Central Pacific 7 December 1941-6 December 1943 The Central Pacific Campaign opened abruptly on 7 December 1941, when carrier-based planes of the Japanese imperial Navy launched a surprise attack on Pearl Harbor in Hawaii. At the time it was widely believed that the heart of the U.S. Pacific Fleet had been rendered ineffective since the Japanese aircraft had destroyed or damaged the fleet's eight battleships. As the war unfolded in the Pacific, however, the Navy turned to its aircraft carriers—all of which had been at sea on 7 December—as the capital ships that would carry the war to the enemy. Although the assault on Pearl Harbor was but one of many virtually simultaneous attacks by the Japanese armed forces against the United States and its Allies in the Pacific, it was the one that struck a nerve in the American public and prompted President Franklin D. Roosevelt to demand, and receive, an immediate declaration of war from Congress. To declare war is one thing, but to carry the fight to the enemy is quite another. Almost two years would pass before U.S. Army forces tangled with the Japanese Army in the last weeks of the Central Pacific Campaign. Strategic Setting Most of the Central Pacific Campaign took place in Micronesia, an area of the globe larger than the continental United States, where a multitude of islands lie scattered about a vast expanse of ocean. Clustered into four major groups, these Pacific islands have a landmass of about 1,200 square miles, an area somewhat larger than the state of Rhode Island. The most easterly of the four island groups are the Gilberts, low-lying coral atolls, straddling the equator just west of the international date line. North and west of the Gilberts are the Marshall Islands, a double chain of atolls, reefs, and islets, most of which rise only a few feet above sea level. Stretching almost due west from the Marshalls are the 550 tiny islands of the Caroline group. The Marianas lie just north of the Carolines in a 400-mile north-south chain. Strategically located across the main sea lines of communications between the United States and the Philippines, the islands of Micronesia played a vital role in Japanese war plans. Japan had seized the Carolines, Marshalls, and Marianas (except Guam) from Germany during World War I, retaining control afterward under a mandate from the League of Nations. Its forces had occupied the rest— Guam and the Gilberts—in the course of their initial offensive at the outbreak of war. Once garrisoned, these islands provided Japan an outer perimeter for its expanding empire and put its forces in an excellent strategic position to cut Allied lines of communications. The Central Pacific was equally important to the United States as the path of military advance postulated in the ORANGE plans developed by the Joint Board, composed of planners from the Army General Staff and the General Board of the Navy, during the 1920s and 1930s. According to these plans, in the event of war with Japan the U.S. Pacific Fleet would move from Pearl Harbor to seize selected islands in Micronesia in a methodical advance toward the Philippines, projecting American military and naval strength ever westward. Although few officers truly believed it, the ORANGE plans assumed that the American forces garrisoning the Philippines could hold Manila Bay for up to six months while the Pacific Fleet and its accompanying ground forces conducted an island-by-island advance. By 1938 it was apparent to American planners that the assumptions forming the basis of the ORANGE plans were rapidly becoming invalid. Working in coordination with the British, they concluded that in the event of a global war the United States would probably face Japan alone in the Pacific. While the U.S. Navy took the view that winning the war in the Pacific should be the nation's first priority, Army planners argued that in a war with both Japan and Germany the largely naval war in the Pacific had to remain an economy-of-force, or defensive, theater. The Army view prevailed. When American planners completed the RAINBOW series of plans in June 1939, each plan assumed that in a future war the United States would face a coalition rather than a single enemy military power. In the event, RAINBOW 5 came closest to what actually happened: it envisioned a rapid projection of American forces across the Atlantic to defeat Germany, Italy, or both, and by clear implication relegated the Pacific to a defensive theater. The adoption of a defensive strategy in the Pacific did not necessarily mean inaction. On the contrary, from the earliest days of the Pacific war, American forces struck the Japanese whenever and wherever they could with the meager resources available. As early as April 1942, American planes took the war to the heart of the Japanese Empire with a surprise air attack on Tokyo. Although the daring raid did little more than provide a boost to sagging American morale, it put the government of Japan on notice that the American war effort in the Pacific, even though a secondary priority for the United States in global terms, was still going to be an all-out effort. As the campaign in the Central Pacific got under way, however, at least one well-intentioned early offensive produced some unexpected and, from the U.S. Army's perspective, undesirable results. Continued Central Pacific, Page 2