The Guadalcanal Campaign, also known as the Battle of Guadalcanal and codenamed Operation Watchtower by Allied forces, was a military campaign fought between August 7, 1942 and February 9, 1943 on and around the island of Guadalcanal in the Pacific theatre of World War II. It was the first major offensive by Allied forces against the Empire of Japan.
On August 7, 1942, Allied forces, predominantly American, landed on the islands of Guadalcanal, Tulagi, and Florida in the southern Solomon Islands with the objective of denying their use by the Japanese to threaten the supply and communication routes between the U.S., Australia, and New Zealand. The Allies also intended to use Guadalcanal and Tulagi as bases to support a campaign to eventually capture or neutralize the major Japanese base at Rabaul on New Britain. The Allies overwhelmed the outnumbered Japanese defenders, who had occupied the islands since May 1942, and captured Tulagi and Florida, as well as an airfield (later named Henderson Field) that was under construction on Guadalcanal. Powerful U.S. naval forces supported the landings.
Surprised by the Allied offensive, the Japanese made several attempts between August and November 1942 to retake Henderson Field. Three major land battles, seven large naval battles (five nighttime surface actions and two carrier battles), and continual, almost daily aerial battles culminated in the decisive Naval Battle of Guadalcanal in early November 1942, in which the last Japanese attempt to bombard Henderson Field from the sea and land with enough troops to retake it was defeated. In December 1942, the Japanese abandoned further efforts to retake Guadalcanal and evacuated their remaining forces by February 7, 1943 in the face of an offensive by the U.S. Army's XIV Corps, conceding the island to the Allies.
The Guadalcanal campaign was a significant strategic combined arms victory by Allied forces over the Japanese in the Pacific theatre. The Japanese had reached the high-water mark of their conquests in the Pacific, and Guadalcanal marked the transition by the Allies from defensive operations to the strategic offensive in that theatre and the beginning of offensive operations, including the Solomon Islands, New Guinea, and Central Pacific campaigns, that resulted in Japan's eventual surrender and the end of World War II.