Operation Cartwheel

• 1. Introduction

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  Operation Cartwheel, launched in 1943, had a single declared objective: neutralize the Japanese base at Rabaul. That base sat on the northeastern tip of New Britain. Japan had turned it into the nerve center of its entire South Pacific presence. What followed was not a single battle but a chain of operations fought across jungle, reef, and ocean. Together, they would eventually render Rabaul harmless without the Allies ever storming its walls.

  Several questions run through what follows. How did rival American commanders, one from the Army and one from the Navy, forge a workable plan from competing visions? What did it cost to fight through the Solomon Islands and New Guinea, island by island, against defenders who held every terrain advantage? And how did a catastrophic blunder by Japan's own naval commanders decide Rabaul's fate more effectively than any Allied assault? The forces arrayed for this campaign came from Australia, the Netherlands, New Zealand, and Pacific Island territories, alongside those of the United States.

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• 2. Rival Plans, Shared Goal

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  Japanese forces captured Rabaul from Australian defenders in February 1942. The harbor could shelter a fleet. The airfields extended Japan's aircraft across the Bismarck Sea. From that position, Japan could threaten Allied supply lines to Australia and project power across the South Pacific.

  General Douglas MacArthur commanded Allied forces in the Southwest Pacific Area. He devised the Elkton Plan, a methodical advance to seize Rabaul using bases in Australia and New Guinea. Admiral Ernest J. King, Chief of Naval Operations, favored a similar advance but insisted on Navy command. Army Chief of Staff George C. Marshall, whose priority was defeating Nazi Germany, proposed a compromise. It would divide the drive toward Rabaul into three stages. The first would fall under Navy command. The second and third would answer to MacArthur.

  The US Joint Chiefs never formally adopted this framework. They implemented it anyway. MacArthur's revised version, Elkton III, was presented on the 12th of February 1943. It required seven additional divisions beyond those already in the theatre. The British raised objections. The Joint Chiefs authorized the plan only with forces already on hand and delayed the start by 60 days. Elkton III became Operation Cartwheel.

  The seizure of the Russell Islands in Operation Cleanslate on the 21st of February 1943 prompted Japan to attempt reinforcement by sea. MacArthur's aircraft countered in the Battle of the Bismarck Sea, fought from the 2nd to the 5th of March 1943. The Japanese losses were severe. Admiral Isoroku Yamamoto responded with Operation I-Go, a prolonged series of air attacks on Allied airfields and shipping at Guadalcanal and New Guinea. The raids wore down Japanese naval air strength over weeks. On the 18th of April 1943, Yamamoto was killed when his aircraft was shot down over the Solomon Islands. The campaign he had sought to derail had not yet begun.

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• 3. A Different Kind of Fighting

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  The island of New Georgia was defended by 10,500 Japanese troops, dug into terrain that favored the defender at every turn. Rear Admiral Richmond K. Turner's III Amphibious Force was assigned to get Allied forces ashore. Detachments of the 4th Marine Raider Battalion arrived first, landing at Segi on the 21st of June 1943.

  The main landings began on the 30th of June. Major General John H. Hester's 43rd Infantry Division came ashore at Viru, Wickham Anchorage, and Rendova. Further landings followed at Zanana on the 2nd of July and at Bairoko on the 5th of July. The target was the airfield at Munda Point.

  Heat, rain, and dense foliage slowed every advance. The Japanese commander, Major General Minoru Sasaki, used the terrain expertly. The 43rd Division struggled to reach Munda Point. Major General Oscar Griswold's XIV Corps eventually assumed control of the operation, bringing the 25th and 35th Infantry Divisions into the fight. On the 25th of July, Griswold launched a major offensive against Munda Point.

  The 43rd Division captured Munda Airfield on the 5th of August. The campaign's cost far exceeded what planners had predicted, with 1,094 Allied dead and 3,873 wounded. Japanese losses stood at 2,483 men killed, along with five destroyers and a light cruiser.

  After evacuating New Georgia, Sasaki's forces retreated to Arundel, Baanga, and Kolombangara. Admiral Halsey chose not to attack the fortified garrison on Kolombangara. Instead, on the 15th of August, Allied forces landed on Vella Lavella. The American 25th and New Zealand 3rd Divisions carried the main assault. Fighting continued for nearly two months until the island was fully in Allied hands. When Vella Lavella fell, the base on Kolombangara became useless, and its garrison was forced to withdraw to Bougainville. Allied naval forces moved to intercept the retreating Japanese fleet on the 6th of October, but the evacuation could not be stopped.

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• 4. The New Guinea Front

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  Operation Chronicle, the first scheduled campaign of Cartwheel, ran from the 23rd to the 30th of June 1943. Units of the 112th Cavalry Regiment and the 158th Infantry Regiment landed unopposed on Woodlark and Kiriwina Islands. The goal was practical: build airfields from which the next stages of the advance could be supported.

  Operation Postern struck at Lae on the 4th of September. Forces of the Australian 9th Division under Major General George Wootten, backed by Vice Admiral Daniel E. Barbey's VII Amphibious Force, came ashore. The following day, the US Army's 503rd Parachute Infantry Regiment seized Nadzab Airport from the Japanese. Generals MacArthur and Kenney personally observed that operation from the air. By the 7th of September, the Australian 7th and 9th Divisions had converged on Lae. They defeated the Japanese 41st and 51st Divisions, forcing General Adachi to abandon the port.

  Operation Dexterity turned toward the western coast of New Britain. Vice Admiral Barbey's Task Force 76 landed the 112th Cavalry Regiment on the Arawe peninsula on the 15th of December. Eleven days later, the 1st Marine Division came ashore at Cape Gloucester and engaged the Japanese 17th Division in a battle for two airfields. On the 2nd of January 1944, the 32nd Infantry Division, which had performed poorly at the Battle of Buna-Gona, invaded Saidor. The initial landing went unopposed, but fighting continued until the 10th of February 1944. By the end of the campaign, 40 Americans and nearly 2,600 Japanese had been killed.

  MacArthur's advance along the New Guinea coast now pointed toward his Reno Plan. That plan aimed at driving across the north coast of New Guinea toward Mindanao in the Philippines.

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• 5. Bougainville

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  Admiral Halsey's next major objective was the island of Bougainville, where he intended to build bases for bombing attacks on Rabaul. Brigadier General Nathan F. Twining's AirSols force began striking Japanese airfields on the island in early October 1943.

  On the 27th of October, the New Zealand 8th Brigade captured the Treasury Islands in Operation Goodtime. The following day, the US 2nd Marine Parachute Battalion seized Choiseul Island in Operation Blissful.

  The invasion of Bougainville itself began on the 1st of November. Lieutenant General Alexander Vandegrift's 3rd Marine Amphibious Corps put 14,000 men ashore at Cape Torokina. Japanese counterattacks that night and the following day were beaten back. Throughout November, the US Seventh Fleet under Rear Admiral Theodore S. Wilkinson blocked Japanese attempts to reinforce Lieutenant General Harukichi Hyakutake's 17th Army.

  By December, the Americal Division under Brigadier General John R. Hodge had relieved the 3rd Amphibious Corps. Three airfields had been constructed on Bougainville by mid-December. Major General Griswold's XIV Corps assumed overall command on the 15th of December.

  Hyakutake had spent the winter building his forces. By March 1944, he had gathered 15,000 troops for a counteroffensive. It opened on the 8th of March and continued for two weeks. Griswold's forces repelled it. The engagement cost 263 Allied casualties and 10,000 Japanese casualties. The Allies had largely secured Bougainville by April 1944. Fighting on the island continued regardless until Japan surrendered, but the airfields that mattered to the campaign were already built and operational.

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• 6. The Final Moves

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  In August 1943, Allied leaders gathered at the Quadrant Conference in Quebec City. President Franklin Roosevelt, Prime Minister Winston Churchill, and the Joint Chiefs all attended. Rabaul's garrison had grown to tens of thousands of Japanese troops. A direct amphibious assault on those numbers, the planners concluded, would be too costly.

  The decision at Quebec was to bypass Rabaul rather than storm it. A second decision followed: Kavieng would also be bypassed. MacArthur initially resisted both. He eventually accepted them. Bypassing Rabaul achieved what the Elkton Plan had originally sought, and the campaign moved toward its concluding operations.

  On the 30th of January 1944, the New Zealand 30th Infantry Battalion conducted a reconnaissance landing on Nissan Island. Known also as Green Island, it lay only 117 miles from Rabaul. The full invasion followed on the 15th of February, led by Major General Harold Barrowclough's 3rd New Zealand Division. All Japanese soldiers on the island were killed. Nissan was secured in five days.

  The Admiralty Islands campaign, codenamed Operation Brewer, began on the 29th of February 1944. Brigadier General William C. Chase's 1st Cavalry Division landed at Hyane Harbor on Los Negros Island. They seized the beaches within four hours and captured Momote airfield the same day. General MacArthur observed the battle from the beach and decorated several soldiers there afterward. Reinforcements from the 7th Cavalry Regiment and 12th Regimental Combat Team arrived on the 4th and the 5th of March.

  Brigadier General Verne D. Mudge's 2nd Cavalry Regiment landed on Manus Island on the 15th of March and secured Lorengau airfield within two days. The 7th Cavalry Regiment captured Hauwei. The Admiralty Islands campaign killed 326 Allied troops and 3,280 Japanese troops.

  Admiral Halsey directed a naval bombardment of Kavieng beginning on the 20th of March. Simultaneously, the 4th Marines landed on Emirau Island. No Japanese troops were stationed there. The Marines secured Emirau within a week. Rabaul was now encircled. What remained to be determined was how thoroughly Japan's own decisions had already made that encirclement permanent.

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• 7. The Pilots Japan Lost

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  In December 1943, the Japanese Navy transferred hundreds of carrier aircraft from carriers stationed at Truk to bolster Rabaul's air defenses. The decision appeared sound. Those were experienced crews drawn from Japan's most capable carrier formations. Allied planes flying raids on Rabaul shot down 200-300 of them.

  Japan's pilot training program, built around a selective and demanding model, had been unable to keep pace with losses since mid-1942. The attrition suffered through Operation Cartwheel, including over Rabaul, accelerated a trend that was already unsustainable. By early 1944, the Imperial Japanese Navy could not produce trained aircrew quickly enough to replace what it was losing.

  From February 1944 onward, Japan stopped sending fighters or bombers to Rabaul. Land-based Allied aircraft, operating from bases only a few hundred miles away, maintained constant pressure on the base. On the 19th of February 1944, Japan evacuated 120 aircraft to Truk in an effort to preserve what remained of its carrier aviation. Two days later, a Japanese ship attempting to evacuate skilled aircraft mechanics was sunk by Allied bombers.

  The Battle of the Philippine Sea, fought in June 1944, was one direct consequence. The hollowing out of Japan's carrier pilot corps during Operation Cartwheel left Japan's naval aviation unable to compete. Some 70,000 Japanese troops remained at Rabaul, cut off and isolated, until Japan surrendered in August 1945.

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