In the six months between August 1942 and February 1943, the United States and its Pacific Allies fought a brutally hard air-sea-land campaign against the Japanese for possession of the previously-obscure island of Guadalcanal. The Allies' first major offensive action of the Pacific War, the contest began as a risky enterprise since Japan still maintained a significant naval superiority in the Pacific ocean.

Nevertheless, the U.S. First Marine Division landed on 7 August 1942 to seize a nearly-complete airfield at Guadalcanal's Lunga Point and an anchorage at nearby Tulagi, bounding a picturesque body of water that would soon be named "Iron Bottom Sound". Action ashore went well, and Japan's initial aerial response was costly and unproductive. However, only two days after the landings, the U.S. and Australian navies were handed a serious defeat in the Battle of Savo Island.

A lengthy struggle followed, with its focus the Lunga Point airfield, renamed Henderson Field. Though regularly bombed and shelled by the enemy, Henderson Field's planes were still able to fly, ensuring that Japanese efforts to build and maintain ground forces on Guadalcanal were prohibitively expensive. Ashore, there was hard fighting in a miserable climate, with U.S. Marines and Soldiers, aided by local people and a few colonial authorities, demonstrating the fatal weaknesses of Japanese ground combat doctrine when confronted by determined and well-trained opponents who possessed superior firepower.

At sea, the campaign featured two major battles between aircraft carriers that were more costly to the Americans than to the Japanese, and many submarine and air-sea actions that gave the Allies an advantage. Inside and just outside Iron Bottom Sound, five significant surface battles and several skirmishes convincingly proved just how superior Japan's navy then was in night gunfire and torpedo combat. With all this, the campaign's outcome was very much in doubt for nearly four months and was not certain until the Japanese completed a stealthy evacuation of their surviving ground troops in the early hours of 8 February 1943.

Guadalcanal was expensive for both sides, though much more so for Japan's soldiers than for U.S. ground forces. The opponents suffered high losses in aircraft and ships, but those of the United States were soon replaced, while those of Japan were not. Strategically, this campaign built a strong foundation on the footing laid a few months earlier in the Battle of Midway, which had brought Japan's Pacific offensive to an abrupt halt. At Guadalcanal, the Japanese were harshly shoved into a long and costly retreat, one that continued virtually unchecked until their August 1945 capitulation.