There, the decision was made to bypass and isolate Rabaul rather than attempting to capture the base, now garrisoned by tens of thousands of Japanese troops. Soon afterward, the decision was made to bypass Kavieng as well. Although initially objected to by MacArthur, bypassing Rabaul instead of neutralizing it meant that his Elkton plan had been functionally achieved. After invading Saidor MacArthur moved on to his Reno Plan, an advance across the north coast of New Guinea to Mindanao. This campaign, which stretched into 1944, showed the effectiveness of major Japanese force concentrations in favor of severing Japanese lines of supply and communication to more isolated island garrisons.

### Neutralisation of Rabaul

The Japanese Navy attempted to bolster Rabaul's defenses by requisitioning hundreds of carrier aircraft from Japanese carriers based at Truk in December 1943. This proved to be a costly strategic miscalculation, as Allied planes shot down between 200–300 Japanese carrier aircraft during raids on Rabaul, stripping Japan of irreplaceable veteran carrier pilots. Japan's highly selective pilot training program was unable to cope with the casualties incurred from mid-1942 until early 1944, including during Operation Cartwheel, and could not produce enough trained aircrew to replace mounting losses. The result was a gradual degradation of the IJN's existing naval aviation arm, a trend that contributed to the catastrophic Japanese naval defeat at the Battle of the Philippine Sea in June 1944.
The erosion of Japanese strength in the Solomons led directly to the Admiralty Islands campaign, which was carried out in late February 1944, after the Allies had confirmed that the Japanese air threat from Rabaul had been effectively neutralized.
From February 1944 onwards, the Japanese declined to provision Rabaul with fighters or bombers for the rest of the war, mostly due to non-stop bombing of the base by land-based Allied airplanes only a few hundred miles away. The Japanese evacuated 120 aircraft to Truk on 19 February in an attempt to replace carrier aircraft destroyed defending Rabaul. The Japanese attempted to evacuate valuable by sea on 21 February, but their transport ship, the Kokai Maru, was sunk by Allied bombers. The Japanese garrison at Rabaul became completely isolated, as their supplies dwindled and Allied domination of the seas and skies rendered reinforcement impossible. Some 70,000 Japanese troops remained trapped at Rabaul by the time Japan surrendered in August 1945.