Pacific War

• 1. Introduction

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  The Pacific War was the largest theater of World War II by geography, stretching across the Pacific and Indian Oceans, East and Southeast Asia, and Oceania. By the time it ended on the 2nd of September 1945, it had consumed nations, navies, and tens of millions of lives across a vast stretch of the globe. At its center stood one question that had no clean answer: could Japan hold enough territory, long enough, to force the United States into a negotiated peace?

  This was not a war that began at Pearl Harbor. Japan had invaded Manchuria in 1931, and the full-scale war with China started in 1937. By the eve of the Pearl Harbor attack, some 7,500,000 Chinese soldiers and civilians had already died. The wider conflict that drew in the United States, Britain, and their allies in December 1941 layered onto a war already four years old.

  What follows is the story of how that conflict unfolded across five years of fighting: the stunning early Japanese advances, the brutal turning points in the Coral Sea and at Midway, the grinding attrition on Guadalcanal, the slow Allied island-hopping march toward Japan, and the atomic bombings that finally brought the war to a close.

• 2. War Before the War

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  Japan invaded Manchuria in 1931 without declaring war, seeking raw materials to fuel its growing industrial economy. By 1937, Japan controlled Manchuria and was ready to push deeper into China. The Marco Polo Bridge Incident on the 7th of July 1937 triggered full-scale war between the two countries.

  China's Nationalist Party and the Communist Party suspended their civil war to form a nominal alliance against Japan. Generalissimo Chiang Kai-shek deployed some of his best troops to defend Shanghai against roughly 300,000 Japanese troops. The city fell after three months. The Japanese then captured the capital Nanjing in mid-December 1937, committing the atrocities of the Nanjing Massacre, including rape, murder, and torture.

  Japan scored major military victories across China, but could not destroy the Chinese army. The Nationalist government retreated to Chongqing; the Communists held base areas in Shaanxi. Japanese strategic bombing campaigns targeting large Chinese cities ran from February 1938 to August 1943, killing between 260,000 and 350,934 non-combatants. In retaliation for a 1940 Chinese Communist offensive, Japan instituted the Three Alls Policy in occupied areas, killing at least 2.7 million civilians.

  In 1939, Japan tried to expand northward into Soviet territory. A mixed Soviet and Mongolian force led by Georgy Zhukov defeated the Japanese at the Battle of Khalkhin Gol, ending any ambition to push north. Japan turned southward instead, invading French Indochina in September 1940 and signing a military alliance with Germany and Italy on the 27th of that month. Western powers responded with embargoes on oil, iron ore, and steel. Imported oil made up about 80% of Japan's domestic consumption, and the Japanese government viewed these embargoes as acts of aggression.

• 3. Pearl Harbor and the Opening Blows

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  On the 7th of December 1941, carrier-based Japanese aircraft struck the US Pacific Fleet's anchorage at Pearl Harbor in Honolulu. Eight American battleships were knocked out of action, 188 American aircraft were destroyed, and 2,403 Americans were killed. Japan had not delivered its declaration of war before the bombs fell, a fact that produced a wave of outrage across the United States and dissolved all domestic opposition to entering the conflict.

  Japan's planners had hoped the blow would be decisive. It was not. The three American aircraft carriers were at sea during the attack. The submarine base, vital naval infrastructure, and signals intelligence units were untouched. Japan's fallback strategy of fighting a war of attrition against the United States was, as Japanese planners themselves understood, beyond the Imperial Japanese Navy's actual capabilities.

  The same day, Japanese forces struck American territories in the Philippines, Guam, and Wake Island, and the British colonies of Malaya, Singapore, and Hong Kong. Thailand surrendered within hours. Hong Kong fell on the 25th of December 1941. Two major British warships, a battlecruiser and a battleship, were sunk by Japanese aircraft off Malaya on the 10th of December.

  The fall of Singapore on the 15th of February 1942 was among the worst Allied disasters of the war. About 130,000 Indian, British, Australian, and Dutch personnel became prisoners of war. In Burma, the Japanese captured Moulmein on the 31st of January 1942 and then drove Allied troops toward the Sittang River, where a bridge was demolished prematurely on the 23rd of February, stranding most of an Indian division. Darwin, on the Australian mainland, was bombed on the 19th of February 1942, killing at least 243 people. It was the first time Australia had come under foreign attack.

• 4. Midway: The Hinge Point

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  Admiral Yamamoto viewed the operation against Midway Atoll as potentially the decisive battle of the Pacific War. His plan was to knock out Midway's air defenses, land 5,000 troops, and use the island as bait to lure the American fleet into a trap where his concentrated forces could destroy it. The problem was that American codebreakers discovered the plan in May 1942.

  Yamamoto's complex strategy contained no contingencies for being found early. Planned surveillance of the American fleet by long-range seaplanes failed. Japanese submarine scouting lines along the Hawaiian Islands were not in position on time. When the battle began on the 3rd of June, American aircraft from Midway spotted and attacked the Japanese transport group 700 miles west of the atoll.

  On the 4th of June, Japan launched a 108-aircraft strike on Midway but failed to deliver a decisive blow to the island's facilities. In the middle of uncoordinated attacks by American ground-based aircraft, a Japanese scout aircraft reported the presence of an American task force. Vice Admiral Chuichi Nagumo chose to delay and better prepare an attack on the American ships. At 10:22 in the morning, American SBD Dauntless dive bombers caught three Japanese carriers by surprise. Soryū, Kaga, and Akagi were destroyed in short order.

  The sole surviving Japanese carrier, Hiryū, launched an immediate counterattack that put Yorktown out of action. But aircraft from the two remaining American carriers then found and destroyed Hiryū. The crippled Yorktown, along with a destroyer, were later sunk by a Japanese submarine. Four Japanese fleet carriers, the core of the Kido Butai, were gone. Japan would experience great difficulty replacing those losses in ships and aircraft as the United States produced ever-increasing numbers of both.

• 5. Guadalcanal and the Cost of Attrition

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  Allied coastwatchers spotted a Japanese airfield under construction at Guadalcanal in the Solomon Islands. On the 7th of August 1942-16,000 US Marines landed on Guadalcanal and the nearby island of Tulagi. What followed was six months of relentless, escalating battle that drained Japan of resources it could not replace.

  Vice Admiral Gunichi Mikawa moved quickly, bringing the newly formed IJN Eighth Fleet down from Rabaul. On the night of the 8th-the 9th of August, his ships surprised Allied naval forces in the Battle of Savo Island, sinking four Allied heavy cruisers while suffering no losses of their own. The battle was one of the worst Allied naval defeats of the war. Mikawa's failure to then attack the vulnerable Allied transport ships may have been the campaign's single most consequential missed opportunity.

  For months, Japanese and Allied forces poured resources into Guadalcanal. American ground-based aircraft at Henderson Field held control of the surrounding waters during daylight. The IJN used its superior night-fighting capabilities to run supply convoys after dark, a route the Allies called the Tokyo Express. During the night of the 13th of October, Japanese battleships Kongo and Haruna bombarded Henderson Field and temporarily disabled it. American engineers returned it to service quickly. On the 26th of October, Japanese carriers Shokaku and Zuikaku sank the American carrier Hornet and heavily damaged Enterprise in the Battle of the Santa Cruz Islands, reducing US carrier strength in the region to a single vessel.

  But the Japanese were committing their forces piecemeal, and the Allies were far better able to replace losses. By late 1942, Japan chose to evacuate. Over the six-month campaign, more than 25,000 Japanese soldiers died on Guadalcanal, with roughly 15,000 having starved to death. Just over 7,000 Americans died. The attrition on Guadalcanal also forced Japan to cancel Operation Gogo, its planned strike into the Sichuan Basin aimed at overthrowing the Chinese Nationalist government.

• 6. Submarine War Beneath the Surface

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  Within hours of Pearl Harbor, President Roosevelt promulgated a new doctrine: unrestricted submarine warfare against Japanese shipping. This meant sinking any warship, commercial vessel, or passenger ship in Japanese-controlled waters, without warning and without aiding survivors. It was a policy with profound consequences for Japan's war-making capacity.

  American, British, and Dutch submarines operated from bases at Cavite in the Philippines, Fremantle and Brisbane in Australia, Pearl Harbor, Trincomalee in Ceylon, and later Guam. They strangled Japanese commercial and military shipping, cutting off nearly all of the oil imports essential to weapons production and military operations. By early 1945, Japanese oil supplies were so limited that the remaining IJN fleet was virtually stranded in port.

  Results were not immediate. The standard-issue Mark 14 torpedo and its Mark VI exploder both proved defective and were not corrected until September 1943. A US Navy code breakthrough that would have let submarines find their targets was set back when a US Customs officer had seized a copy of the Japanese merchant marine code before the war, inadvertently tipping Japan to change it; the new code was not broken again until 1943. But once those problems were fixed, the numbers rose steeply: 350 submarine patrols and 180 ships sunk in 1942, 350 patrols and 335 ships sunk in 1943, and 520 patrols and 603 ships sunk in 1944.

  In total, Allied submarines destroyed approximately 1,200 Japanese merchant ships, about five million tons of shipping. American submariners also accounted for 28% of all Japanese warships destroyed, including a battleship and at least eight carriers. The work came at a terrible cost: of the 16,000 Americans who went out on submarine patrol, 3,500 never returned, a casualty rate of 22%, the highest of any American force in World War II.

• 7. Island Hopping to Japan

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  From November 1943 onward, the Allies executed a methodical advance across the Central Pacific, seizing island bases in a series of amphibious assaults while bypassing heavily fortified Japanese strongholds like Truk and Rabaul through air attack and neutralization. The goal was not to fight every Japanese garrison; it was to get close enough to Japan to begin a strategic bombing campaign and tighten a submarine blockade.

  US Marine forces suffered high casualties when they overwhelmed the 4,500-strong Japanese garrison at Tarawa Atoll in November 1943. That painful experience drove improvements in amphibious technique, including thorough pre-landing aerial bombardment, more careful planning around tides and landing schedules, and better unit coordination. Operations in the Marshall Islands followed in late January and mid-February 1944, at considerably less cost.

  In the Battle of the Philippine Sea in June 1944, the Japanese fleet took heavy damage, and the Allied campaign to recapture the Philippines began in October. The resulting Battle of Leyte Gulf was so decisive that the Japanese were unable to fight further surface engagements and resorted to kamikaze attacks. In May 1944, for the Marianas operation, the US Joint Chiefs of Staff had assembled a force of 535 warships and auxiliaries along with a ground force of over 127,500 troops. Securing the Marianas allowed construction of airfields from which B-29 bombers could reach the Japanese home islands.

  In Burma, the Japanese launched Operation U-Go into India in mid-March 1944, a long-planned offensive advocated by Lieutenant General Renya Mutaguchi. The Japanese advanced as far as Kohima in Nagaland, but their supply lines across jungle trails could not sustain the campaign. By the 3rd of July, Japan broke off the operation having lost over 50,000 troops, mainly to starvation and disease, the worst defeat the Imperial Japanese Army had suffered to that point.

• 8. Surrender and Its Aftermath

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  After Germany surrendered in May 1945, Allied forces that had followed a Europe-first strategy began shifting to the Pacific in preparation for Operation Downfall, a planned invasion of the Japanese home islands. Planning assumed enormous casualties on both sides.

  That invasion never came. On the 6th of August 1945, the United States dropped an atomic bomb on Hiroshima. On the 9th of August, a second bomb fell on Nagasaki. The same day, the Soviet Union, honoring a commitment made at the Allied conferences, invaded Manchuria. Japan surrendered unconditionally on the 15th of August 1945 and signed the formal surrender document on the 2nd of September, ending World War II.

  Japan lost all of its former possessions in Asia and the Pacific. Allied occupation of Japan lasted until 1952. The terms Japan had hoped to win through rapid conquest, a negotiated peace that recognized Japanese hegemony in Asia, never materialized. The leadership had understood from the beginning that total military victory over the United States was impossible; the gamble had been that the Americans would tire of fighting and agree to terms. They did not.

  The Occupation prohibited the terms Greater East Asia War and the names Japan had used for the conflict in official documents, though informal usage continued. The period from the Mukden Incident of 1931 through 1945 eventually acquired its own designation in Japanese historical memory, marking the full arc of a war that had begun not with Pearl Harbor but with a 1931 incursion into Manchuria, fourteen years before the last shot was fired.