Pacific Theater: Overview

World War II in the Pacific covered a vast sweep of ocean and land, involving millions of soldiers in years of epic conflict. This page gives an overview of the immense undertaking.

Captain John R. Campbell, Quartermaster Corps, left, and First Sergeant Richard Estes, right, giving technical advice to mechanics, New Guinea, March 1943
Captain John R. Campbell, Quartermaster Corps, left, and First Sergeant Richard Estes, right, giving technical advice to mechanics, New Guinea, March 1943.

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WW II Pacific Theater of Operations Overview

WW II Pacific Theater of Operations, Overview Map
World War II, Pacific Theater of Operations, Overview Map. Click fon map or larger image.

In late 1941 the Japanese completed secret plans for a huge assault against Malaya, the Philippines, and the Netherlands East Indies, to be coordinated with a crushing blow on the U.S. Pacific Fleet at Pearl Harbor, Hawaii. Following their plan, in the first seven months after Pearl Harbor, into mid-1942, the Japanese gained control over a huge area of the Pacific basin extending from Burma to the Gilbert Islands and from the Aleutians to the Solomons. With this expansion, the Japanese were somewhat overextended and sought to press their advantage before the Allies could develop enough air and sea forces to counterattack.

In December 1941, Pearl Harbor was attacked (7 December) and Wake Island was taken (23 December). On 23 January 1942, the Japanese invaded the island of New Britian, overwhelmed the Australian-held Rabaul fortress, then expanded their hold on New Britain and moved into northeastern New Guinea. Rabaul's heavily fortified harbor at the northern tip of New Britain became the main refueling and refitting facility for the Japanese in the southwestern Pacific. On 11 March 1942, Gen. Douglas MacArthur reluctantly left the Philippines and relocated his headquarters in Australia. A May 1942 Japanese offensive moved to Tulagi from the northern Solomons, then to Guadalcanal. Using a newly constructed airstrip at Lunga Point on Guadalcanal, they hoped to interdict Allied connections to Australia by seizing New Caledonia, the Fijis, and Samoa. By May of 1942 the Japanese prepared to further expand in the South Pacific and to attack against the weakly defended Allied line of communications between the U.S. outpost in Hawaii and Australia.

Japanese Plans in the Pacific Disrupted

The Allies understood the Japanese intentions and made effective countermoves. They repulsed Japanese attempts to take Port Moresby (the last Australian base in the area) in southeastern New Guinea by sea in May 1942 in the Battle of the Coral Sea, and again in August by the Australians at Milne Bay. Following the Battle of Midway 4-7 June 1942, the Allies launched a limited offensive to protect their line of communications and to prevent the Japanese from consolidating their gains. On 2 July 1942 the U.S. Joint Chiefs of Staff issued orders specifying that Rabaul would be the focus of the counteroffensive, mounted in three stages:

  • First, the seizure of bases in the southern Solomons
  • Second, the reoccupation of the remainder of the Solomons and part of the north coast of New Guinea
  • Third, the recapture of Rabaul itself and the rest of the Bismarck Archipelago

Success of this plan would position the Allies for further advances to drive the Japanese out of the Philippines and to attack Japan's home islands.

Recapture of Rabaul, Stage 1: Guadalcanal

On 7 August 1942 the first stage of the offensive began with landings by a Marine division on Guadalcanal and nearby islands in the Solomons. The Japanese reacted vigorously and the battle raged until the island was finally secured in February 1943, firmly establishing the Allies in the Solomons.

In New Guinea, the Japanese pushed a drive toward their objective over the Owen Stanley Mountains from the Buna-Gona area in the southeast coming within 30 miles of Port Moresby by mid-September. MacArthur committed additional Australian troops who pushed the invaders back across the mountains by mid-November. By January 1943 the Japanese were off the Papua peninsula, the eastern end of New Guinea, and MacArthur continued to push west along the northern shore.

Following the Papua (New Guinea) and Guadalcanal campaigns the Allies prepared ground forces for the second phase of the drive on Rabaul, while the Japanese made a major effort to reinforce their positions in the Solomons and New Guinea. In the Battle of the Bismarck Sea (1-3 March 1943) Papua based planes attacked and destroyed a Japanese convoy of 12 ships (including 8 transports), some 3,000 men, and 20 to 30 planes. Allied losses in the three-day running battle were 5 planes.

In April, and again in June 1943, Japanese carrier and Rabaul-based planes tried but failed to knock out Allied air and naval power in the Solomons and New Guinea. The loss of carrier planes and pilots during this air offensive further reduced the capabilities of the Japanese Combined Fleet whose commander, Admiral Isoroku Yamamoto, was himself shot down and killed over Bougainville.

Recapture of Rabaul, Stage 2: Solomons and New Guinea

Stage Two of the offensive against Rabaul began in late June 1943, to reoccupy the remainder of the Solomons and much of the northern coast of New Guinea. MacArthur's Sixth Army troops landed in New Guinea and made contact with the Australian division already fighting there. Concurrently, Admiral Halsey's South Pacific forces, operating under MacArthur's strategic direction, landed on the island of New Georgia in the Central Solomons to secure air bases to support further advances in a two-pronged drive up the Solomons and the New Guinea coast toward Rabaul. Halsey's advance in the Solomons started from Guadalcanal and moved toward the Japanese air base at Munda on New Georgia Island about 200 miles north, starting with Marines and Army landings 10 June 1943 and ending with the fall of Munda on 5 August 1943 after six weeks of hard fighting. It was October before the Allies had fully secured the island group, moving from island to island defeating the Japanese defenders.

The next major operation was an invasion of the island of Bougainville, beginning with nearby islands on 25-27 October 1943. A Marine division landed on the west coast of Bougainville at Empress Augusta Bay on 1 November 1943. The Marines were followed within the month by an Army division and replaced in the next month by another Army division. By Christmas the Empress Augusta Bay beachhead was secure, all that was needed on the island since Japanese airfields and the Japanese garrison on Bougainville were neutralized by bombardment and their supply lines were cut. Nonetheless, the Japanese continued to fight and managed strong counterattacks as late as March 1944.

The Bougainville campaign isolated the Japanese forces left in the Solomons and further crippled the Japanese Combined Fleet as the U.S. Navy gained superiority of naval power in the Central Pacific.

During the time of the campaign in the northern Solomons, Southwest Pacific American and Australian troops pushed forward on the other prong of the offensive moving to take the Huon Peninsula of Papua New Guinea (2 October 1943), fighting more than three months, until mid-February 1944, to secure the objective. Forces of both the South and Southwest Pacific were now in position for a final assault on Rabaul.

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Recommended Books about the Pacific Theater of Operations