August 1942: Battle of Guadalcanal

The Battle of Guadalcanal, fought in and around the Solomon Islands between 7 August 1942 and 8 February 1943, was the first Allied land campaign in the Pacific Theater. Allied victory in Guadalcanal marks the beginning of the ‘island hopping’ or ‘leapfrogging’ campaign in the Pacific, by which Allied forces captured Japanese-held islands one-by-one to gradually expand the range of air and naval operations, eventually reaching the Home Islands.

In their rapid invasion of Southeast Asia and Oceania following the attack on Pearl Harbor, the Japanese had seized control of the Solomon Islands and were, in August 1942, constructing an air base on Guadalcanal. The Japanese intended to use this air base to attack shipping between the USA and Australia, thus isolating Australia and forcing its surrender. The USA recognized the threat this air base posed to Australia and invaded Guadalcanal in an attempt to prevent the Japanese from completing this air base.

Fighting on Guadalcanal and the rest of the Solomon Islands was costly in both casualties and the loss of military equipment, with both Japan and the Allies experiencing major losses. Although some of these losses were the result of naval combat and fierce jungle fighting, the majority of casualties were a result of disease or infection due to the tropical climate; only a quarter of casualties during the Battle of Guadalcanal were the result of combat. The high rate of losses favored the Allies because, unlike Japan, the USA was able to swiftly and easily replace manpower and equipment. The losses that Japan suffered during the Battle of Guadalcanal not only could not be replaced during the fighting there, but also could not be replaced before the end of the war. The losses suffered by Japan during the Battle of Guadalcanal and other engagements in the Pacific drained its manpower and resources and forced Japan to conduct only defensive operations in the Pacific Theater for the remainder of the war.

The Allied capture of Guadalcanal was the first of the ‘island hopping’ campaigns that brought the USA closer to its strategic objectives of the Philippines and the Japanese Home Islands. The range of naval vessels and aircraft was limited during the Second World War, meaning that the capture of long-distance objectives usually required the capture of air and naval bases closer to the starting location first. In addition to this logistical necessity, Allied forces in the Pacific Theater also pursued ‘leapfrogging’, by which only strategic islands were invaded and large concentrations of Japanese troops elsewhere were ignored. These strategies defined combat in the Pacific Theater, as Allied forces pursued Japan through the Solomon Islands and the Bismarck Archipelago to the Philippines, and through the Gilbert and Marshall Islands, the Caroline Islands, the Mariana Islands, and the Iwo Islands to the Japanese Home Islands.

Allied victory in the Battle of Guadalcanal convinced Roosevelt to abandon his strict adherence to a ‘Europe First’ policy and approve further offensive operations against Japan simultaneous with Allied operations in Europe. Prior to the Battle of Guadalcanal, Roosevelt believed that the USA only had the resources to conduct offensive operations in one theater at a time and, in deference to the needs of Britain and the USSR, the USA would prioritize Europe. Exceptions were only made to prevent major strategic defeats, such as the disruption of supply lines to Australia. Allied victory at Guadalcanal convinced Roosevelt that American forces could fight simultaneously in both theaters. The approval of Allied offensives in the Pacific Theater shortened the war by years and meant that Japan’s defeat followed Germany’s defeat by months rather than years.