# Solomon Islands campaign

The Solomon Islands campaign was a major campaign of the Pacific War during World War II. The campaign began with the Japanese seizure of several areas in the British Solomon Islands and Bougainville, in the Territory of New Guinea, during the first six months of 1942. Japanese troops subsequently began the construction of several naval and air bases in the area. Japan's initial goals were to protect the flank of their ongoing offensive in New Guinea, establish a security barrier for the major Japanese base at Rabaul on New Britain, and construct bases from which they could interdict supply lines between the Allied powers of the United States and Australia and New Zealand.
In order to defend their communication and supply lines in the South Pacific, the Allies initiated a counteroffensive in New Guinea and counterattacked Japanese forces in the Solomons via landings on Guadalcanal (see Guadalcanal campaign) and small neighboring islands on 7 August 1942. The ultimate Allied objective was to capture, isolate, or otherwise neutralize the major Japanese base at Rabaul. These Allied offensives initiated a series of land, air and naval engagements with Japan, beginning with the amphibious landings on Guadalcanal. Over the course of the campaign, multiple major battles were fought in the central and northern Solomons, on and around New Georgia Island, and on Bougainville Island.
In a campaign of attrition fought on land, at sea, and in the air, the Allies inflicted heavy losses on Japanese forces. Japan was ultimately unable to replace these losses, particularly in terms of experienced aircrew and pilots. The Allies retook some of the Solomon Islands by force (although Japanese resistance continued until the end of the war), while simultaneously isolating and otherwise neutralizing other Japanese positions, which were then bypassed. The Solomon Islands campaign eventually converged with the New Guinea campaign.

## Background
### Strategic background

On December 7, 1941, after failing to resolve disputes with the United States over the invasion of China and occupation of French Indochina, the Japanese attacked the US Pacific fleet at Pearl Harbor, Hawaii. This surprise attack crippled most of the U.S. Pacific Fleet's battleships instigating a war between the two nations. Attacks on British possessions in the Pacific, beginning with near-simultaneous attacks on British Malaya and Hong Kong, also brought the United Kingdom, Australia, New Zealand and the Dutch East Indies into the conflict. The Japanese sought to neutralize the American and Commonwealth navies, seize territory rich in natural resources, and obtain strategic military bases to defend their newly-gained possessions. According to the Japanese Navy's Combined Fleet Secret Order Number One, dated November 1, 1941, the goals of the initial Japanese campaigns were to "[eject] British and American strength from the Netherlands Indies and the Philippines, [and] to establish a policy of autonomous self-sufficiency and economic independence."
The Empire of Japan accomplished its initial strategic objectives in the first six months of the war, capturing Hong Kong, the Philippines, Thailand, Malaya, Singapore, the Dutch East Indies, Wake Island, New Britain, the northern Gilbert Islands, and Guam. A key Japanese goal was to establish a vast defensive perimeter ranging from British India on the west, through the Dutch East Indies in the south, and on to island bases in the south and central Pacific. The large Japanese army and navy base at Rabaul, which had been captured from the Australians in January 1942, anchored the southern flank of this defensive perimeter. In March and April 1942, Japanese forces occupied and began constructing an airfield at Buka in northern Bougainville, as well as an airfield and naval base at Buin, in southern Bougainville.

### Japanese advance into the Solomons

In April 1942, the Japanese Army and Navy jointly initiated Operation Mo, a offensive to capture Port Moresby in New Guinea. Also part of this plan was an IJN operation to capture Tulagi in the southern Solomons. The objective of the operation was for the Japanese to extend their defensive perimeter to the south, and to establish bases to support possible future advances against Nauru, Ocean Island, New Caledonia, Fiji, and Samoa. Japanese strategists believed these advances would cut the supply lines between Australia and the United States, and effectively eliminate Australia as a threat to Japanese positions in the South Pacific. The Japanese Navy also proposed a future invasion of Australia, which was abandoned when the IJA protested that it currently lacked enough troops to support such an operation.
Japanese troops successfully captured Tulagi, but Japanese attempts to capture Port Moresby were repulsed by American naval forces at the Battle of the Coral Sea. Shortly thereafter, the Japanese Navy established small garrisons on various other northern and central Solomon Islands. One month later, the Japanese Combined Fleet lost four fleet aircraft carriers at the Battle of Midway.
The Allies began countering the continued threat to Australia via a build-up of troops and aircraft in the region, with the eventual goal of reconquering the Philippines. In March 1942 Admiral Ernest King, then Commander-in Chief of the U.S. Fleet, had advocated an offensive from the New Hebrides through the Solomon Islands to the Bismarck Archipelago. Following the American victory at Midway, General Douglas MacArthur, who had taken command of the South West Pacific Area, proposed a lightning offensive to retake Rabaul, which the Japanese were fortifying and utilizing as a major base of operations. The United States Navy advocated a more gradual approach from New Guinea and up the Solomon Island chain. These competing proposals were resolved by Admiral King and U.S. Army Chief of Staff General George C. Marshall, who adopted a three-part offensive strategy. The first priority was the capture of the island of Tulagi in the Solomons. Secondly, Allied forces were to advance along the New Guinea coast. Finally, Allied forces would converge on and capture Rabaul. Orders to capture Tulagi were implemented by a directive of the Joint Chiefs of Staff on 2 July 1942, which named the initial attacks Operation Watchtower. This operation would mark the beginning of the Solomon Islands campaign.

## Course of campaign

On 7 August 1942 U.S. Marines landed on Guadalcanal, beginning the Guadalcanal Campaign, and were subsequently engaged in heavy fighting against Japanese troops. Throughout the months-long battle for Guadalcanal, both sides attempted to reinforce and resupply their forces by sea. The Allies created a cross-service air unit based on Guadalcanal, known as the Cactus Air Force, and eventually established air superiority over the Guadalcanal area during daylight hours. After incurring heavy losses during daylight reinforcement attempts, the Japanese resorted to nightly resupply missions which they called "Rat Transportation" (and the Allies called "the Tokyo Express") through New Georgia Sound (a.k.a. "The Slot"). The Allies fought large naval engagements from August 1942 to February 1943 in an attempt to degrade Japan's ability to resupply its troops on Guadalcanal. So many ships were lost by both sides during these battles that the southern end of New Georgia Sound, the area north of Guadalcanal previously called Savo Sound, became known as "Ironbottom Sound".
The Allies gradually obtained naval and aerial superiority over the Guadalcanal area, finally compelling the Japanese to evacuate their remaining troops from the island in early 1943.
Allied success in the Solomon Islands campaign prevented the Japanese from cutting Australia and New Zealand off from the United States. Operation Cartwheel—the Allied grand strategy for the Solomons and New Guinea campaigns—launched on June 30, 1943, isolated and neutralized Rabaul and destroyed much of Japan's sea and air supremacy. This opened the way for Allied forces to recapture the Philippines and cut off Japan from its crucial resource areas in the Netherlands East Indies.
The Solomons campaign culminated in the often bitter fighting of the Bougainville campaign, which continued until the end of the war.