The Pacific War Online Encyclopedia
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The Pacific War (Japanese: Dai Tō-A Sensō, "Greater East Asia War") was fought between the Japanese Empire and the United States and their allies from 7 December 1941 to 15 August 1945. The war began with the surprise attack on Pearl Harbor and simultaneous landings in Malaya, though its origins can be traced back much earlier. The war ended with the nuclear attacks on Hiroshima and Nagasaki and the Russian offensive in Manchuria, which, together with the submarine blockade, finally forced the Japanese to surrender.
Origins. Tensions between Japan and the United States went back at least to the Russo-Japanese War of 1905, when Japan astonished the world by soundly defeating Russia on both the land and the sea. President Theodore Roosevelt, who was an admirer of the Japanese, offered his good offices to both warring parties, and the Treaty of Portsmouth ended the war on terms that were generally favorable to Japan. However, certain factions in Japan were dissatisfied with the peace terms. Combined with racist incidents against Japanese immigrants on the U.S. West Coast and laws prohibiting further Japanese immigration, this dissatisfaction created a rift between what had previously been friendly nations.
Naval Conference gave
Japan just three battleships
for every five
and American battleships. Many officers in the
considered this an affront to the Emperor
honor of Japan. The Great
hit Japanese agriculture and light
industry particularly hard, and the prospect of further expansion
the Asian mainland
became increasingly attractive to Army leaders. Kwantung
Army officers staged
an incident on the South Manchuria Railway on 18 September 1931 as
seize control of all Manchuria.
In 1933, following a League of Nations
report criticizing the
takeover, Japan walked out of the League of Nations and, in
1935, announced it would not renew the naval disarmament treaties,
to expire in December 1936.
and the West Slide Towards War. Japan's
Manchuria, and the war with China
that began in 1937, deepened the rift between the U.S. and Japan.
October 1937, in response to the crisis at Shanghai,
Roosevelt gave his
"Quarantine Speech" at Chicago.
On 11 November 1938
administration imposed a "moral embargo" against Japan, and by
1939, Gallup polls showed that 72 percent
of Americans favored an embargo on war materials shipped to Japan.
The fall of France
and Holland in the spring of
1940 radically changed the picture in the Far East. The Western
were no longer in a position to adequately protect their colonies,
the Netherlands East
Indies in perhaps the weakest position of all.
Japanese Foreign Minister Arita's declaration on 15 April 1940
that Japan had a special interest in seeing that oil
continued to flow
from the NEI was seen as laying the diplomatic
groundwork for Japan to
take possession of the Dutch colony. These developments finally
prompted the United
States to embargo sales of certain grades of scrap iron
and aviation gasoline to
Japan, on 22 July 1940.
Japan responded to events in Europe by occupying northern French Indochina and joining the Tripartite Pact in September 1940. The combination of events was probably coincidental but appeared highly provocative. The United States responded by extending the embargo to include all scrap iron. The accession of Japan to the Axis is widely viewed as a critical development, but the United States had already come to view Japan as a co-conspirator with the "bandit" nations of Germany and Italy and there was little immediate change in U.S. policy.
to war was set on 2 July 1941, at a
Conference in the Imperial Presence. The conference decided on a
southward expansion or "Southward Ho!" (Prange 1988) while keeping
Japan's options open in case of a Russian collapse. Matters came
head when Japan occupied
French Indochina on 21 July 1941. The United States,
and the Netherlands
responded with a complete oil
By August 1941 the Japanese were withdrawing all their merchant shipping into the sea lanes immediately around Japan, a fact that U.S. Navy intelligence was quick to pick up.
the last months of 1941, Nomura
engaged in fruitless negotiations with the U.S. Secretary of
State, Cordell Hull. Though the two men respected each other and
sought to avoid a war, their positions were irreconcilable. The
Japan out of
China. Japan wanted a free hand on the continent.
The Japanese government continued to
because the Emperor insisted on it, and because the Japanese
risky war with the United States would be. The United States
negotiate because they did not want preparations for possible
European war to be disrupted by a Pacific war, and because it was
time was on the side of the United States, which were rapidly
sending reinforcements to the Philippines.
By 4 September 1941 the Japanese position had hardened into a demand that the United States and Britain give Japan a free hand to settle the China Incident, in return for which Japan promised not to use French Indochina as a base for operations against the Western powers and to withdraw troops from China and French Indochina once the China Incident was settled to her satisfaction. These terms could not be reconciled with the American position, which had hardened into a demand Japan pull out of China immediately and completely.
December 1941 - March 1942: The Centrifugal Offensive. On 7 December 1941 (Hawaii time) the Japanese struck, launching a devastating surprise attack on Pearl Harbor to prevent the Americans from interfering with the capture of the resource-rich Western colonial possessions in Southeast Asia (the Nampū Yōiki or "Southern Important Territories"). Once these were secured, the Japanese planned to establish an impenetrable defensive perimeter to ward off any Allied counteroffensive, then seek a negotiated settlement on favorable terms.
The Japanese planned to advance simultaneously on two fronts. The first was directed primarily against Malaya, Sumatra and western Java, but also seized important points along the west coast of Borneo. The second front began at the Philippines and advanced through Makassar Strait to eastern Java. The western flank was covered by occupying Thailand while the eastern flank was protected by seizing strategic points in the eastern Netherlands East Indies, particularly in the lesser Sunda Islands and western New Guinea. The remainder of the Japanese defensive perimeter in the Pacific was extended by seizing Rabaul, the Gilbert Islands, Wake, and Guam.
The Centrifugal Offensive came to a successful conclusion with the surrender of Java on 8 March 1942. The Japanese achieved all their initial war objectives ahead of schedule and with astonishingly slight losses. Instead of the 20% to 30% naval losses anticipated in prewar planning, the Japanese had lost only 23 warships of destroyer size or smaller (for a total of 26,441 displacement tons) and 67 transports and cargo ships totaling 314,805 tons, along with a few hundred aircraft and a few thousand personnel. This astonishing success was misread by Japanese planners, who failed to recognize that the Allies would learn from bitter experience and that American mobilization was certain to eliminate Japan's military superiority. Rather than consolidate their conquests and build their defense perimeter, as originally planned, the Japanese began looking for new worlds to conquer. Postwar, Hara characterized this unrealistic attitude as "Victory Disease", and there is wide consensus among historians that this attitude led to the Japanese setback at Coral Sea and the disaster at Midway.
April 1942 - June 1942: The Second Operational
Second Phase was largely the strategy of the Japanese Navy,
since the Army was uninterested in new large-scale operations when
was already heavily committed in China
and inclined to prepare for war with Russia.
The Japanese objective was
to isolate Australia, forcing it
out of the war, and to seize Hawaii
as a forward base. Alaska would
then be ripe for the picking, and some Japanese leaders even
the seizure of portions of Australia and the states of Washington
Oregon. The Pacific would be transformed into a Japanese lake.
The Japanese planned a series of advances along two axes that in many respects resembled the Allied counteroffensive of 1943-1944, but in reverse. The first blow would fall on Port Moresby and Tulagi in early May 1942, projecting Japanese power over the Coral Sea and opening the door to the New Hebrides and New Caledonia. This would be followed by the capture of Midway and the western Aleutians in June. In July it would be the turn of Fiji and Samoa. Finally, Hawaii would be assaulted in October. Yamamoto believed that "As a result of the smooth progress of the first-phase operations, we have established an invincible strategic position [that] cannot be maintained if we go on the defensive.... in order to secure it tenaciously, we must keep on striking offensively at the enemy's weak points one after another" (Lundstrom 2006).
In retrospect, Japanese plans for the Second Operational Phase were completely unrealistic and it should not be a surprise that the Allies managed to stop them cold. The Battle of the Coral Sea frustrated the attempt to seize Port Moresby, but Yamamoto chose to regard this as a minor and temporary setback and proceeded with the Midway operation. The battle of Midway was a disaster for Japan. The Japanese Navy lost most of its first-line carriers, a blow from which it never fully recovered. The battle restored the balance of power in the Pacific, and the Americans seized the strategic initiative with the counteroffensive at Guadalcanal.
Any remaining thoughts of advancing against Fiji and Samoa were quietly dropped when the Americans could not be dislodged from Guadalcanal.
July 1942 - February 1943: The Guadalcanal and Buna Campaigns. Although the battle of Midway had restored the balance of power in the Pacific, it was not the turning point of the war. This came at Guadalcanal, where the Americans surprised the Japanese by seizing the uncompleted airfield on the north coast of the island. The Japanese campaign to recapture the airfield, and the American effort to hold it, soon became the main effort of both powers in the Pacific. The campaign included two major carrier battles (Eastern Solomons and Santa Cruz) and one battleship engagement as well as numerous other surface and ground battles. The Americans succeeded in holding Guadalcanal, and, in the process, ground down the Japanese naval air force and destroyer flotillas in a brutal battle of attrition.
At the same time, MacArthur's forces ground forward in eastern New Guinea with the goal of seizing the approaches to Rabaul from the west. The first step was to recapture Buna. This turned into another bloody battle of attrition, but by February 1943 the Japanese had been ejected from the Buna area.
By this time Tojo was
dictating Japan's grand strategy.
December 1942 Tojo presided over a conference of Imperial General Headquarters
held in the presence of the Emperor. Tojo chose this venue to
the influence of Sugiyama Gen,
the Army chief of staff, with whom Tojo was then struggling for
of the Army. Tojo already had the full support of the Navy
Minister, Shimada Shigetaro,
an hour and forty minutes Tojo dictated future strategy.
and Buna would be abandoned and a new defensive line would be held
north of New Georgia in the
Solomons. Meanwhile Japanese positions in New Guinea would be
reinforced and a new drive launched against Port Moresby. The
Wau offensive was turned back by the
February 1943 - July 1943: The Aleutians Campaign. As Allied forces regrouped in the South and Southwest Pacific, the Americans conducted a brief campaign to eject the Japanese from the western Aleutians, which they had seized during the Midway campaign. The campaign came to a successful end with the seizure of Kiska on 29 July 1943.
June 1943 - March
1944: Isolating Rabaul.
strategy in the Southwest
Pacific was initially focused on recapturing Rabaul, and MacArthur envisioned a
two-pronged counteroffensive (CARTWHEEL)
with one prong coming up the Solomons and the other across the
and Vitiaz Straits from New Guinea to New Britain. However, the
operations to secure Guadalcanal
in the Solomons and to clear the northeast coast of New
Guinea around Buna had been far
and taken far longer than expected. By the time the Allied South
forces had completed the Solomons campaign by advancing through New Georgia (30 June 1943) and Vella Lavella (15 August 1943)
to Bougainville (1 November
and the Southwest
Pacific forces had finally cleared the New Guinea coast as far as
Lae (16 September 1943) and Finschhafen (22 September 1943)
and crossed to Cape
Gloucester (26 December 1943), it had become clear just how
a fortress the
Japanese had made of Rabaul. The Allies chose to bypass Rabaul,
was neutralized by air power and left to wither on the vine. The
Admiralty Islands were assaulted on 1 March 1944, the Green Islands on 15 February
1944, and Emirau on 20 March 1944
to forge the
last links in the ring around Rabaul.
CARTWHEEL proved to be the decisive campaign of the Pacific War, breaking Japanese air power while pinning down the Japanese Navy until the massive U.S. naval expansion began coming off the ways in late 1943.
November 1943 - September 1944: The Great Allied Counteroffensives Begin. On 20 November 1943, the long-anticipated Central Pacific offensive got underway with the assault by 2 Marine Division on Tarawa. The battle came close to becoming a bloody shambles, but the Japanese garrison was finally overcome and the lessons learned were put to good use in later invasions. These followed far more quickly than the Japanese believed possible: Kwajalein (31 January), Eniwetok (18 February), the Marianas (15 June), and Peleliu (15 September). The assault on the Marianas led to the penultimate carrier clash of the war, the Battle of the Philippine Sea, which ended in a decisive American victory.
Meanwhile MacArthur began his own counteroffensive
along the north coast of New Guinea towards the Philippines.
good use of intelligence provided by Allied code breakers, MacArthur sidestepped
the main Japanese forces, landing successively at Aitape and Hollandia
(22 April 1944), Wakde (18 May), Biak (27 May), Noemfoor
(2 July), Sansapor (30 July 1944),
and Morotai (15 September).
Mountbatten began his own counteroffensive in Burma in January 1944, advancing in the Arakan and against Mytkyina. The Japanese counterattacked at Imphal and Kohima in March 1944, but the British held and the Japanese retreat turned into a rout.
October 1944 -
July 1945: The End Game. The final Allied strategy for
the war was mapped out at the San Francisco Conference on 29
September — 1 October 1944. The Americans in the Pacific were
poised to seize either the Philippines or Formosa,
with MacArthur favoring the former and King
favoring the latter. Roosevelt resolved the strategic deadlock in
of the Philippines, and Nimitz developed a plan for subsequent
operations based on a staggered offensive along two axes. The
prong of the offensive would climb the Nanpo Shoto while the second
would advance through the Ryukyu
Islands. This plan made heavy demands on the U.S. Pacific Fleet,
which would have to cover the invasion of the Philippines, then
alternate between covering the two prongs of the advance. This
adopted by the Joint Chiefs of Staff on 3 October 1945.
MacArthur invaded Leyte on 20 October 1944. This precipitated the last major naval battle of the war, the Battle of Leyte Gulf, which was another decisive American victory and spelled the near-destruction of the Japanese Navy. MacArthur then invaded Mindoro (15 December) and Luzon (9 January 1945), capturing the prize of Manila on 3 March.
Attention now turned to the inner defenses of the home island of Japan itself. The inner defense zone was defined by the Japanese in the "Outline of Army and Navy Operations" promulgated on 20 January 1945. The major strongpoints in this zone were Okinawa, Iwo Jima, Formosa, Shanghai, and southern Korea. Iwo Jima was invaded on 19 February 1945 and Okinawa on 1 April. Both were protracted, bloody battles against fanatical resistance. However, the U.S. Army Air Forces had already begun a devastating strategic bombing campaign from bases in the Marianas.
Meanwhile, Slim crossed the Chindwin into central Burma in December 1944 and fought a great battle on the east bank of the Irrawady that had essentially destroyed Burma Area Army by the end of March 1945. The campaign turned into a race to reach Rangoon before the monsoons broke. Rangoon was taken on 2 May 1945.
Japan was now cut off from its foreign conquests
and its cities were being systematically burned to the ground.
the Japanese Army refused to consider surrender,
believing that it was still possible to turn back the Allied
of Japan itself (DOWNFALL) and
Allies to accept something less than an unconditional surrender.
hope proved vain when the Americans dropped nuclear bombs on Hiroshima (6 August 1945) and Nagasaki (8 August) and the Russians
invaded Manchuria (9 August). The Emperor finally persuaded his
government to surrender on 9 August 1945. The surrender was
on 15 August, though the instrument of surrender was not actually
signed until 2 September and scattered fighting continued to 8
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