Launching the Central Pacific Offensive
Early Plans for a War with Japan
Between November 1943 and August of the following year, American forces captured a series of key outposts in the Gilbert, Marshall, and Mariana Islands. Under the direction of Admiral Chester W. Nimitz, amphibious forces advanced almost 2,000 nautical miles, thrusting from Tarawa on the outer fringe of the enemy's defenses to within aerial striking distance of the Japanese homeland. Although this Central Pacific campaign saw the introduction of many new weapons, the strategy of attacking directly westward against Japan had for several decades been under study by American war planners. (See Map I, Map Section.)
THE EVOLUTION OF ORANGE PLAN
American acquisition from Spain of Guam and the Philippine Islands was followed within a few years by the emergence of Japan as a world power. The question arose whether the Philippines, at the end of a long and vulnerable line of communications, could be defended against the modern armed forces of Japan. Since both the American Army and Navy would take part in defending these islands, the Joint Board, an agency created to develop plans and policies which would most effectively use the available forces of both services, turned its attention to developing a coordinated plan for a possible war in the Pacific. Defending the Philippines, however, seemed so difficult a task that President Theodore Roosevelt, writing in 1907, termed the islands "our heel of Achilles."1
War plans of this era derived their titles from the code name of the probable enemy, and because Japan was designated ORANGE, the plan dealing with a conflict in the Far East was called ORANGE Plan. The earliest drafts required the Army to defend the Philippines until the fleet could shepherd reinforcements across the Pacific. Planners believed that the Japanese Navy would challenge the approach of the American armada and that the ensuing battle would decide not only the fate of the Philippines but the outcome of the war.
Naval strategists realized that before a relief expedition could be dispatched to the Far East, Japan certainly would have seized Guam, thus depriving the United States of its only fleet anchorage between Pearl Harbor and Manila Bay. Either Guam would have to be retaken or some other site occupied as a coaling and repair station. Whichever course of action was adopted, a landing force made up from the various ships' crews could not be used. With Japanese battleships lurking just over the horizon,
the Philippine relief expedition could not afford to have any large number of Bluejackets and Marines serving ashore and absent from their battle stations.2
Since the recapture of Guam or the taking of some other island--Truk was most frequently designated the prime objective3--was an integral part of the war at sea, such missions fell to the naval services and specifically to the Marine Corps, which was especially suited to those operations, During the Spanish-American War, a Marine battalion had landed at Guantanamo Bay to obtain a coaling station for the American ships blockading Cuba. Following the war, Marine units inherited the mission of occupying and defending advanced naval bases, and some naval officers began to urge that specially equipped defense forces be incorporated into each American squadron. Various planners cooperated in applying the lessons learned at Guantanamo Bay to the situation in the Pacific.
Among the first Marines to claim for their Corps an important role in an ORANGE war were Major Dion Williams and Captain Earl H. Ellis. Writing in 1912, Williams offered tables of organization for a brigade to accompany the battle fleet and assist it by occupying poorly defended anchorages, emplacing weapons, and guarding against counterattack.4 Ellis, whose study appeared a few years later, agreed with the basic theory set forth by Williams, but he prophesied that the day might come when the enemy had fortified those islands suitable as advanced bases. Should this happen, the Marine contingent would be called upon to seize a defended beach. The capture of the objective rather than its subsequent defense would become the primary task of the Marines supporting the battle fleet.5
As a result of World War I, during which Japan and the United States had been allies, America's potential enemy gained control over the former German possessions in the Marshalls, Carolines, and Marianas. The Philippines were more vulnerable than before and Guam now was ringed by Japanese outposts. By 1921, the Marine Corps had evaluated recent gains by Japan and developed a realistic framework for its own operational and logistical planning. Staff officers believed that Guam and probably the Philippines would fall to the enemy shortly after the outbreak of war, and that Marine Corps units, in cooperation with Army troops, would face the task of seizing bases in the Marshalls, Carolines, Marianas, and Philippines. In addition, they assumed
that the Marine Corps was to take part in the final advance from the Philippines to Japan itself.6
Earl Ellis, now a major, concentrated on one segment of a war against ORANGE and devised Operation Plan 712, which dealt with the systematic reduction of the Marshall Islands. He also outlined the tactics to be used against such objectives as Eniwetok, Wotje, and Maloelap. Although his theories were limited by the equipment then available, he made several sound recommendations, urging among other things that troops fighting ashore have at their disposal the on-call fire of supporting warships. Yet, the amphibious assault depicted by Ellis was understandably crude in comparison to the skilfully coordinated landings of World War II.7
Whatever the flaws in his theory, Ellis's plan marked a complete break with tradition. No longer would Marines be used primarily to defend advanced bases. Instead, they would seize these bases from the enemy.
During the 1920s and 1930s, various Marine Corps officers elaborated upon Ellis' amphibious doctrine. Key Pacific islands were studied as potential battlefields, new types of landing craft were tested, and more efficient landing techniques came into use. Thus did the Marine Corps devote its energies to preparing for whatever amphibious missions might be assigned it in an ORANGE war.8
Framing the broad strategy for a possible war in the Pacific remained the task of the Joint Army and Navy Board. The ORANGE Plan, actually a preferred course of action rather than a detailed war plan, needed little revision, and the missions first assigned the services before World War I remained much the same as World War II approached. The Army was to deny Manila Bay to the enemy for as long a time as possible, while the Navy, capturing en route as many bases as it might need, steamed westward to defeat the Japanese fleet and break the siege of the Philippines. Although some planners doubted that the Philippine garrison could hold out until help arrived, and in fact believed that the islands were indefensible, the basic concept persisted throughout the 1930s.9 Finally, on the eve of war with the Axis powers, ORANGE Plan, which had presumed that Japan would
be the only enemy, was incorporated into an overall strategy designed to meet the needs of a two-ocean conflict.
STRATEGY FOR A GLOBAL WAR
As early as 1937, the United States Navy had sent a representative to Great Britain to discuss the employment of the American fleet in the event that these two nations should go to war with Japan. During the conversations, the possibility that Japan might join forces with Italy and Germany was explored. The British Admiralty was satisfied that, in the event of another world war, the United States Navy should concentrate in the Pacific, leaving the effort in the Atlantic to Great Britain and her continental allies.10 By June 1939, American planners were fully aware that Japan, possibly without the aid of Germany and Italy, might take advantage of the European crisis to seize British, French, or even American holdings in the Orient. Because the potential enemies might either act independently or combine their efforts, the Joint Board in June 1939 ordered that five new war plans be written, the RAINBOW series, each of which might incorporate the features of several "color" plans such as ORANGE. These new plans were designed to meet danger from various sources. Two of them dealt with the defense of the western hemisphere, two others with a war in the Pacific, and still another, RAINBOW 5, with a war in Europe or Africa that pitted the United States, France, and Great Britain against Germany and Italy.
Although a greatly expanded RAINBOW 5 eventually became the basis of America's World War II strategy, work on this particular plan got off to a discouraging start, for France suddenly collapsed, and the Axis nations signed a formal military alliance. A two-ocean war now seemed probable, a conflict in which winning the battle of the Atlantic would be of more consequence than a victory in the Pacific. In the words of Admiral Harold R. Stark, the Chief of Naval Operations, "if Britain wins decisively against Germany we could win everywhere; but . . . if she loses the problem confronting us would be very great; and, while we might not lose everywhere, we might, possibly, not win anywhere."11 During January 1941, President Franklin D. Roosevelt announced a policy that emphasized the greatest possible aid to Britain, and a series of Anglo-American conferences began that same month which saw the two nations agree upon defeating Germany and Italy before turning their full might against Japan.12
Since the United States was now committed to assuming a strategic defensive on the outbreak of war in the Pacific, joint planners began rewriting RAINBOW 5 to include the probability that Japan would cooperate with her Axis partners in any future conflict.
Essentially, this revision consisted in delaying indefinitely the Central Pacific campaign advocated by the ORANGE Plans. Instead of seeking immediately a decisive sea battle in Philippine waters, the Navy would be restricted in its early operations to attacks upon the Marshalls designed to prevent the enemy from concentrating his forces against Singapore. In brief, the naval offensive against Japan, to which the Navy and Marine Corps had devoted so much thought, became but a single element in a global strategy designed primarily to crush Germany and Italy as rapidly as possible.13
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 Henry F. Pringle, Theodore Roosevelt: A Biography (New York: Harcourt and Brace, 1931) , p. 408.
 Capt William R. Shoemaker, USN, "Strategy of the Pacific: An Exposition of the ORANGE War Plan," dtd Aug14; Admin and StratSecs, ORANGE Plan, dtd Mar16 (NA folder no. 40, OP 29 folder no. 5, OAB, NHD).
 RAdm Charles J. Moore cmts on draft MS and interview by HistBr, G-3, dtd 26Nov62, hereafter Moore comments (Gilberts Comment File, HistBr, HQMC). Admiral Moore, who served as Admiral Spruance's chief of staff, noted: "This Truk operation became an obsession of the Navy and Marine Corps and was not eliminated as an objective until the raid on Truk on 17 February 1944."
 Maj Dion Williams, "The Naval Advanced Base," dtd 26Ju112 (NA folder no. 29, OP 29 folder no. 6, OAB, NHD) .
 Capt Earl H. Ellis, "The Security of Advanced Bases and Advanced Base Operations," ca. 1913 (IntelSec, DivOps and Trng Files, HistBr, HQMC).
 MarCorps War Plan against ORANGE, Resume, 1921 (War Plans File, HistBr, HQMC).
 Maj Earl H. Ellis, OPlan 712, 1921 (War Plans File, HistBr, HQMC).
 For the story of the Marine Corps role in the development of amphibious doctrine and equipment, see LtCol Frank O. Hough, Maj Verle E. Ludwig, and Henry I. Shaw, Jr., Pearl Harbor to Guadalcanal--History of U. S. Marine Corps Operations in World War II, v. I (Washington: HistBr, G-3, HQMC, 1958), pp. 8-34, hereafter Hough, Ludwig, and Shaw, Pearl Harbor to Guadalcanal.
 Development of Joint Army-Navy War Plan ORANGE (RG 115, WPD 2720-22,WWII RecsDiv, FRC, Alexandria, Va.) ; Louis Morton, "Strategy and Command: Turning the Tide, 1941-1943--The War in the Pacific--U. S. Army in World War II," MS in OCMH, pt II, pp, 24-31, 38-41, hereafter Morton MS. See Louis Morton, The Fall of the Philippines--The War in the Pacific--U. S. Army in World War II (Washington: OCMH, DA, 1953), passim, for a discussion of the strong body of Army opinion which held that the islands could not be successfully defended with the forces available.
 Morton MS, Pt, III, p. 2.
 Maurice Matloff and Edwin M. Snell, Strategic Planning for Coalition Warfare; 1941-1942--The War Department--The U. S. Army in World War II (Washington: OCMH, DA, 1953), p. 25.
 Morton MS, pt. III, pp. 34 & 35, 37; Louis Morton, "American and Allied Strategy in the Far East," Military Review, v. 29, no. 9 (Dec49), p. 33, hereafter Morton, "Strategy."
 Morton, "Strategy," pp. 37-38.