The nature of the area with its island bases and long lines of water communications made the conflict with Japan essentially a naval war. The advent of the airplane revolutionized the methods of attack but did not alter the basic concepts of strategy or decrease the necessity for controlling the sea. As an island empire, Japan was peculiarly susceptible to any interruption of its water-borne supply system and particularly to any action that would sever the connection with the East Indies whence came indispensable raw materials. The actual conflict may be divided into three phases: the Japanese offensive from 7 December 1941, to 5 June 1942; the offensive-defensive from 7 August 1942, to 19 November 1943, during which Japan had lost the initiative but the A11ies commanded resources only to mount limited operations and the United States offensive from 19 November 1943, to 15 August 1945. Japan’s decision to launch a war was based on the assumption that the conflict in Europe would render Russia and Great Britain negligible factors in the Far East. It was based on the further assumption that the United States, already committed to near belligerency in the Atlantic could not, even if finally successful in that theater, mount an offensive in the Pacific in 1ess than 18 months to 2 years and would not in any case be willing to pay the price of total victory in the Pacific. The Japanese set out to conquer the Philippines, the Dutch East Indies, Malaya, and Burma, which they appropriately called the Southen Resoures Area. Judging that their principal enemy was the United States, the Japanese planned as initial objectives the destruction of a part of the United States Fleet and the acquisition of a line of military bases to reinforce their existing positions in the Marshalls. Attainment of these objectives was to be followed by economic development of the Southern Resources Area and consolidation and strengthening of their newly acquired defensive perimeter in the Central and South Pacific. Japanese carrier forces operating from interior lines and supported by a land-based air force would be able to meet the United States counterattack if, and when, it came. The limited nature of these objectives was apparent in the failure to include - . seizure of the principal United States naval base in the Pacific at Pearl Harbor or damage to the Panama Canal and the ports on the west coast of the United States. The Japanese recognized that control of the air was an essential condition to amphibious operations. The Japanese Fleet was therefore built around a striking force of 6 carriers to be drawn from a total of 10 available and 7 more under construction or being converted from merchant hulls. With a high degree of tactical success this force struck Pearl Harbor on 7 December 1941, employing 360 of 414 embarked aircraft. Half the attacking force was directed against airfields in the Hawaiian Islands; half against fleet units in Pearl Harbor. Nineteen warships were hit among which were 5 battleships that came to rest on the bottom. The Japanese then proceeded to the conquest of the Southern Resources Area which they com - pleted in an incredibly short time. The comnined aircraft strength of the Japanese Army and Navy, carrier- and shore-based, was approximatey 2,625 units. These were opposed by approximately half that number of land-based aircraft widely dispersed among the various United States and Allied bases in the Far East. At the points of conflict the Japanese achieved by virtue of the mobility inherent in a properly emplloyed carrier force a numerical superiority of at least 4 to 1. To this factor must be added the intangible value of surprise, superb training, and combat experience. With the exception of three destroyers sunk by Allied submarines, not one Japanese major combat vessel was lost and very few were damaged. Their air, ground, and shipping losses were equally insignificant, while the United States, Great Britain, the Netherlands, and Australia lost the majority of sea, land, and air forces engaged. April 1942 found the Japanese with their empire greatly enlarged, their fleet intact, and morale at a high level. Between 7 December 1941 and 9 Apri11942, the Japanese carrier striking force had operated across a third of the earth’s circumference, from Hawaii to Ceylon, and conducted strikes against ships and shore installations at Pearl Harbor, Rabaul, Ambon, Darwin, Tjilatja, Colombo, and Trincomalee. Allied losses to Japanese carrier air included five battleships, one aircraft carrier, one cruiser, and seven destroyers sunk or very heavily damaged; three battleships, three cruisers, and one destroyer damaged and thousands of tons of auxiliaries and merchant ships sunk. Hundreds of Allied aircraft, as well as docks, hangarsa and base facilities, were destroyed or captured. The enemy force was seldom sighted and never effectively attacked. Control of the Western Pacific and its island and coastal perimeter lay in Japanese hands until such time as forces to challenge them could be contructed and assembled. The Japanese had not, however, brought to action the carrier forces of the United States Pacific Fleet, which remained the sole immediate threat capable of striking through their newly acquired defensive perimeter and of turning further amphibious advance into defeat. Encouraged by the ease with which they achieved their initial objectives in the first five months of the war and perhaps influenced by the carrier-launched Dolittle raid, the Japanese undertook the extension of their original defensive perimeter. At the cost of delaying the development of their newly acquired bases, they determined to cut the lines of communication between the United States and Australia by seizing Port Moresby, the last important Allied foothold in New Guinea, New Caledonia, the Fijis, and Samoa, and to improve the defensive perimeter on the east and north by the capture of Midway and the western A1eutians. The Japanese then embarked on a threepronged offensive. The first avance was directed against Port Moresby. In early May 1942, an amphibitous force supported by three carrers, steamed south into the Coral Sea. A United States task force including the carriers Lexington and Yorktown discovered the transports on 7 May and sank the light carrier Shoho by air attack. Throughout the rest of the day both Japanese and United States carrier forces searched unsuccessfully for each other. Early the next morning contact was made and simultaneous air attacks launched. A Japanese carrier, the Shokaku, received severe damage from hits by dive bombers. The Yorktown took light damage; the Lexington with uncontrollable gasoline fires was abandoned and sunk by United States destroyers. With their control of the air at the objective in serious doubt, the Japanese retired. The engagement, the first of four carrier duels to take place during the next 6 months, was tactically indecisive but of considerable strategic consequence. Japanese occupation of Port Moresby by sea was defered to July and finally abandoned following the Battte of Midway. The Japanese Army thereafter attempted the conquest of Port Moresby over the Owen Stanley Mountains without air support. The result was the disaster at Buna. 22 Aware of the fact that available United States carrier strength had been in or enroute to the South Pacific as late as 8 May, the Japanese designated 6 June aS the date for the occupation of Midway to be preceded by a diversionary carrier strike on Dutch Habor in the Aleutians. Against Midway- was sent a transport force covered by the main strength of the Japanese Fleet including four carriers. A group of two carriers and escorts was assigned the task of raiding Dutch Habor; this attack was to be followed by the occupation of Adak, Kiska, and Attu in the Aleutian chain. On 3 June naval patrol planes made initial contact with the southern transport force steaming east toward Midway, and early on 4 June the main body of the Japanese Fleet was discovered. Concentrating on the destruction of the Midway air group, composed of Marine and Army aircraft and naval patrol planes, and diverted by torpedo-plane attack, the Japanese carriers were’ taken by surprise and fell before the dive bombers of a hastily assembled American carrier task force composed of the Enterprise, Hornet, and Yorktown. Three Japanese carriers were sunk. A fourth, seriously crippled, was finally destroyed by the Japanese theselves. In a counterattack the Yorktown was heavily damaged by aerial torpedoes and the following day sunk by- an enemy submarine. As at Coral Sea, with control of the air irretrievably lost, the Midway invasion force turned back. The Japanese, nevertheless, landed on Kiska and Attu on 6 and 7 June but canceled the occupation of Adak. Two important naval actions had been fought without the forces themselves engaging in opposing surface gunfire. Aviation had demonstrated its latent power as the principal offensive element of the new American Navy. The loss of four of their finest aircraft carriers weakened the powerful striking force with which the Japanese had achieved their conquests. Battleships and seaplane tenders were withdrawn from the fleet for hasty conversion to carriers, but the Japanese Navy never regained the position it lost at Midway. The initiative had shifted to the United States