In May 1943, the Japanese prepared
Operation Z or the Z Plan, which envisioned utilizing Japanese naval power to counter American forces threatening the outer defense perimeter line, which ran from the Aleutians down through Wake, the
Marshall and
Gilbert Islands,
Nauru, the
Bismarck Archipelago, New Guinea, and then westward past
Java and
Sumatra to Burma. In 1943–1944, Allied forces in the Solomons began driving relentlessly toward
Rabaul, eventually encircling and neutralizing the stronghold while leaving it in Japanese hands. With their position in the Solomons disintegrating, the Japanese modified the Z Plan by eliminating the Gilbert and Marshall Islands, as well as the Bismarck Archipelago, as vital areas to be defended as part of their outer perimeter. Japanese planners instead focused on the defense of a smaller inner perimeter, which included the
Marianas,
Palau,
Western New Guinea, and the Dutch East Indies. Meanwhile, in the Central Pacific, the Americans initiated a major offensive, beginning in November 1943 with landings in the Gilbert Islands. Japanese garrisons in the
Gilberts, and then the Marshalls, were methodically seized via amphibious assault. The Japanese strategy of holding overextended island garrisons had proven impossible to accomplish in practice. In February 1944, during
Operation Hailstone, the US Navy's
fast carrier task force carried out a series of large-scale air raids on the major IJN naval base at Truk. Although the Japanese had moved their major vessels out in time to avoid being caught at anchor in the atoll, two days of Allied air attacks still resulted in significant losses to Japanese aircraft and merchant shipping. The Japanese navy was forced to abandon Truk as a primary anchorage, and was now unable to effectively counter the Americans on any front along the perimeter. Consequently, the Japanese decided to husband their remaining naval strength for what they hoped would be a decisive battle at sea in the near future. Accordingly, the Japanese then developed a new plan, known as
A-GO: a decisive fleet action that would be fought somewhere from the Palaus to the
Western Carolines. It was in this area that the newly formed
Mobile Fleet, along with large numbers of land-based aircraft, would be concentrated. A-GO envisioned land-based aircraft, operating from airfields on islands in the defense perimeter, carrying out a first wave of attacks against the American fleet, wherever along the perimeter it appeared. Once the location along the perimeter of the attacking American vessels had been determined, A-GO called for the IJN's Mobile Fleet to intercept, engage and destroy it, supported by land-based airpower.
Marianas and Palaus On 12 March 1944, the US Joint Chiefs of Staff ordered the seizure of the
Northern Marianas, with a target date of 15 June. All forces for the Marianas operation—535 warships and auxiliaries together with a ground force of over 127,500 troops—were to be commanded by Admiral Raymond A. Spruance. For the Americans, securing the Marianas would disrupt the movement of Japanese airpower to and from the southern Pacific, allow for the construction of
advance naval bases closer to Japan, and provide airfields from which
B-29 bombers could reach the Japanese Home Islands. Seizing the Marianas would also offer American commanders several possible objectives for the next phase of operations, which would keep the Japanese uncertain and hinder their defensive preparations. It was also hoped that a penetration of the Japanese inner defense zone might provoke the Japanese fleet to sail out in strength for a decisive engagement, offering the opportunity to cripple the Japanese navy in a single battle. The ability to plan and execute such a complex operation in the space of 90 days was indicative of the high degree of logistical & operational superiority that Allied strategists enjoyed over their Japanese counterparts at this stage of the war. On 15 June, the 2nd and 4th Marine Divisions landed on the island of Saipan, supported by naval bombardment. However, Japanese resistance on shore was intense, and the first day's objective was not reached until D+3. Despite fanatical Japanese opposition and some desperate fighting, the Marines captured Aslito airfield on 18 June. Nafutan, Saipan's southern point, was secured on 27 June. In the north,
Mount Tapotchau, the highest point on the island, was also taken on 27 June. The Marines then steadily advanced northward. On the night of 6–7 July, three to four thousand Japanese carried out a massed banzai charge that penetrated American lines near Tanapag before being repulsed. Following this attack, hundreds of civilians on Saipan committed mass suicide, most of whom were Japanese colonists, often at the instigation of fanatical IJA troops. By 9 July, organized Japanese resistance on Saipan had ceased. The U.S. Marines reached northernmost tip of Saipan, Marpi Point, twenty-four days after the landing. Only isolated groups of hidden
Japanese holdouts remained. A month after the invasion of Saipan, the US
recaptured Guam and
captured Tinian, just south of Saipan.
Saipan and
Tinian were used extensively by the US military, as they finally placed mainland Japan within round-trip range of American B-29 bombers. Japanese air units
attacked the bases on Saipan and Tinian intermittently from November 1944 to January 1945. Until the end of the war, the
United States Army Air Forces based out of these islands conducted an
intense strategic bombing campaign against Japanese cities of military and industrial importance, including
Tokyo,
Nagoya,
Osaka, and
Kobe. The invasion of
Peleliu in the Palau Islands on 15 September was notable for a drastic change in Japanese defensive tactics, resulting in the highest casualty rate amongst US forces in an amphibious operation during the Pacific War. In a departure from the Japanese strategy in previous island battles such as Tarawa and Saipan, where defending IJA troops intensely contested the landing beaches but not the island interior, on Peleliu the Japanese constructed extensive fortifications within the ridges that dominated the center of the island. This was an example of
fukkaku, or honeycomb, tactics that Japanese island garrisons would again utilize during the battles of Iwo Jima and Okinawa in 1945.
Philippine Sea When the Americans landed on
Saipan in the Marianas, the Japanese viewed holding the island as imperative, and initiated plan A-GO. The Japanese navy deployed its largest carrier force of the war for the forthcoming battle: the nine-carrier Mobile Fleet under Vice Admiral
Jisaburō Ozawa, supplemented by 500 land-based aircraft. Facing them was the
US Fifth Fleet under Admiral
Raymond A. Spruance: 15 fleet carriers and 956 aircraft. The clash was the largest carrier battle in history. On 19 June, a series of Japanese carrier air strikes on the Fifth Fleet were shattered by strong American defenses. The lopsided engagement was later dubbed the
Great Marianas Turkey Shoot, a testament to the catastrophic losses suffered by Japanese carrier aircrew in the battle. All US carriers had
combat-information centers, which interpreted the flow of radar data and radioed interception orders to the
combat air patrols. The few Japanese planes that made it through patrolling American fighters and reached the Fifth Fleet fleet did so in a staggered sequence, only to encounter massed anti-aircraft fire with
proximity fuses. Only one American warship was slightly damaged. On the same day,
Shōkaku was hit by four torpedoes from the submarine and sank with heavy loss of life. The was also sunk by a single torpedo from the submarine . The next day, on 20 June, the Japanese carrier force was subjected to sustained American carrier air attack and suffered the loss of the carrier
Hiyō. The four Japanese carrier air strikes involved 373 aircraft, of which 130 returned. Many of these survivors were subsequently lost when
Taihō and
Shōkaku were sunk by American submarine attacks. After the second day of the battle, Japanese losses totaled three carriers and 445 aircrew, along with more than 433 carrier aircraft and around 200 land-based aircraft. The Americans lost 130 aircraft and 76 aircrew, with many due to aircraft running out of fuel returning to their carriers at night. Although the Japanese defeat at the Philippine Sea was severe in terms of the loss of the three fleet carriers, the more significant impact on Japan's war effort was the evisceration of the IJN's carrier air groups. The IJN had spent the better part of a year reconstituting its carrier air arm, and the Americans had destroyed 90% of it in two days. The Japanese had only enough pilots left to form an air group for a single light carrier. The Mobile Fleet returned home with only 35 aircraft of the 430 that it had embarked with. The battle ended in a comprehensive Japanese defeat, and virtually erased the IJN's ability to project airpower at sea.
Leyte Gulf, 1944 The loss at the Philippine Sea left the Japanese with two options: either launch an all-out offensive employing the IJN's remaining surface vessels against the next American amphibious landing, or allow the Americans to cut the
sea lanes between the Home Islands and Southeast Asia. The Japanese opted for the former, and sought to utilize their last remaining strength – the firepower of their heavy cruisers and battleships – against the American beachhead at
Leyte in the Philippine islands in October 1944. The Japanese planned to use their remaining carriers as bait to lure the American carriers away from Leyte Gulf long enough for heavy warships to enter and to destroy any American ships present. The Japanese assembled four carriers, nine battleships, 14 heavy cruisers, seven light cruisers, and 35 destroyers for this operation. These forces were split into three formations: the "Center Force", under the command of Vice Admiral
Takeo Kurita, which included the battleships and ; the "Northern Force", under the command of Ozawa, which had four carriers and two battleships partly converted to carriers, but was largely bereft of planes; and the "Southern Force", containing one group of battleships, cruisers and destroyers under the command of
Shōji Nishimura and another under
Kiyohide Shima. The Center Force would pass through the
San Bernardino Strait into the Philippine Sea, turn southwards, and then attack the transports at anchor near the American beachhead on Leyte. The Southern Force would strike at the beachhead littoral through the
Surigao Strait, while the Northern Force would lure the main American covering forces away from Leyte. Functioning as a decoy, Ozawa's carriers embarked just 108 aircraft. However, after the Center Force departed from
Brunei Bay on 23 October, two American submarines attacked it, resulting in the loss of two heavy cruisers with another crippled. After entering the
Sibuyan Sea on 24 October, Center Force was again waylaid by American carrier aircraft, forcing another heavy cruiser to retire. The Americans then sank
Musashi. Many other ships of Center Force were also attacked, but continued on. Convinced that their attacks had rendered the Center Force ineffective and that it had turned back, the American carriers sailed north to address the newly detected threat Ozawa's Northern Force and its carriers. On the night of 24–25 October, the Southern Force under Nishimura attempted to enter Leyte Gulf from the south through Surigao Strait, where an American-Australian force led by Rear Admiral
Jesse Oldendorf ambushed the Japanese. American destroyers and naval gunfire destroyed two battleships and three destroyers, with only a single Japanese destroyer surviving. As a result of observing
radio silence, Shima's group was unable to coordinate its movements with Nishimura's group and arrived at Surigao Strait at the worst possible moment, in the middle of the encounter; after making a haphazard torpedo attack, Shima retreated. Off
Cape Engaño, north of Leyte Gulf, the Americans launched over 500 aircraft sorties at the Northern Force, followed by a surface group of cruisers and destroyers. All four Japanese carriers were sunk, but the Japanese had succeeded in drawing the American carriers away from Leyte Gulf. On 25 October the final major surface action fought between the Japanese and the American fleets occurred off
Samar, when Kurita's Center Force fell upon a group of American escort carriers accompanied only by destroyers and destroyer escorts. Both sides were surprised, but the outcome looked certain, given the overwhelming advantage in firepower possessed by the Japanese. However, the Center Force conducted a largely indecisive gunnery duel before breaking off, managing only to sink several American destroyers and two escort carriers. Overall Japanese losses in the battle were extremely heavy, with four carriers, three battleships, six heavy cruisers, four light cruisers and eleven destroyers sunk. The Americans lost one light carrier, two escort carriers, two destroyers and two destroyer escorts. The Battle of Leyte Gulf was the largest naval battle of World War II and arguably the
largest naval battle in history. It was only the second time that an aircraft carrier was sunk by surface warships in the Second World War, when the Japanese Center Force sank the escort carrier
Gambier Bay off Samar. The first such occurrence being the sinking of the fleet carrier HMS Glorious off Norway in 1940. For the Japanese, the defeat at Leyte Gulf was catastrophic—its navy's greatest ever loss of ships and men in combat. The inevitable liberation of the Philippines also meant that the Japanese Home Islands would be virtually cut off from the vital resources in Japan's occupied territories across Southeast Asia.
Philippines, 1944–1945 wading ashore at Leyte On 20 October 1944 the
US Sixth Army, supported by naval and air bombardment, landed on the favorable eastern shore of Leyte, north of
Mindanao. The US Sixth Army continued its advance from the east, while the Japanese rushed reinforcements to the western side. The US reinforced the Sixth Army successfully, but the
US Fifth Air Force devastated Japanese attempts to resupply IJA troops on the island. In torrential rains and over difficult terrain, the US advance continued across Leyte and the neighboring island of Samar to the north. On 7 December US Army units landed 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 US Army was in control. On 15 December 1944, landings against minimal resistance took place 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 9 January 1945
General Krueger's Sixth Army landed its first units on the western coast of Luzon. Almost 175,000 men followed within a few days. With heavy air support, Army units pushed inland, taking
Clark Field, northwest of Manila, in the last week of January. Two more major landings followed, one to cut off the Bataan Peninsula, and another, which included a parachute drop, south of Manila. Pincers closed in on the city, and on 3 February 1945 American forces pushed into Manila proper. The month-long
battle for Manila resulted in over 100,000 civilian deaths and was the scene of the worst
urban fighting by American forces in the Pacific theater. As the advance on Manila continued from the north and the south, the Bataan Peninsula was rapidly secured. On 16 February paratroopers and amphibious units assaulted the island fortress of Corregidor, and Japanese resistance ended there on 27 February. In all, ten US divisions and five independent regiments fought on Luzon, making it the largest ground campaign of the Pacific War, involving more troops than the US had used in North Africa, Italy, or southern France. Forces included the Mexican
Escuadrón 201 fighter-squadron as part of the
Fuerza Aérea Expedicionaria Mexicana, with the squadron attached to the
58th Fighter Group of the United States Army Air Forces that flew tactical support missions. The
Eighth Army invaded
Palawan Island, between
Borneo and Mindoro (the fifth-largest and westernmost Philippine island) on 28 February 1945, with landings at
Puerto Princesa. The Japanese put up little direct defense 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,
Filipino guerrillas aided US forces to dispatch the holdouts. The US Eighth Army moved on to its first landing on Mindanao (17 April), the last of the major Philippine Islands to be taken. Then followed the invasion and occupation of
Panay,
Cebu,
Negros and several islands in the
Sulu Archipelago. These islands provided bases for the US Fifth and
Thirteenth Air Forces to attack targets throughout the Philippines and the South China Sea. ==Final stages==
Allied offensives in Burma, 1944–1945 landing at Ramree In late 1944 and early 1945, the Allied South East Asia Command launched offensives into Burma, intending to recover most of the country, including the capital of Rangoon, before the onset of the monsoon in May. The offensives were fought primarily by British Commonwealth, Chinese and American forces against Japan, assisted to some degree by Thailand, the Burma National Army and the Indian National Army. The Commonwealth land forces were drawn primarily from the United Kingdom, British India, and Africa. The Indian XV Corps (including two
West African divisions) advanced along the coast in Arakan Province, at last capturing Akyab Island. They landed troops behind the retreating Japanese, inflicting heavy casualties, and captured
Ramree Island and
Cheduba Island, establishing airfields used to support the offensive into Central Burma. The Chinese Expeditionary Force captured
Mong-Yu and Lashio, while the Chinese and American Northern Combat Area Command resumed its advance in northern Burma. In late January 1945, these two forces linked up at
Hsipaw. The Ledo Road was completed, linking India and China, but too late in the war to have any significant strategic effect on operations in China. The
Japanese Burma Area Army attempted to forestall the main Allied attack 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 switched its axis of advance to outflank the Japanese. During February, the Fourteenth Army secured bridgeheads across the Irrawaddy. On 1 March, mechanized units of
IV Corps captured the supply node of
Meiktila, throwing the Japanese defenses 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 initially created) turned against the Japanese. During April, Fourteenth Army advanced south towards Rangoon, but was delayed by Japanese rearguards to the north. Slim feared that the Japanese would defend Rangoon in house-to-house during the monsoon, which would commit his army to prolonged action with disastrously inadequate supplies, 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, only to find that the Japanese had already evacuated the city. The troops that occupied Rangoon linked up with Fourteenth Army five days later, securing the Allies' lines of communication. Japanese forces that had been bypassed by the Allied advances
attempted to break out across the Sittaung River during June and July to rejoin the Burma Area Army, which had regrouped in
Tenasserim in southern Burma. They suffered 14,000 casualties, half of their strength. Overall, the Japanese lost some 150,000 men in Burma. Only 1,700 Japanese soldiers surrendered and were taken prisoner.
Okinawa s. At Okinawa, the kamikazes caused 4,900 American deaths. The largest and bloodiest battle fought by the Americans against the Japanese took place on
Okinawa. The seizure of islands in the Ryukyus was meant to be the last step before an invasion of Japan proper. Okinawa, the largest of the Ryukyu Islands, was located from
Kyushu. The capture of Okinawa would provide airbases that could intensify aerial bombardment of Japan and offer direct land-based air support to an invasion of Kyushu. Seizing the islands would also allow the Americans to further tighten the blockade of Japan and be used as a staging area and supply base for any invasion of the Home Islands. The Japanese troops defending Okinawa, under the command of Lieutenant General
Mitsuru Ushijima, were a mixed force some 75,000–100,000 strong, augmented by thousands of conscripted civilians. American forces for the operation totaled 183,000 troops in seven divisions (four US Army and three Marine) under the
Tenth Army. The
British Pacific Fleet operated as a separate unit; its objective was to strike airfields on the chain of islands between Formosa and Okinawa, to prevent the Japanese from reinforcing Okinawa. After an intense seven-day bombardment, the main landings on Okinawa took place on 1 April 1945, on the
Hagushi beaches on the island's west coast. The Japanese did not contest the landings, and there was little opposition at the beaches, as the Japanese had decided to meet the Americans farther inland, out of range of naval gunfire. About 60,000 American troops landed on the first day, seizing two nearby airfields and pushing across the narrow width of the island. The first major Japanese counterattack occurred on 6 and 7 April, in the form of attacks by kamikaze aircraft and a naval operation, called
Ten-Go. Under the command of Admiral
Seiichi Itō, the battleship
Yamato, the light cruiser and eight destroyers sortied from Kyushu as bait, meant to draw away as many American carrier aircraft as possible from Okinawa, in order to leave Allied naval forces vulnerable to large-scale kamikaze attacks. As a consequence of crippling Japanese shortages, the
Yamato had only enough fuel to reach Okinawa. If she managed to reach the island,
Yamato was ordered to beach herself and use her guns to support Japanese forces with indirect fire. After being sighted by an American submarine and reconnaissance aircraft, the
Yamato,
Yahagi and four of the destroyers were sunk in a multi-hour blitz of aerial attacks by American carrier aircraft. Mass kamikaze attacks on American vessels near Okinawa intensified during the following three months, with 5,500 sorties being flown by the Japanese. In the northern part of Okinawa, American troops only met light opposition, and the area was captured within about two weeks. However, the main Japanese defenses were in the south. There was bitter fighting against well-entrenched Japanese troops, but US forces slowly made progress. The seizure of
Shuri castle on 29 May, the linchpin of Japanese resistance in the south, represented both a strategic and psychological blow to the remaining Japanese defenders. Organized resistance did not cease until 21 June; and many Japanese went into hiding. The campaign was not declared over until 2 July. The battle for Okinawa proved costly and lasted much longer than the Americans had expected. The Japanese skillfully utilized terrain to inflict maximum casualties upon Allied ground forces. Total American casualties were 49,451, including 12,520 dead or missing and 36,631 wounded. Japanese casualties were approximately 110,000 killed and 7,400 taken prisoner. 94% of the Japanese soldiers died, along with many civilians. Kamikaze attacks sank 36 ships, damaged 368 more and killed 4,900 US sailors, for the loss of 7,800 Japanese aircraft.
China, 1945 Despite Japanese victories in Operation Ichi-Go, Japan was losing the battle in Burma and facing constant attacks from Chinese Nationalist forces and Communist guerrillas in the countryside. The IJA began preparations for the Battle of West Hunan in March 1945, mobilizing 80,000 men to seize Chinese airfields and secure railroads in West Hunan by early April. In response, the Chinese National Military Council dispatched the 4th Front Army and the 10th and 27th Army Groups with
He Yingqin as commander-in-chief. At the same time, it airlifted the entire American-equipped Chinese New 6th Corps, along with veterans of the Burma Expeditionary Force, from
Kunming to
Zhijiang. Chinese forces totaled 110,000 men, supported by about 400 aircraft from Chinese and American air forces. Chinese forces decisively repulsed the Japanese advance, and subsequently launched a large counterattack. Concurrently, the Chinese repelled a
Japanese offensive in Henan and Hubei.
Atomic bombs On 6 August 1945, the U.S. dropped an
atomic bomb on the Japanese city of
Hiroshima in the first
nuclear attack in history. In a press release issued after the bombing, Truman warned Japan to
surrender or "expect a rain of ruin from the air, the like of which has never been seen on this Earth". On 9 August, the U.S. dropped
another atomic bomb on
Nagasaki. More than 140,000–240,000 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
incendiary bombing campaign had already made invasion, hence the atomic bomb, unnecessary. However, other scholars have argued that the atomic bombings shocked the Japanese government into surrender and helped avoid Operation Downfall, or a prolonged blockade and conventional bombing campaign, any of which would have exacted much higher casualties among Japanese civilians. attacked Japanese forces of the
Kantōgun (Kwantung Army) across most of the Manchurian frontier. The Manchurian strategic offensive operation began on 9 August 1945, with the Soviet invasion of the Japanese puppet state of Manchukuo. This was the last campaign of the Second World War, and the largest of the 1945
Soviet–Japanese War, which resumed hostilities between the USSR and Japan after almost six years of peace. Soviet forces conquered Manchukuo, Mengjiang (Inner Mongolia) and northern Korea. The USSR's entry into the war was a significant factor in the Japanese decision to surrender, as it became apparent to the government in Tokyo that the Soviets were no longer willing to act as an intermediary for a negotiated settlement on terms favorable to Japan. In late 1945, the Soviets launched a series of successful invasions of northern Japanese territories, in preparation for the possible
invasion of Hokkaido: •
Invasion of South Sakhalin (11–25 August) •
Maoka Landing (19–22 August) •
Invasion of the Kuril Islands (18 August to 1 September) •
Battle of Shumshu (18–23 August)
Surrender signs the formal
Japanese Instrument of Surrender on , 2 September 1945. Months of American air and naval attacks, two atomic bombings, and the Soviet invasion of Manchuria had a profound impact on Japanese decision-making. On 10 August 1945, Japanese Prime Minister
Kantarō Suzuki and
his cabinet decided to accept the Potsdam terms on one condition: the "prerogative of His Majesty as a Sovereign Ruler". At noon on 15 August, 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
Hirohito broadcast the rescript of surrender. In Japan, 14 August is considered the
end of the Pacific War. However, as Imperial Japan actually surrendered on 15 August, this day became known in the English-speaking countries as
V-J Day (Victory in Japan). The formal
Japanese Instrument of Surrender was signed on 2 September 1945. The surrender was accepted by MacArthur as
Supreme Commander of the Allied Powers. MacArthur then went to Tokyo to oversee the occupation of Japan (from 28 August 1945 to 28 April 1952, when the
Treaty of San Francisco came into force). ==Casualties==