The Pacific War, also called sometimes the Asia-Pacific War refers broadly to the parts of World War II that took place in the Pacific Ocean, its islands, and in the Far East. The term Pacific War is used to encompass the Pacific Ocean theatre, the South West Pacific theatre, the South-East Asian theatre and the Chinese theatre, also including the 1945 Soviet-Japanese conflict. It is generally considered that the Pacific War began on 7 December 1941 with the invasion of British Malaya and the attack on Pearl Harbor in the United States' Territory of Hawaii by the Empire of Japan. Some authors consider that the conflict in Asia can be dated as far as July 7, 1937, beginning with the Second Sino-Japanese War between the Empire of Japan and the Republic of China, or possibly September 19 1931, beginning with the Japanese invasion of Manchuria. However, it is more generally accepted that the Pacific war itself started in December 1941, with the Sino-Japanese war then becoming part of it as a theatre of the greater World War II. The Pacific War saw the Allied powers against the Empire of Japan, the latter aided by Thailand and to lesser extent by its Axis allies Germany and Italy : it culminated in the atomic bombings of Hiroshima and Nagasaki by the United States and the Soviet invasion of Manchuria, resulting in Victory over Japan Day and the end of World War II on August 15, 1945. The surrender of Japan occurred aboard the battleship USS Missouri on September 2, 1945.
In Allied countries during the war, it was not usually distinguished from the Second World War in general, or was known simply as the War with Japan. In the US, the term Pacific Theater was widely used, although technically this did not cover the China or Southeast Asia theaters. These regions were covered under the CBI Theater of Operations.
Japan used the name Greater East Asia War (大東亜戦争 Dai Tō-A Sensō ), as chosen by a cabinet decision on December 10, 1941, to refer to both the war with the Western Allies and the ongoing war in China. The name was released to the public on December 12, with an explanation that it involved Asian nations achieving independence from the Western powers through the Greater East Asia Co-prosperity Sphere. Japanese officials integrated what they called the Japan-Sino Incident (日支事変 Nisshi Jihen ) into the Greater East Asia War.
During the American occupation, these terms were prohibited in official documents, although informal usage continued, and the war became officially known as Pacific War (太平洋戦争 Taiheiyō Sensō ). This latter term has come into broad use in occidental countries since. In Japan, Fifteen Year War (十五年戦争 Jūgonen Sensō ) is also used, referring to the period from the Mukden Incident of 1931 until 1945.
The Axis states which assisted Japan included the authoritarian government of Thailand, which quickly parlayed an alliance with the Japanese in 1941 as Japanese forces were invading Thailand's Southern peninsula, and sent forces to invade and occupy northeastern Burma, territories of Thailand that had been forcibly taken by the British. The Japanese puppet states of Manchukuo (parts of Manchuria and Inner Mongolia) and the Wang Jingwei Government (which controlled the coastal regions of China). Japan enlisted many soldiers from its colonies of Korea and Formosa (later known as Taiwan). To a small extent, some Vichy French, Indian National Army, and Burmese National Army forces were active in the area. To an even smaller extent, German and Italian naval forces (mainly armed merchantmen and submarines) also operated in the Pacific and Indian Oceans.
The major Allied participants were the United States, China, the United Kingdom (including the forces of British India), Australia, the Philippine Commonwealth, the Netherlands (as possessor of the Dutch East Indies), New Zealand, and Canada, all of whom were members of the Pacific War Council. Mexico, Free France and many other countries also took part, especially forces from other British colonies and also Latin America.
The Soviet Union fought two short, undeclared border conflicts with Japan in 1938 and 1939, then remained neutral until August 1945, when it joined the Allies and invaded the territory of Manchukuo, Republic of China, Inner Mongolia, the Japanese protectorate of Korea and Japanese-claimed islands such as Sakhalin coordinated notably between the Red Banner Pacific Fleet and the US Navy's Task Force 38.
Between 1942 and 1945, there were four main areas of conflict in the Pacific War: China, the Central Pacific, South East Asia and the South West Pacific. U.S. sources refer to two theaters within the Pacific War: the Pacific Theater of Operations (PTO) and the China Burma India Theater (CBI). However these were not operational commands. In the PTO, the Allies divided operational control of their forces between two supreme commands, known as Pacific Ocean Areas and Southwest Pacific Area. In 1945, for a brief period just before the Japanese surrender, the Soviet Union and its Mongolian ally engaged Japanese forces in Manchuria and northeast China.
The roots of the Second Sino-Japanese War began in the late 19th century with China in political chaos and Japan rapidly modernizing. Over the course of the late 19th century and early 20th century, Japan intervened and finally annexed Korea and expanded its political and economic influence into China, particularly Manchuria. This expansion of power was aided because by the 1910s, China had fragmented into warlordism with only a weak and ineffective central government.
However, the situation of a weak China unable to resist Japanese demands appeared to be changing toward the end of the 1920s. In 1927, Generalissimo Chiang Kai-shek and the National Revolutionary Army of the Kuomintang (KMT) led the Northern Expedition. Chiang was able to defeat the warlords in southern and central China, and secured the nominal allegiance of Zhang Xueliang, the warlord controlling Manchuria, which resulted in the nominal unification of China in 1928. Alarmed at the strengthening of China under one government, the Japanese staged the Mukden Incident in 1931, using it as a pretext for an invasion of Manchuria and set up the puppet state of Manchukuo. Henry Pu Yi, the last emperor of the defunct Qing Dynasty, became the figure head for Manchukuo.
Japan's imperialist goals in China were to maintain a secure supply of natural resources and to have puppet governments in China that would not act against Japanese interests. Although Japanese actions would not have seemed out of place among European colonial powers in the 19th century, by 1930, increasing anti-colonialism meant overt military force in support of colonialism was no longer as acceptable as before.
Hence Japanese actions in Manchuria were roundly criticized and led to Japan's withdrawal from the League of Nations. During the 1930s, China and Japan reached a stalemate with Chiang focusing his efforts at eliminating the Communist Party of China, whom he considered to be a more fundamental danger than the Japanese. The influence of Chinese nationalism on opinion both in the political elite and the general population rendered this strategy increasingly untenable.
Though they had at first cooperated in the Northern Expedition, during the period of 1930–34, the nationalist KMT and the Chinese Communist Party entered into direct conflict. The Japanese capitalized on the infighting between Chinese factions to make greater inroads, forcing a landing at Shanghai in 1932.
Meanwhile, in Japan, a policy of assassination by secret societies and the effects of the Great Depression had caused the civilian government to lose control of the military. In addition, the military high command had limited control over the field armies who acted in their own interest, often in contradiction to the overall national interest, but usually in keeping with Emperor Hirohito's wishes. Pan-Asianism was also used as a justification for Japanese expansion. This is perhaps best summarized by the "Amo Doctrine" of 1934, issued by Eiji Amo, head of information department of the Japanese Foreign Ministry. Known as the "Monroe Doctrine of Asia", it announced Japan's intention for European countries to adopt a "hands off" policy in China, thereby negating the Open Door Policy. It stated that Japan was to be the sole leader in security in East Asia, including the task of defeating communism. Economics was also a very important factor leading to the invasion of China. During the Depression, Japanese exports to American and European markets were severely curtailed, and Japan turned to completely dominating China politically and economically to provide a stable market. In the period leading up to full-scale war in 1937, Japan used force in localised conflicts to threaten China unless the latter reduced its protective tariff and suppressed anti-Japanese activities and boycotts.
In 1936, Chiang was kidnapped by Zhang Xueliang. As a condition of his release, Chiang agreed to form a united front with the communists and fight the Japanese. Soon after, the Marco Polo Bridge Incident took place on July 7, 1937, which succeeded in provoking a war between the Republic of China and the Empire of Japan. Though the Nationalist and Communist Chinese would cooperate in military campaigns against Japan and sought to create a united national front, Mao Zedong refused Chiang's wish to directly control communist forces. In 1939, the Chinese Communist Red Army consisted of 500,000 troops independent of the KMT.
In addition, throughout the 1930s Japan succeeded in alienating public opinion in the West, particularly the United States and Britain. During the early 1930s, public opinion in the United States had been neutral. However, news reports of the Panay incident caused American public opinion to swing against Japan.
In 1939 Japanese forces tried to push into the Soviet Far East from Manchuria. They were soundly defeated in the Battle of Khalkhin Gol by a mixed Soviet and Mongolian force led by Georgy Zhukov. This stopped Japanese expansion to the north, and Japan and the Soviet Union kept an uneasy peace until 1945.
In September 1940, Japan attempted to cut Chinese links with other countries by obtaining approval for bases in French Indochina, which was controlled at the time by Vichy France. Japanese forces broke the terms of their agreement with the Vichy administration and fighting broke out, ending in a Japanese victory. On September 27, Japan signed a military alliance with Germany and Italy.
By 1941, the conflict had become a stalemate. Although Japan had occupied much of northern and central China, the Kuomintang had retreated to the interior with a provisional capital set up at Chungking while the Chinese communists remained in control of base areas in Shaanxi. In addition, Japanese control of northern and central China was somewhat tenuous, in that Japan was usually able to control railroads and the major cities ("points and lines"), but did not have a major military or administrative presence in the vast Chinese countryside. The Japanese found its aggression against the retreating and regrouping Chinese army was stalled by the mountainous terrain in southwestern China while the Communists organised widespread guerrilla and saboteur activities in northern and eastern China behind the Japanese front line.
Japan sponsored several puppet governments, one of which was headed by Wang Jingwei. However, its policies of brutality toward the Chinese population, of not yielding any real power to the governments, and of supporting several rival governments failed to make any of them a popular alternative to Chiang's government. Japan was also unwilling to negotiate directly with Chiang, nor was it willing to attempt to create splits in the Chinese united front.
In an effort to discourage Japanese militarism, Western powers including Australia, the United States, Britain, and the Dutch government in exile, which controlled the petroleum-rich Netherlands East Indies, stopped selling iron ore, steel and oil to Japan, denying it the raw materials needed to continue its activities in China and French Indochina. In Japan, the government and nationalists viewed these embargos as acts of aggression; imported oil made up about 80% of domestic consumption, without which Japan's economy, let alone its military, would grind to a halt. The Japanese media, influenced by military propagandists, began to refer to the embargoes as the "ABCD ("American-British-Chinese-Dutch") encirclement" or "ABCD line".
Faced with a choice between economic collapse and withdrawal from its recent conquests (with its attendant loss of face), the Japanese Imperial General Headquarters began planning for a war with the western powers in April or May 1941.
The key objective was for the Southern Expeditionary Army Group to seize economic resources under the control of the United Kingdom and the Netherlands, most notably those in Malaya and the Netherlands East Indies, known as the "Southern Plan". It was also decided—because of the close relationship between the UK and United States, and the (mistaken) belief the US would inevitably become involved—Japan would also require an "eastern plan".
The eastern plan required
The southern plans called for:
Following completion of these objectives, the strategy would turn defensive, primarily holding their newly acquired territory while hoping for a negotiated peace.
By November these plans were essentially complete, and were modified only slightly over the next month. Japanese military planners' expectation of success rested on the United Kingdom and the Soviet Union being unable to effectively respond to a Japanese attack because of the threat posed to each by Germany; the Soviet Union was even seen as unlikely to commence hostilities.
There is no evidence the Japanese planned to defeat the United States; the alternative would be negotiating for peace after their initial victories. In fact, the Imperial GHQ noted, should acceptable negotiations be reached with the Americans, the attacks were to be canceled—even if the order to attack had already been given.
They also planned, should the U.S. transfer its Pacific Fleet to the Philippines, to intercept and attack this fleet en route with the Combined Fleet, in keeping with all Japanese Navy prewar planning and doctrine.
Should the United States or Britain attack first, the plans further stipulated the military were to hold their positions and wait for orders from GHQ. The planners noted attacking the Philippines and Malaya still had possibilities of success, even in the worst case of a combined preemptive attack including Soviet forces.
Nazi Germany and Fascist Italy both had limited involvement in the Pacific War. The German Navy (Kriegsmarine) and the Italian Royal Navy (Regia Marina) operated submarines and raiding ships in the Indian and Pacific Oceans. The Italians had access to "concession territory" naval base in China while the Germans did not. After Japan's attack on Pearl Harbor and the subsequent declarations of war, both navies had access to Japanese naval facilities.
On December 8, 1941, Japanese forces attacked the British crown colony of Hong Kong and the US-controlled Commonwealth of the Philippines. Japan also used its bases in French Indochina to invade Thailand, then using the gained Thai territory to launch an assault against Malaya.
On 7 December (8 December in the Eastern Hemisphere), Japan launched a carrier-based air attack on Pearl Harbor, knocking eight American battleships out of action. The Japanese had gambled that the United States, when faced with such a sudden and massive defeat, would agree to a negotiated settlement and allow Japan free rein in China. This gamble did not pay off. American losses were less serious than initially thought: the American aircraft carriers, far more important than battleships, were at sea, and vital naval infrastructure (fuel oil tanks and the shipyard facilities), submarines and signals intelligence units were unscathed. Japan's fallback strategy, relying on a war of attrition to make the US come to terms, was beyond the IJN's capabilities.
When the attack on Pearl Harbor occurred, the United States was not at war anywhere in the world. The America First Committee, 800,000 members strong, had vehemently opposed any American intervention in the foreign conflict, even as America sold military aid to Britain and the Soviet Union, through the Lend-Lease program. Opposition to war in the United States vanished after the attack. On December 7, Australia declared war on Japan. On December 8, Netherlands declared war on Japan. Four days after Pearl Harbor, Nazi Germany and Fascist Italy declared war on the United States, drawing the country into a two-theater war. This is widely agreed to be a grand strategic blunder, as it abrogated the benefit Germany gained by Japan's distraction of the U.S. (predicted months before in a famous memo by Commander Arthur McCollum), and the reduction in aid to Britain, which both Congress and Hitler had managed to avoid during over a year of mutual provocation, which would otherwise have resulted.
|“||I praise the Army for cutting down like weeds large numbers of the enemy...||”|
British, Australian and Dutch forces, already drained of personnel and matériel by two years of war with Germany, and heavily committed in the Middle East, North Africa and elsewhere, were unable to provide much more than token resistance to the battle-hardened Japanese. The Allies suffered many disastrous defeats in the first six months of the war. Two major British warships, HMS Repulse and HMS Prince of Wales were sunk by a Japanese air attack off Malaya on December 10, 1941.
Thailand, with its territory already serving as a springboard for the Malayan campaign, surrendered within 24 hours of the Japanese invasion. The government of Thailand formally allied itself with Japan on December 21.
Hong Kong was attacked on December 8 and fell on December 25, 1941, with Canadian forces and the Royal Hong Kong Volunteers playing an important part in the defense. U.S. bases on Guam and Wake Island were lost at around the same time.
Following the January 1, 1942 Declaration by United Nations (the first official use of the term United Nations), the Allied governments appointed the British General Sir Archibald Wavell to the American-British-Dutch-Australian Command (ABDACOM), a supreme command for Allied forces in South East Asia. This gave Wavell nominal control of a huge force, albeit thinly-spread over an area from Burma to the Philippines to northern Australia. Other areas, including India, Hawaii and the rest of Australia remained under separate local commands. On January 15, Wavell moved to Bandung in Java to assume control of ABDA Command (ABDACOM).
In January, Japan invaded Burma, the Dutch East Indies, New Guinea, the Solomon Islands and captured Manila, Kuala Lumpur and Rabaul. After being driven out of Malaya, Allied forces in Singapore attempted to resist the Japanese during the Battle of Singapore but surrendered to the Japanese on February 15, 1942; about 130,000 Indian, British, Australian and Dutch personnel became prisoners of war. The pace of conquest was rapid: Bali and Timor also fell in February. The rapid collapse of Allied resistance had left the "ABDA area" split in two. Wavell resigned from ABDACOM on February 25, handing control of the ABDA Area to local commanders and returning to the post of Commander-in-Chief, India.
Meanwhile, Japanese aircraft had all but eliminated Allied air power in South-East Asia and were making attacks on northern Australia, beginning with a psychologically devastating (but militarily insignificant) attack on the city of Darwin on February 19, which killed at least 243 people.
At the Battle of the Java Sea in late February and early March, the Japanese Navy inflicted a resounding defeat on the main ABDA naval force, under Admiral Karel Doorman. The Netherlands East Indies campaign subsequently ended with the surrender of Allied forces on Java.
In March and April, a raid into the Indian Ocean by a powerful Imperial Japanese Navy aircraft carrier force resulted in a wave of major air raids against Ceylon and the sinking of a British aircraft carrier, HMS Hermes as well as other Allied ships and driving the British fleet out of the Indian Ocean. This paved the way for a Japanese assault on Burma and India.
The British, under intense pressure, made a fighting retreat from Rangoon to the Indo-Burmese border. This cut the Burma Road which was the western Allies' supply line to the Chinese Nationalists. Cooperation between the Chinese Nationalists and the Communists had waned from its zenith at the Battle of Wuhan, and the relationship between the two had gone sour as both attempted to expand their area of operations in occupied territories. Most of the Nationalist guerrilla areas were eventually overtaken by the Communists. On the other hand, some Nationalist units were deployed to blockade the Communists and not the Japanese. Furthermore, many of the forces of the Chinese Nationalists were warlords allied to Chiang Kai-Shek, but not directly under his command. "Of the 1,200,000 troops under Chiang's control, only 650,000 were directly controlled by his generals, and another 550,000 controlled by warlords who claimed loyalty to his government; the strongest force was the Szechuan army of 320,000 men. The defeat of this army would do much to end Chiang's power." The Japanese exploited this lack of unity to press ahead in their offenses.
Filipino and U.S. forces resisted in the Philippines until May 8, 1942, when more than 80,000 soldiers were ordered to surrender. By this time, General Douglas MacArthur, who had been appointed Supreme Allied Commander South West Pacific, had retreated to the safer confines of Australia. The U.S. Navy, under Admiral Chester Nimitz, had responsibility for the rest of the Pacific Ocean. This divided command had unfortunate consequences for the commerce war, and consequently, the war itself.
|“||For every advance that the Japanese have made since they started their frenzied career of conquest, they have had to pay a very heavy toll in warships, in transports, in planes, and in men. They are feeling the effects of those losses.||”|
— Franklin D. Roosevelt, 28 April 1942
In early 1942, the governments of smaller powers began to push for an inter-governmental Asia-Pacific war council, based in Washington, D.C.. A council was established in London, with a subsidiary body in Washington. However the smaller powers continued to push for a U.S.-based body. The Pacific War Council was formed in Washington, on April 1, 1942, with President Franklin D. Roosevelt, his key advisor Harry Hopkins, and representatives from Britain, China, Australia, the Netherlands, New Zealand, and Canada. Representatives from India and the Philippines were later added. The council never had any direct operational control, and any decisions it made were referred to the U.S.-UK Combined Chiefs of Staff, which was also in Washington.
Allied resistance, at first symbolic, gradually began to stiffen. Australian and Dutch forces led civilians in a prolonged guerilla campaign in Portuguese Timor. The Doolittle Raid did minimal damage but was a huge morale booster for the Allies, especially the United States, and it caused repercussions throughout the Japanese military because they were sworn to protect the Japanese emperor and homeland, but did not intercept, down, or damage a single bomber. The greatest effect of the raid, however, was that it caused the Japanese to launch the ultimately catastrophic assault on Midway.
By mid-1942, the Japanese Combined Fleet found itself holding a vast area, even though it lacked the aircraft carriers, aircraft, and aircrew to defend it, and the freighters, tankers, and destroyers necessary to sustain it. Moreover, Fleet doctrine was inadequate to execute the proposed "barrier" defence. Instead, they decided on additional attacks in both the south and central Pacific. While Yamamoto had used the element of surprise at Pearl Harbor, Allied codebreakers now turned the tables. They discovered an attack against Port Moresby, New Guinea, was imminent with intent to invade and conquer all of New Guinea. If Port Moresby fell, it would give Japan control of the seas to the immediate north of Australia. Nimitz rushed the carrier USS Lexington, under Admiral Fletcher, to join USS Yorktown and an American-Australian task force, with orders to contest the Japanese advance. The resulting Battle of the Coral Sea was the first naval battle in which ships involved never sighted each other and aircraft were solely used to attack opposing forces. Although Lexington was sunk and Yorktown seriously damaged, the Japanese lost the aircraft carrier Shōhō, suffered extensive damage to Shōkaku and heavy losses to the air wing of Zuikaku (both missed the operation against Midway the following month), and saw the Moresby invasion force turn back. Even though Allied losses were heavier than Japanese, the Japanese attack on Port Moresby was thwarted and their invasion forces turned back, yielding a strategic victory for the Allies. Moreover, Japan lacked the capacity to replace losses in ships, planes and trained pilots.
Destruction of U.S. carriers was Yamamoto's main objective, and he planned an operation to lure them to battle. After Coral Sea, he had four fleet carriers operational--Sōryū, Kaga, Akagi and Hiryū--and believed Nimitz had a maximum of two - Enterprise and Hornet. Saratoga was out of action, undergoing repair after a torpedo attack, while Yorktown sailed after three days' work to repair her flight deck and make essential repairs, with civilian work crews still aboard.
A large Japanese force was sent north to attack the Aleutian Islands, off Alaska. The next stage of Yamamoto's plan called for the capture of Midway Atoll, which would give him an opportunity to destroy Nimitz's remaining carriers; afterward, it would be turned into a major airbase, giving Japan control of the central Pacific. In May, Allied codebreakers discovered his intentions. Nagumo was again in tactical command but was focused on the invasion of Midway; Yamamoto's complex plan had no provision for intervention by Nimitz before the Japanese expected him. Planned surveillance of the U.S. fleet by long range seaplane did not happen (as a result of an abortive identical operation in March), so U.S. carriers were able to proceed to a flanking position on the approaching Japanese fleet without being detected. Nagumo had 272 planes operating from his four carriers, the U.S. 348 (of which 115 were land-based).
As anticipated by U.S. commanders, the Japanese fleet arrived off Midway on June 4 and was spotted by PBY patrol aircraft . Nagumo executed a first strike against Midway, while Fletcher launched his aircraft, bound for Nagumo's carriers. At 09:20 the first U.S carrier aircraft arrived, TBD Devastator torpedo bombers from Hornet, but their attacks were poorly coordinated and ineffectual; they failed to score a single hit, and Zero fighters shot down all 15. At 09:35, 15 TBDs from Enterprise skimmed in over the water; 14 were shot down by Zeroes. Fletcher's attacks had been disorganized, yet succeeded in distracting Nagumo's defensive fighters. When U.S. dive bombers arrived, the Zeros could not offer any protection. In addition, Nagumo's four carriers had drifted out of formation, reducing the concentration of their anti-aircraft fire. His most-criticized error was twice changing his arming orders: he first held aircraft for shipping attack as a hedge against discovery of U.S. carriers, changed this based on reports an additional strike was needed against Midway, then again after sighting Yorktown, wasting time and leaving his hangar decks crowded with refueling and rearming aircraft, and ordnance stowed outside the magazines. Yamamoto's dispositions, which left Nagumo with inadequate reconnaissance to detect (and therefore attack) Fletcher before he launched, are often ignored.
When SBD Dauntlesses from Enterprise and Yorktown appeared at an altitude of 10,000 feet (3,000 m), the Zeroes at sea level were unable to respond before the bombers pushed over. They scored a small number of significant hits; Sōryū, Kaga, and Akagi all caught fire. Hiryū survived this wave of attacks and launched an attack against the American carriers which caused severe damage to Yorktown (which was later finished off by a Japanese submarine). A second attack from the U.S. carriers a few hours later found and destroyed Hiryū. Yamamoto had four additional small carriers, assigned to his scattered surface forces, all too slow to keep up with the Kido Butai and therefore never in action. Yamamoto's enormous superiority in gun power was irrelevant as the U.S. had air superiority at Midway and could refuse a surface gunfight (and, by remarkable good fortune, Spruance moved to avoid, based on a faulty submarine report); Yamamoto's flawed dispositions had made closing to engage after dark on June 4 impossible. Midway was a decisive victory for the U.S. Navy and the high point in Japanese aspirations in the Pacific.
Japanese land forces continued to advance in the Solomon Islands and New Guinea. From July 1942, a few Australian reserve battalions, many of them very young and untrained, fought a stubborn rearguard action in New Guinea, against a Japanese advance along the Kokoda Track, towards Port Moresby, over the rugged Owen Stanley Ranges. The militia, worn out and severely depleted by casualties, were relieved in late August by regular troops from the Second Australian Imperial Force, returning from action in the Mediterranean theater.
In early September 1942, Japanese marines attacked a strategic Royal Australian Air Force base at Milne Bay, near the eastern tip of New Guinea. They were beaten back by the Australian Army, which inflicted the first outright defeat on Japanese land forces since 1939.
At the same time as major battles raged in New Guinea, Allied forces identified a Japanese airfield under construction at Guadalcanal. In August, 16,000 Allied infantry—primarily US Marines—made an amphibious landing, to capture the airfield.
Japanese and Allied forces occupied various parts of the island. Over the following six months, both sides fed resources into an escalating battle of attrition on the island, at sea, and in the sky. Most of the Japanese aircraft in the South Pacific were drafted into the Japanese defence of Guadalcanal, facing Allied air forces based at Henderson Field. Japanese ground forces launched attacks on US positions around Henderson Field, suffering high casualties. These offensives were resupplied by Japanese convoys known to the Allies as the "Tokyo Express", which often faced night battles with the Allied navies, and expended destroyers IJN could ill-afford to lose. Later fleet battles involving heavier ships and even daytime carrier battles resulted in a stretch of water near Guadalcanal becoming known as "Ironbottom Sound", from the severe losses to both sides. However, only the US Navy could quickly replace and repair its losses. The Allies were victorious on Guadalcanal in February 1943.
By late 1942, the Japanese were also retreating along the Kokoda Track in the highlands of New Guinea. Australian and U.S. counteroffensives culminated in the capture of the key Japanese beachhead in eastern New Guinea, the Buna-Gona area, in early 1943.
In June 1943, the Allies launched Operation Cartwheel, which defined their offensive strategy in the South Pacific. The operation was aimed at isolating the major Japanese forward base, at Rabaul, and cutting its supply and communication lines. This prepared the way for Nimitz's island-hopping campaign towards Japan.
In the aftermath of the Japanese conquest of Burma, there was widespread disorder in eastern India, and a disastrous famine in Bengal, which ultimately caused up to 3 million deaths. In spite of these, and inadequate lines of communication, British and Indian forces attempted limited counter-attacks in Burma in early 1943. An offensive in Arakan failed, while a long distance raid mounted by the Chindits under Brigadier Orde Wingate suffered heavy losses, but was publicized to bolster Allied morale. It also provoked the Japanese to mount major offensives themselves the following year.
In August 1943, the Allies formed a new South East Asia Command (SEAC) to take over strategic responsibilities for Burma and India from the British India Command, under Wavell. In October 1943, Winston Churchill appointed Admiral Lord Louis Mountbatten as its Supreme Commander. The British and Indian Fourteenth Army was formed to face the Japanese in Burma. Under Lieutenant General William Slim, its training, morale and health greatly improved. The American General Joseph Stilwell, who also was deputy commander to Mountbatten and commanded U.S. forces in the China Burma India Theater, directed aid to China and prepared to construct the Ledo Road to link India and China by land.
On November 22, 1943, U.S. President Franklin D. Roosevelt, British Prime Minister Winston Churchill, and ROC Generalissimo Chiang Kai-shek, met in Cairo, Egypt, to discuss a strategy to defeat Japan. The meeting was also known as Cairo Conference and concluded with the Cairo Declaration.
Midway proved to be the last great naval battle for two years. The United States used the ensuing period to turn its vast industrial potential into actual ships, planes, and trained aircrew. At the same time, Japan, lacking an adequate industrial base or technological strategy, a good aircrew training program, or adequate naval resources and commerce defense, fell further and further behind. In strategic terms the Allies began a long movement across the Pacific, seizing one island base after another. Not every Japanese stronghold had to be captured; some, like Truk, Rabaul, and Formosa, were neutralized by air attack and bypassed. The goal was to get close to Japan itself, then launch massive strategic air attacks, improve the submarine blockade, and finally (only if necessary) execute an invasion.
In November 1943, U.S. Marines sustained high casualties when they overwhelmed the 4,500-strong garrison at Tarawa. This helped the Allies to improve the techniques of amphibious landings, learning from their mistakes and implementing changes such as thorough pre-emptive bombings and bombardment, more careful planning regarding tides and landing craft schedules, and better overall coordination.
The U.S. Navy did not seek out the Japanese fleet for a decisive battle, as Mahanian doctrine would suggest (and as Japan hoped); the Allied advance could only be stopped by a Japanese naval attack, which oil shortages (induced by submarine attack) made impossible.
US submarines, as well as some British and Dutch vessels, operating from bases at Cavite, in the Philippines (1941–42) Fremantle and Brisbane in Australia; Pearl Harbor; Trincomalee, Ceylon; Midway; and later Guam, played a major role in defeating Japan. This was the case even though submarines made up a small proportion of the Allied navies — less than two percent in the case of the US Navy. Submarines strangled Japan by sinking its merchant fleet, intercepting many troop transports, and cutting off nearly all the oil imports essential to weapons production and military operations. By early 1945 the oil tanks were dry. The Japanese military claimed its defenses sank 468 Allied subs. Only 42 US submarines were sunk in the Pacific, with 10 others going down in accidents or as the result of friendly fire.
US submarines accounted for 56% of the Japanese merchantmen sunk; most of the rest were destroyed by mines or aircraft. US submariners also claimed 28% of Japanese warships destroyed. Furthermore, they played important reconnaissance roles, as at the battles of the Philippine Sea and Leyte Gulf (and, coincidentally, at Midway), when they gave accurate and timely warning of the approach of the Japanese fleet. Submarines also rescued hundreds of downed fliers.
The Allied submarines did not adopt a defensive posture and wait for the enemy to attack. Within hours of Pearl Harbor, Roosevelt ordered a new doctrine into effect: unrestricted submarine warfare against Japan. This meant sinking any warship, commercial vessel, or passenger ship in Axis controlled waters, without warning and without help to survivors. Allied submarine bases were well-protected by surface fleets and aircraft.
While Japan had a large number of submarines, they did not make a significant impact on the war. In 1942, the Japanese fleet subs performed well, knocking out or damaging many Allied warships. However, Imperial Japanese Navy (and pre-war US) doctrine stipulated naval campaigns are won only by fleet battles, not guerre de course (commerce raiding). So, while the US had an unusually long supply line between its west coast and frontline areas, and was vulnerable to submarine attack, Japan's submarines were instead primarily used for long range reconnaissance and only occasionally attacked US supply lines. The Japanese submarine offensive against Australia in 1942 and 1943 also achieved little. As the war turned against Japan, IJN submarines were increasingly used to resupply strongholds which had been cut off, such as Truk and Rabaul. In addition, Japan honored its neutrality treaty with the Soviet Union and ignored US freighters shipping millions of tons of war supplies from San Francisco to Vladivostok much to the consternation of its German ally.
The US Navy, by contrast, relied on commerce raiding from the outset. However, the problem of Allied forces surrounded in the Philippines, during the early part of 1942, led to diversion of boats to "guerrilla submarine" missions. As well, basing in Australia placed boats under Japanese aerial threat while en route to patrol areas, inhibiting effectiveness, and Nimitz relied on submarines for close surveillance of enemy bases. Furthermore, the standard issue Mark 14 torpedo and its Mark VI exploder were both defective, problems not corrected until September 1943. Worst of all, before the war, an uninformed US Customs officer had seized a copy of the Japanese merchant marine code (called the "maru code" in the USN), not knowing Office of Naval Intelligence (ONI) had broken it; the Japanese government promptly changed it, and the new code was not broken again until 1943.
Thus, it was not until 1944 the US Navy began to use its 150 submarines to maximum effect: effective shipboard radar was installed, commanders lacking in aggression were replaced, and faults in torpedoes were fixed. Japanese commerce protection was "shiftless beyond description," and convoys were poorly organised and defended compared to Allied ones, a product of flawed IJN doctrine and training — errors concealed by American faults as much as Japanese overconfidence. The number of U.S. submarines patrols (and sinkings) rose steeply: 350 patrols (180 ships sunk) in 1942, 350 (335) in 1943, and 520 (603) in 1944. By 1945, sinkings had decreased because so few targets dared to move on the high seas. In all, Allied submarines destroyed 1,200 merchant ships for about five million tons of shipping. Most were small cargo carriers, but 124 were tankers bringing desperately needed oil from the East Indies. Another 320 were passenger ships and troop transports. At critical stages of the Guadalcanal, Saipan, and Leyte campaigns, thousands of Japanese troops were killed or diverted before they arrived where they were needed. Over 200 warships were sunk, ranging from many auxiliaries and destroyers to one battleship and no fewer than eight carriers. Underwater warfare was especially dangerous; of the 16,000 Americans who went out on patrol, 3,500 (22%) never returned, the highest casualty rate of any American force in World War II. The Japanese losses, 130 submarines in all, were even higher.
A single German submarine, U-862, operated in the Pacific Ocean during the war, patrolling off the Australian east coast and New Zealand in December 1944 and January 1945. It sank one ship in the Pacific before it was recalled to Batavia.
Japanese Naval and Merchant Marine losses 1941-1945 can be found here at  US Submarine claims of sunk/damaged ships 1941-1945 can be found at  The Joint Army Navy Assessment Committee has assessed US Submarine credits.
In mid-1944, Japan launched a massive invasion across China, under the code name Operation Ichi-Go. These attacks, the biggest in several years, gained much ground for Japan before they were stopped in Guangxi.
After the Allied setbacks in 1943, the South East Asia command was preparing to launch offensives into Burma on several fronts. In the first months of 1944, the Chinese and American troops of the Northern Combat Area Command, commanded by the American Joseph Stilwell, began extending the Ledo Road from India into northern Burma, while the XV Corps began an advance along the coast in the Arakan province. In February, the Japanese mounted a local counter-attack in the Arakan. After early success, this counter-attack was defeated when the Indian divisions of XV Corps stood firm, and relied on aircraft to drop supplies to isolated forward units until they could be relieved by reserve divisions.
The Japanese response to the Allied attacks was to launch an offensive of their own into India, across the mountainous and densely-forested frontier. This attack, codenamed Operation U-Go, was advocated by Lieutenant General Renya Mutaguchi, the recently promoted commander of the Japanese Fifteenth Army, and was permitted by to proceed by Imperial General Headquarters, despite misgivings at several intervening headquarters. The offensive was launched in mid-March. Although several units of the British Fourteenth Army were forced to fight their way out of encirclement, by early April they had concentrated around Imphal in Manipur state. A Japanese division which had advanced to Kohima in Nagaland cut the main road to Imphal, but failed to capture the whole of the defences at Kohima. During April, the Japanese attacks against Imphal failed, while fresh Allied formations drove the Japanese from the positions they had captured at Kohima.
As many Japanese had feared, their supply arrangements were inadequate to maintain their forces. Once Mutaguchi's hopes for an early victory were thwarted, his troops, particularly those at Kohima, starved. During May, while Mutaguchi continued to order attacks, the Allies were advancing southwards from Kohima and northwards from Imphal. The two Allied attacks met on 22 June, breaking the Japanese siege of Imphal. The Japanese finally broke off the operation on 3 July. They had lost over 50,000 troops, mainly to starvation and disease. It was the worst defeat suffered by the Japanese Army to that date.
Although the advance in the Arakan had been halted to release troops and aircraft for the Battle of Imphal, the Americans and Chinese had continued to advance in northern Burma, aided by the Chindits operating against the Japanese lines of communication. By the time campaigning ceased during the monsoon rains, the Americans had secured a vital airfield at Myitkyina, which eased the problems of the air resupply to China over The Hump.
On June 15, 1944, 535 ships began landing 128,000 U.S. Army and Marine personnel on the island of Saipan. The Allied objective was the creation of airfields within B-29 range of Tokyo. The ability to plan and execute such a complex operation in the space of 90 days was indicative of Allied logistical superiority.
It was imperative for Japanese commanders to hold Saipan. The only way to do this was to destroy the U.S. Fifth Fleet, which had 15 fleet carriers and 956 planes, 7 battleships, 28 submarines, and 69 destroyers, as well as several light and heavy cruisers. Vice Admiral Jisaburo Ozawa attacked with nine-tenths of Japan's fighting fleet, which included nine carriers with 473 planes, 5 battleships, several cruisers, and 28 destroyers. Ozawa's pilots were outnumbered 2:1 and their aircraft were becoming or were already obsolete. The Japanese had considerable antiaircraft defenses but lacked proximity fuzes or good radar. With the odds against him, Ozawa devised an appropriate strategy. His planes had greater range because they were not weighed down with protective armor; they could attack at about 480 km (300 mi) , and could search a radius of 900 km (560 mi). U.S. Navy Hellcat fighters could only attack within 200 miles (320 km) and only search within a 325-mile (523 km) radius. Ozawa planned to use this advantage by positioning his fleet 300 miles (480 km) out. The Japanese planes would hit the U.S. carriers, land at Guam to refuel, then hit the enemy again, when returning to their carriers. Ozawa also counted on about 500 land-based planes at Guam and other islands.
Admiral Raymond A. Spruance was in overall command of Fifth Fleet. The Japanese plan would have failed if the much larger U.S. fleet had closed on Ozawa and attacked aggressively; Ozawa correctly inferred Spruance would not attack. U.S. Admiral Marc Mitscher, in tactical command of Task Force 58, with its 15 carriers, was aggressive but Spruance vetoed Mitscher's plan to hunt down Ozawa because Spruance's orders made protecting the landings on Saipan his first priority.
The forces converged in the largest sea battle of World War II up to that point. Over the previous month American destroyers had destroyed 17 of 25 submarines out of Ozawa's screening force. Repeated U.S. raids destroyed the Japanese land-based planes. Ozawa's main attack lacked coordination, with the Japanese planes arriving at their targets in a staggered sequence. Following a directive from Nimitz, the U.S. carriers all had combat information centers, which interpreted the flow of radar data and radioed interception orders to the Hellcats. The result was later dubbed the Great Marianas Turkey Shoot. The few attackers to reach the U.S. fleet encountered massive AA fire with proximity fuzes. Only one American warship was slightly damaged.
On the second day, U.S. reconnaissance planes located Ozawa's fleet, 275 miles (443 km) away, and submarines sank two Japanese carriers. Mitscher launched 230 torpedo planes and dive bombers. He then discovered the enemy was actually another 60 miles (97 km) further off, out of aircraft range (based on a roundtrip flight). Mitscher decided this chance to destroy the Japanese fleet was worth the risk of aircraft losses due to running out of fuel on the return flight. Overall, the U.S. lost 130 planes and 76 aircrew; however, Japan lost 450 planes, three carriers, and 445 aircrew. The Imperial Japanese Navy's carrier force was effectively destroyed.
The Battle of Leyte Gulf was arguably the largest naval battle in history. It was a series of four distinct engagements fought off the Philippine island of Leyte from October 23 to October 26, 1944. Leyte Gulf featured the largest battleships ever built, was the last time in history that battleships engaged each other, and was also notable as the first time that kamikaze aircraft were used. Allied victory in the Philippine Sea established Allied air and sea superiority in the western Pacific. Nimitz favored blockading the Philippines and landing on Formosa. This would give the Allies control of the sea routes to Japan from southern Asia, cutting off substantial Japanese garrisons. MacArthur favoured an invasion of the Philippines, which also lay across the supply lines to Japan. Roosevelt adjudicated in favor of the Philippines. Meanwhile, Japanese Combined Fleet Chief Toyoda Soemu prepared four plans to cover all Allied offensive scenarios. On October 12, Nimitz launched a carrier raid against Formosa to make sure that planes based there could not intervene in the landings on Leyte. Soemu put Plan Sho-2 into effect, launching a series of air attacks against the U.S. carriers. However the Japanese lost 600 planes in three days, leaving them without air cover.
Sho-1 called for V. Adm. Jisaburo Ozawa's force to use an apparently vulnerable carrier force to lure the U.S. 3rd Fleet away from Leyte and remove air cover from the Allied landing forces, which would then be attacked from the west by three Japanese forces: V. Adm. Takeo Kurita's force would enter Leyte Gulf and attack the landing forces; R. Adm. Shoji Nishimura's force and V. Adm. Kiyohide Shima's force would act as mobile strike forces. The plan was likely to result in the destruction of one or more of the Japanese forces, but Toyoda justified it by saying that there would be no sense in saving the fleet and losing the Philippines.
Kurita's "Center Force" consisted of five battleships, 12 cruisers and 13 destroyers. It included the two largest battleships ever built: Yamato and Musashi. As they passed Palawan Island after midnight on October 23, the force was spotted, and U.S. submarines sank two cruisers. On October 24, as Kurita's force entered the Sibuyan Sea, USS Intrepid and USS Cabot launched 260 planes, which scored hits on several ships. A second wave of planes scored many direct hits on Musashi. A third wave, from USS Enterprise and USS Franklin hit Musashi with 11 bombs and eight torpedoes. Kurita retreated but in the evening turned around to head for San Bernardino Strait. Musashi sank at about 19:30.
Meanwhile, V. Adm. Onishi Takijiro had directed his First Air Fleet, 80 land-based planes, against U.S. carriers, whose planes were attacking airfields on Luzon. The carrier USS Princeton was hit by an armour-piercing bomb and suffered a major explosion which killed 108 crew (out of 1,569) and 80 on a cruiser which was fire-fighting alongside. Princeton sank, and the cruiser was forced to retire.
Nishimura's force consisted of two battleships, one cruiser and four destroyers. Because they were observing radio silence, Nishimura was unable to synchronise with Shima and Kurita. Nishimura and Shima had failed to even coordinate their plans before the attacks — they were long-time rivals and neither wished to have anything to do with the other. When he entered the narrow Surigao Strait at about 02:00, Shima was 22 miles (40 km) behind him, and Kurita was still in the Sibuyan Sea, several hours from the beaches at Leyte. As they passed Panaon Island, Nishimura's force ran into a trap set for them by the U.S.-Australian 7th Fleet Support Force. R. Adm. Jesse Oldendorf had six battleships, four heavy cruisers, four light cruisers, 29 destroyers and 39 PT boats. To pass the strait and reach the landings, Nishimura had to run the gauntlet. At about 03:00 the Japanese battleship Fuso and three destroyers were hit by torpedoes and Fuso broke in two. At 03:50 the U.S. battleships opened fire. Radar fire control meant they could hit targets from a much greater distance than the Japanese. The battleship Yamashiro, a cruiser and a destroyer were crippled by 16-inch (406 mm) shells; Yamashiro sank at 04:19. Only one of Nishimura's force of seven ships survived the engagement. At 04:25 Shima's force of two cruisers and eight destroyers reached the battle. Seeing Fuso and believing her to be the wrecks of two battleships, Shima ordered a retreat.
Ozawa's "Northern Force" had four aircraft carriers, two obsolete battleships partly converted to carriers, three cruisers and nine destroyers. The carriers had only 108 planes. The force was not spotted by the Allies until 16:40 on October 24. At 20:00 Soemu ordered all remaining Japanese forces to attack. Halsey saw an opportunity to destroy the remnants of the Japanese carrier force. The U.S. Third Fleet was formidable — nine large carriers, eight light carriers, six battleships, 17 cruisers, 63 destroyers and 1,000 planes — and completely outgunned Ozawa's force. Halsey's ships set out in pursuit of Ozawa just after midnight. U.S. commanders ignored reports that Kurita had turned back towards San Bernardino Strait. They had taken the bait set by Ozawa. On the morning of October 25, Ozawa launched 75 planes. Most were shot down by U.S. fighter patrols. By 08:00 U.S. fighters had destroyed the screen of Japanese fighters and were hitting ships. By evening, they had sunk the carriers Zuikaku, Zuiho, and Chiyoda, and a destroyer. The fourth carrier, Chitose and a cruiser were disabled and later sank.
Kurita passed through San Bernardino Strait at 03:00 on 25 October and headed along the coast of Samar. The only thing standing in his path were three groups (Taffy 1, 2 and 3) of the Seventh Fleet, commanded by Admiral Thomas Kinkaid. Each group had six escort carriers, with a total of more than 500 planes, and seven or eight destroyers or destroyer escorts (DE). Kinkaid still believed that Lee's force was guarding the north, so the Japanese had the element of surprise when they attacked Taffy 3 at 06:45. Kurita mistook the Taffy carriers for large fleet carriers and thought he had the whole Third Fleet in his sights. Since escort carriers stood little chance against a battleship, Adm. Clifton Sprague directed the carriers of Taffy 3 to turn and flee eastward, hoping that bad visibility would reduce the accuracy of Japanese gunfire, and used his destroyers to divert the Japanese battleships. The destroyers made harassing torpedo attacks against the Japanese. For ten minutes Yamato was caught up in evasive action. Two U.S. destroyers and a DE were sunk, but they had bought enough time for the Taffy groups to launch planes. Taffy 3 turned and fled south, with shells scoring hits on some of its carriers and sinking one of them. The superior speed of the Japanese force allowed it to draw closer and fire on the other two Taffy groups. However, at 09:20 Kurita suddenly turned and retreated north. Signals had disabused him of the notion that he was attacking the Third Fleet, and the longer Kurita continued to engage, the greater the risk of major air strikes. Destroyer attacks had broken the Japanese formations, shattering tactical control, and two of Kurita's heavy cruisers had been sunk. The Japanese retreated through the San Bernardino Strait, under continuous air attack. The Battle of Leyte Gulf was over.
The battle secured the beachheads of the U.S. Sixth Army on Leyte against attack from the sea, broke the back of Japanese naval power and opened the way for an advance to the Ryukyu Islands in 1945. The only significant Japanese naval operation afterwards was the disastrous Operation Ten-Go, in April 1945. Kurita's force had begun the battle with five battleships; when he returned to Japan, only Yamato was combat-worthy. Nishimura's sunken Yamashiro was the last battleship in history to engage another in combat.
On October 20, 1944, the U.S. Sixth Army, supported by naval and air bombardment, landed on the favorable eastern shore of Leyte, north of Mindanao. The U.S. Sixth Army continued its advance from the east, as the Japanese rushed reinforcements to the Ormoc Bay area on the western side of the island. While the Sixth Army was reinforced successfully, the U.S. Fifth Air Force was able to devastate the Japanese attempts to resupply. In torrential rains and over difficult terrain, the advance continued across Leyte and the neighboring island of Samar to the north. On December 7, U.S. Army units landed at Ormoc Bay and, after a major land and air battle, cut off the Japanese ability to reinforce and supply Leyte. Although fierce fighting continued on Leyte for months, the U.S. Army was in control.
On December 15, 1944, landings against minimal resistance were made on the southern beaches of the island of Mindoro, a key location in the planned Lingayen Gulf operations, in support of major landings scheduled on Luzon. On January 9, 1945, on the south shore of Lingayen Gulf on the western coast of Luzon, General Krueger's Sixth Army landed his first units. Almost 175,000 men followed across the twenty-mile (32 km) beachhead within a few days. With heavy air support, Army units pushed inland, taking Clark Field, 40 miles (64 km) northwest of Manila, in the last week of January.
Two more major landings followed, one to cut off the Bataan Peninsula, and another, that included a parachute drop, south of Manila. Pincers closed on the city and, on February 3, 1945, elements of the 1st Cavalry Division pushed into the northern outskirts of Manila and the 8th Cavalry passed through the northern suburbs and into the city itself.
As the advance on Manila continued from the north and the south, the Bataan Peninsula was rapidly secured. On February 16, paratroopers and amphibious units assaulted the island fortress of Corregidor, and resistance ended there on February 27.
In all, ten U.S. divisions and five independent regiments battled on Luzon, making it the largest campaign of the Pacific war, involving more troops than the United States had used in North Africa, Italy, or southern France.
Palawan Island, between Borneo and Mindoro, the fifth largest and western-most Philippine Island, was invaded on February 28, with landings of the Eighth Army at Puerto Princesa. The Japanese put up little direct defence of Palawan, but cleaning up pockets of Japanese resistance lasted until late April, as the Japanese used their common tactic of withdrawing into the mountain jungles, dispersed as small units. Throughout the Philippines, U.S. forces were aided by Filipino guerrillas to find and dispatch the holdouts.
The U.S. Eighth Army then moved on to its first landing on Mindanao (April 17), the last of the major Philippine Islands to be taken. Mindanao was followed by invasion and occupation of Panay, Cebu, Negros and several islands in the Sulu Archipelago. These islands provided bases for the U.S. Fifth and Thirteenth Air Forces to attack targets throughout the Philippines and the South China Sea.
In late 1944 and early 1945, the Allied South East Asia Command launched offensives into Burma, intending to recover most of the country, including Rangoon, the capital, before the onset of the monsoon in May.
The Indian XV Corps advanced along the coast in Arakan province, at last capturing Akyab Island after failures in the two previous years. They then landed troops behind the retreating Japanese, inflicting heavy casualties, and captured Ramree Island and Cheduba Island off the coast, establishing airfields on them which were used to support the offensive into Central Burma.
The Northern Combat Area Command resumed its advance in northern Burma, and in late January 1945, they linked up with Chinese armies attacking westwards from Yunnan province. The Ledo Road was completed, linking India and China, but too late in the war to have any significant effect.
The Japanese Burma Area Army attempted to forestall the main Allied attack on the central part of the front by withdrawing their troops behind the Irrawaddy River. Lieutenant General Heitarō Kimura, the new Japanese commander in Burma, hoped that the Allies' lines of communications would be overstretched trying to cross this obstacle. However, the advancing British Fourteenth Army under Lieutenant General William Slim switched its axis of advance to outflank the main Japanese armies.
During February, Fourteenth Army secured bridgeheads across the Irrawaddy on a broad front. On 1 March, units of IV Corps captured the supply centre of Meiktila, throwing the Japanese into disarray. While the Japanese attempted to recapture Meiktila, XXXIII Corps captured Mandalay. The Japanese armies were heavily defeated, and with the capture of Mandalay, the Burmese population and the Burma National Army which the Japanese had raised, turned against the Japanese.
During April, Fourteenth Army advanced 300 miles (480 km) south towards Rangoon, the capital and principal port of Burma, but was delayed by Japanese rearguards 40 miles (64 km) north of Rangoon at the end of the month. Slim feared that the Japanese would defend Rangoon house-to-house during the monsoon, placing his army in a disastrous supply situation, and in March he had asked that a plan to capture Rangoon by an amphibious force, Operation Dracula, which had been abandoned earlier, be reinstated. Dracula was launched on 1 May, but Rangoon was found to have been abandoned. The troops which occupied Rangoon linked up with Fourteenth Army five days later, securing the Allies' lines of communication.
The Japanese forces which had been bypassed by the Allied advances attempted to break out across the Sittang River during June and July to rejoin the Burma Area Army which had regrouped in Tenasserim in southern Burma. They suffered 10,000 casualties, half their strength.
The Allies were preparing to make amphibious landings in Malaya when word of the Japanese surrender arrived.
The Borneo Campaign of 1945 was the last major campaign in the South West Pacific Area. In a series of amphibious assaults between May 1 and July 21, the Australian I Corps, under General Leslie Morshead, attacked Japanese forces occupying the island. Allied naval and air forces, centred on the U.S. 7th Fleet under Admiral Thomas Kinkaid, the Australian First Tactical Air Force and the U.S. Thirteenth Air Force also played important roles in the campaign.
The campaign opened with a landing on the small island of Tarakan on May 1. This was followed on June 1 by simultaneous assaults in the north west, on the island of Labuan and the coast of Brunei. A week later the Australians attacked Japanese positions in North Borneo. The attention of the Allies then switched back to the central east coast, with the last major amphibious assault of World War II, at Balikpapan on July 1.
Although the campaign was criticised in Australia at the time, and in subsequent years, as pointless or a "waste" of the lives of soldiers, it did achieve a number of objectives, such as increasing the isolation of significant Japanese forces occupying the main part of the Dutch East Indies, capturing major oil supplies and freeing Allied prisoners of war, who were being held in deteriorating conditions.
Hard-fought battles on the Japanese home islands of Iwo Jima, Okinawa, and others resulted in horrific casualties on both sides but finally produced a Japanese defeat. Faced with the loss of most of their experienced pilots, the Japanese increased their use of kamikaze tactics in an attempt to create unacceptably high casualties for the Allies. The U.S. Navy proposed to force a Japanese surrender through a total naval blockade and air raids.
Towards the end of the war as the role of strategic bombing became more important, a new command for the U.S. Strategic Air Forces in the Pacific was created to oversee all U.S. strategic bombing in the hemisphere, under United States Army Air Forces General Curtis LeMay. Japanese industrial production plunged as nearly half of the built-up areas of 64 cities were destroyed by B-29 firebombing raids. On March 9, 1945 – March 10, 1945 alone, about 100,000 people were killed in a fire storm caused by an attack on Tokyo. In addition, LeMay also oversaw Operation Starvation, in which the inland waterways of Japan were extensively mined by air, which disrupted the small amount of remaining Japanese coastal sea traffic.
On August 6, 1945, the B-29 Enola Gay dropped an atomic bomb on the Japanese city of Hiroshima, in the first nuclear attack in history. On August 9, another was dropped on Nagasaki. This was the last nuclear attack. More than 240,000 people died as a direct result of these two bombings. The necessity of the atomic bombings has long been debated, with detractors claiming that a naval blockade and bombing campaign had already made invasion, hence the atomic bomb, unnecessary.
However, other scholars have argued that the bombings did obviate invasion, including a planned Soviet invasion of Hokkaidō, or a prolonged blockade and bombing campaign, any of which may have exacted even higher casualties among Japanese civilians.
On February 3, 1945, the Soviet Union agreed with Roosevelt to enter the Pacific conflict. It promised to act 90 days after the war ended in Europe and did so exactly on schedule on August 9, by invading Manchuria. A battle-hardened, one million-strong Soviet force, transferred from Europe, attacked Japanese forces in Manchuria and quickly defeated the Japanese Kantōgun (Kwantung Army group).
The effects of the "Twin Shocks"—the atomic bombing and the Soviet entry—were profound. On August 10, the "sacred decision" was made by Japanese Cabinet to accept the Potsdam terms on one condition: the "prerogative of His Majesty as a Sovereign Ruler". At noon on August 15, after the American government's intentionally ambiguous reply, stating that the "authority" of the emperor "shall be subject to" the Supreme Commander of the Allied Powers", the Emperor broadcast to the nation and to the world at large the rescript of surrender, ending the Second World War.
In Japan, August 14 is considered to be the day that the Pacific War ended. However, as Imperial Japan actually surrendered on August 15, this day became known in the English-speaking countries as "V-J Day" (Victory in Japan). The formal Instrument of Surrender was signed on September 2, 1945, on the battleship USS Missouri, in Tokyo Bay. The surrender was accepted by General Douglas MacArthur as "Supreme Commander for the Allied Powers", with representatives of several Allied nations, from a Japanese delegation led by Mamoru Shigemitsu and Yoshijiro Umezu.
Following this period, MacArthur went to Tokyo to oversee the postwar development of the country. This period in Japanese history is known as the occupation.
Before 1941 and inclusion in the Pacific War :
After inclusion in the Pacific War :
|See Atlas of Battle Fronts from July 1943 to August 1945 at Half-Month intervals|
South East Asian campaigns: 1941-12-08 – 1945-08-15
The command structures of the Pacific War varied, reflecting the different roles of various belligerent nations, and often involving different geographic scopes. These included the following: