The Pacific War Council as photographed on 12 October 1942. Pictured are representatives from the United States (seated), the Philippine Commonwealth
, China, the United Kingdom, Australia, Canada, the Netherlands, and New Zealand
Names for the war
In Allied countries during the war, the "Pacific War" was not usually distinguished from World War II in general, or was known simply as the War against Japan. In the United States, the term Pacific Theater was widely used, although this was a misnomer in relation to the Allied campaign in Burma, the war in China and other activities within the Southeast Asian Theater. However, the US Armed Forces considered the China-Burma-India Theater to be distinct from the Asiatic-Pacific Theater during the conflict.
Japan used the name Greater East Asia War (大東亜戦争 Dai Tō-A Sensō), as chosen by a cabinet decision on 10 December 1941, to refer to both the war with the Western Allies and the ongoing war in China. This name was released to the public on 12 December, with an explanation that it involved Asian nations achieving their independence from the Western powers through armed forces of the Greater East Asia Co-Prosperity Sphere. Japanese officials integrated what they called the Japan–China Incident (日支事変 Nisshi Jihen) into the Greater East Asia War.
During the Allied military occupation of Japan (1945–52), these Japanese terms were prohibited in official documents, although their informal usage continued, and the war became officially known as the Pacific War (太平洋戦争 Taiheiyō Sensō). In Japan, the Fifteen Years' War (十五年戦争 Jūgonen Sensō) is also used, referring to the period from the Mukden Incident of 1931 through 1945.
Political map of the Asia-Pacific region, 1939
The Axis aligned states which assisted Japan included the authoritarian government of Thailand, which formed a cautious alliance with the Japanese in 1941, when Japanese forces issued the government with an ultimatum following the Japanese invasion of Thailand. The leader of Thailand, Plaek Phibunsongkhram, became greatly enthusiastic about the alliance after decisive Japanese victories in the Malayan campaign and in 1942 sent the Phayap Army to assist the invasion of Burma, where former Thai territory that had been annexed by Britain were reoccupied (Occupied Malayan regions were similarly reintegrated into Thailand in 1943). The Allies supported and organized an underground anti-Japanese resistance group, known as the Free Thai Movement, after the Thai ambassador to the United States had refused to hand over the declaration of war. Because of this, after the surrender in 1945, the stance of the United States was that Thailand should be treated as a puppet of Japan and be considered an occupied nation rather than as an ally. This was done in contrast to the British stance towards Thailand, who had faced them in combat as they invaded British territory, and the United States had to block British efforts to impose a punitive peace.
Also involved were members of the Greater East Asia Co-Prosperity Sphere, which included the Manchukuo Imperial Army and Collaborationist Chinese Army of the Japanese puppet states of Manchukuo (consisting of most of Manchuria), and the collaborationist Wang Jingwei regime (which controlled the coastal regions of China), respectively. In the Burma campaign, other members, such as the anti-British Indian National Army of Free India and the Burma National Army of the State of Burma were active and fighting alongside their Japanese allies.
Moreover, Japan conscripted many soldiers from its colonies of Korea and Taiwan. Collaborationist security units were also formed in Hong Kong (reformed ex-colonial police), Singapore, the Philippines (also a member of the Greater East Asia Co-Prosperity Sphere), the Dutch East Indies (the PETA), British Malaya, British Borneo, former French Indochina (after the overthrow of the French regime in 1945 (the Vichy French had previously allowed the Japanese to use bases in French Indochina beginning in 1941, following an invasion) as well as Timorese militia. These units the assisted the Japanese war effort in their respective territories.
Germany and Italy both had limited involvement in the Pacific War. The German and the Italian navies operated submarines and raiding ships in the Indian and Pacific Oceans, notably the Monsun Gruppe. The Italians had access to concession territory naval bases in China which they utilized (and which was later ceded to collaborationist China by the Italian Social Republic in late 1943). After Japan's attack on Pearl Harbor and the subsequent declarations of war, both navies had access to Japanese naval facilities.
The major Allied participants were the United States and its colonies (including the Philippine Commonwealth, where a guerrilla war was waged after its conquest), China, which had already been engaged in bloody war against Japan since 1937 including both the KMT government National Revolutionary Army and CCP units, such as the guerrilla Eighth Route Army, New Fourth Army as well as smaller groups. The United Kingdom was also a major belligerent (mostly through colonial troops from the armed forces of India as well as from Burma, Malaya, Fiji, Tonga, etc., but also with large numbers of British troops). Australia, New Zealand, Canada, and the Dutch government-in-exile (as the possessor of the Dutch East Indies) were also involved, all of whom were members of the Pacific War Council.
Mexico provided some air support in the form of the 201st Fighter Squadron and Free France sent naval support in the form of Le Triomphant and later the Richelieu. From 1944 the French commando group Corps Léger d'Intervention also took part in resistance operations in Indochina. French Indochinese forces faced Japanese forces in a coup in 1945. The commando corps continued to operate after the coup until liberation. Some active pro-allied guerrillas in Asia included the Malayan Peoples' Anti-Japanese Army, the Korean Liberation Army, the Free Thai Movement and the Việt Minh.
The Soviet Union fought two short, undeclared border conflicts with Japan in 1938 and 1939, then remained neutral through the Soviet–Japanese Neutrality Pact of April 1941, until August 1945 when it (and Mongolia) joined the rest of the Allies and invaded the territory of Manchukuo, China, Inner Mongolia, the Japanese protectorate of Korea and Japanese-claimed territory such as South Sakhalin.
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. US 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 Mongolia engaged Japanese forces in Manchuria and northeast China.
The Imperial Japanese Navy did not integrate its units into permanent theater commands. The Imperial Japanese Army, which had already created the Kwantung Army to oversee its occupation of Manchukuo and the China Expeditionary Army during the Second Sino-Japanese War, created the Southern Expeditionary Army Group at the outset of its conquests of South East Asia. This headquarters controlled the bulk of the Japanese Army formations which opposed the Western Allies in the Pacific and South East Asia.