The Guadalcanal Campaign, also known as the Battle of Guadalcanal and codenamed Operation Watchtower by Allied forces, was a military campaign fought between 7 August 1942 and 9 February 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.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 peak 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.