Note: Chinese troops on Stuart tanks Ledo road // Chinese troops on Stuart tanks Ledo road // Surrender of American troops at Corregidor
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 and the China Burma India Theater (CBI). However these were not operational commands.
In the Pacific, 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.
Conflict between China and Japan
By 1937, Japan controlled Manchuria and was ready to move deeper into China. The Marco Polo Bridge Incident on 7 July 1937 provoked full-scale war between China and Japan. The Nationalist and Communist Chinese suspended their civil war to form a nominal alliance against Japan, and the Soviet Union quickly lent support by providing large amount of materiel to Chinese troops. In August 1937, Generalissimo Chiang Kai-shek deployed his best army to fight about 300,000 Japanese troops in Shanghai, but, after three months of fighting, Shanghai fell. The Japanese continued to push the Chinese forces back, capturing the capital Nanking in December 1937 and committed which was known as Nanking Massacre. In March 1938, Nationalist forces won their first victory at Taierzhuang. but then the city of Xuzhou was taken by the Japanese in May. In June 1938, Japan deployed about 350,000 troops to invade Wuhan and captured it in October. The Japanese achieved major military victories, but world opinion—in particular in the United States—condemned Japan, especially after the Panay incident.
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 Soviet aid to China ended as a result of the signing of the Soviet–Japanese Neutrality Pact at the beginning of its war against Nazi Germany.
In September 1940, Japan decided to cut China's only land line to the outside world by seizing Indochina, which was controlled at the time by Vichy France. Japanese forces broke their agreement with the Vichy administration and fighting broke out, ending in a Japanese victory. On 27 September Japan signed a military alliance with Germany and Italy, becoming one of the three Axis Powers. In practice, there was little coordination between Japan and Germany until 1944, by which time the U.S. was deciphering their secret diplomatic correspondence.
The war entered a new phase with the unprecedented defeat of the Japanese at Battle of Suixian–Zaoyang and 1st Battle of Changsha. After these victories, Chinese nationalist forces launched a large-scale counter-offensive in early 1940; however, due to its low military-industrial capacity, it was repulsed by Japanese army in late March 1940. In August 1940, Chinese communists launched an offensive in Central China; in retaliation, Japan instituted the "Three Alls Policy" ("Kill all, Burn all, Loot all") in occupied areas to reduce human and material resources for the communists.
By 1941 the conflict had become a stalemate. Although Japan had occupied much of northern, central, and coastal China, the Nationalist Government 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 these regimes, and of supporting several rival governments failed to make any of them a viable alternative to the Nationalist government led by Chiang Kai-shek. Conflicts between Chinese communist and nationalist forces vying for territory control behind enemy lines culminated in a major armed clash in January 1941, effectively ending their co-operation.
Japanese strategic bombing efforts mostly targeted large Chinese cities such as Shanghai, Wuhan, and Chongqing, with around 5,000 raids from February 1938 to August 1943 in the later case. Japan's strategic bombing campaigns devastated Chinese cities extensively, killing 260,000–350,934 non-combatants.
Tensions between Japan and the West
From as early as 1935 Japanese military strategists had concluded the Dutch East Indies were, because of their oil reserves, of considerable importance to Japan. By 1940 they had expanded this to include Indo-China, Malaya, and the Philippines within their concept of the Greater East Asia Co-Prosperity Sphere. Japanese troop build ups in Hainan, Taiwan, and Haiphong were noted, Japanese Army officers were openly talking about an inevitable war, and Admiral Sankichi Takahashi was reported as saying a showdown with the United States was necessary.
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 Dutch East Indies, stopped selling oil, iron ore, and steel 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.
Japan's key objective during the initial part of the conflict was to seize economic resources in the Dutch East Indies and Malaya which offered Japan a way to escape the effects of the Allied embargo. This was known as the Southern Plan. It was also decided—because of the close relationship between the UK and United States, and the belief the US would inevitably become involved—Japan would also require taking the Philippines, Wake and Guam.
Japanese planning was for fighting a limited war where Japan would seize key objectives and then establish a defensive perimeter to defeat Allied counterattacks, which in turn would lead to a negotiated peace. The attack on the US Pacific Fleet at Pearl Harbor, Hawaii, with carrier-based aircraft of the Combined Fleet was to give the Japanese time to complete a perimeter. The initial period of the war was divided into two operational phases. The First Operational Phase was further divided into three separate parts in which the major objectives of the Philippines, British Malaya, Borneo, Burma, Rabaul and the Dutch East Indies would be occupied. The Second Operational Phase called for further expansion into the South Pacific by seizing eastern New Guinea, New Britain, Fiji, Samoa, and strategic points in the Australian area. In the Central Pacific, Midway was targeted as were the Aleutian Islands in the North Pacific. Seizure of these key areas would provide defensive depth and deny the Allies staging areas from which to mount a counteroffensive.
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.
The Japanese leadership was aware that a total military victory in a traditional sense against the USA was impossible; the alternative would be negotiating for peace after their initial victories, which would recognize Japanese hegemony in Asia. 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. The Japanese leadership looked to base the conduct of the war against America on the historical experiences of the successful wars against China (1894–95) and Russia (1904–05), in both of which a strong continental power was defeated by reaching limited military objectives, not by total conquest.
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. If the United States or Britain attacked 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.
Japanese offensives, 1941–42
Following prolonged tensions between Japan and the western powers, units of the Imperial Japanese Navy and Imperial Japanese Army launched simultaneous surprise attacks on Australian, British, Dutch and US forces on 7 December (8 December in Asia/West Pacific time zones).
The locations of this first wave of Japanese attacks included: Hawaii, Malaya, Guam, Wake Island, Hong Kong, and the Philippines. Japanese forces also simultaneously invaded southern and eastern Thailand and were resisted for several hours, before the Thai government signed an armistice with Japan.
Attack on Pearl Harbor
In the early hours of 7 December (Hawaiian time), Japan launched a major surprise carrier-based air strike on Pearl Harbor without explicit warning, which crippled the U.S. Pacific Fleet, leaving eight American battleships out of action, 188 American aircraft destroyed, and 2,403 American citizens dead. At the time of the attack, the U.S. was not officially at war anywhere in the world as the Japanese embassy failed to decipher and deliver the Japanese ultimatum to the American government before noon December 7 (Washington time), which means that the people killed or property destroyed at Pearl Harbor by the Japanese attack had a non-combatant status. The Japanese had gambled that the United States, when faced with such a sudden and massive blow, would agree to a negotiated settlement and allow Japan free rein in Asia. This gamble did not pay off. American losses were less serious than initially thought: The American aircraft carriers, which would prove to be more important than battleships, were at sea, and vital naval infrastructure (fuel oil tanks, shipyard facilities, and a power station), submarine base, and signals intelligence units were unscathed. Japan's fallback strategy, relying on a war of attrition to make the U.S. come to terms, was beyond the IJN's capabilities.
Before the attack on Pearl Harbor, the 800,000-member America First Committee vehemently opposed any American intervention in the European conflict, even as America sold military aid to Britain and the Soviet Union through the Lend-Lease program. Opposition to war in the U.S. vanished after the attack. On 8 December, the United States, the United Kingdom, Canada, and the Netherlands declared war on Japan, followed by China and Australia the next day. 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 both the benefit Germany gained by Japan's distraction of the US 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.