Full Name 37 Kingdom of Thailand
Alliance Axis - Minor Member Nation or Possession
Entry into WW2 25 Jan 1942
Population in 1939 15,023,000
Military Deaths in WW2 5,600
Civilian Deaths in WW2 300


ww2dbaseIn 1932, after a bloodless coup, Siam became a constitutional monarchy. In 1935, King Rama VII, who had been the one to have given up absolute powers, abdicated in favor of his nephew, who would rose to the throne as King Rama VIII. In Dec 1938, General Plaek Phibunsongkhram, having just made the prime minister, began to concentrate power in his office. In early 1939, he ordered the arrest of 40 of his political opponents; 18 of them would be executed after hasty trials. In Jun 1939, he renamed his country from Siam to Prathet Thai (ie. "Thailand"), conveying a sense of importance for the Thai ethnicity, and thus rendering ethnic minorities (Malay, Chinese, Lao, Shan, and others) second-class citizens. Under Phibunsongkhram, radio and newspapers were controlled by the state. The government launched several campaigns of westernization and modernization. Abroad, Thailand befriended Japan and Germany, seeking support for Thailand's struggle against France, whose colonial administration in Indochina had repeated conflicted with Thailand in recent history.

ww2dbaseIn Sep 1940, France surrendered Indochina to Japan after two months of political intrigue and a brief military campaign. Seeing the weak responses from France and other powers, Pibulsonggram saw the opportunity to regain territory in Laos and Cambodia that Thailand had lost to the French in the early 1900s. Border skirmishes began in Oct 1940, quickly escalating to air raids on Vientiane in Laos and on Sisophon and Battambang in Cambodia; French Air Force equipment were outdated and could not adequately defend against Thai attacks. The situation turned in early 1941 with a French naval victory over Thailand. Fearing that the French forces would gain momentum, Japan interfered and negotiated a peace in which large tracts of Laotian and Cambodian territory would be turned over to Thailand. Though publicly the Thai government celebrated a victory over French Indochina, the territory it had gained amounted to only a quarter of what Phibunsongkhram had claimed was historically and rightfully Thai territory under French occupation. Phibunsongkhram began to doubt Japan's sincerity.

ww2dbaseAt 2300 hours on 7 Dec 1941, Japan demanded Thailand to grant passage to Japanese troops. Having received no response, Japanese troops forcibly crossed Thai borders on the following day, at about 1.5 hours before the attack on Pearl Harbor. Despite earlier declarations of neutrality, Phibunsongkhram knew that Thailand could not oppose Japan, and he announced that the Thai cooperation was pre-arranged. In the following days, Japan's successes through British Malaya led to Phibunsongkhram's confidence that Japan would ultimately obtain victory in the war. On 21 Dec 1941, Thailand and Japan entered into a military pact, through which the Japanese military would gain full access to Thai airfields, naval ports, and communications systems. After several British air raids against Japanese military positions in Thailand, Thailand declared war on the Allies on 25 Jan 1942.

ww2dbaseIn the United States, Thai Ambassador Seni Pramoj refused to deliver the Jan 1942 declaration of war to the United States. Ultimately, he became a leader in the Free Thai Movement supported by the United States.

ww2dbasePhibunsongkhram, who continued to advocate the expansion of Thai borders, sent troops into Burma to fight alongside the Japanese, and he was awarded by Japan with Burmese territory. His ethnic campaigns against minorities in Thailand meant that he could not accept the premise of the Greater East Asia Co-Prosperity Sphere advocated by Japan, however, leading this Phibunsongkhram's refusal to attend the namesake conference in 1943. In Jan 1943, perhaps seeing Japanese victory was not guaranteed, Thailand engaged in China in talks that ultimately saw the repatriation of many Chinese prisoners of war, who were captured by Thai troops in Burma in early 1942. In 1944, Khuang Abhaiwongse replaced Phibunsongkhram as the prime minister. Aphaiwong, ethnic Khmer, was of noble lineage. He was ostensibly friendly toward the Japanese, but in secret he had contacts with the Allies. He had secretly promised Britain the return of all Thai territorial gains in Burma and Malaya (which was treated with suspicion by Britain), and later negotiated with the United States to return territories gained from French Indochina. Seeing Japanese defenses being bolstered in Thailand in the final months of the war, he feared that fighting, and the resulting devastation, would bring suffering to Thailand. He and other anti-Japanese leaders planned for uprisings against key Japanese command positions should the Allies move into Thailand, with the goal of ending the armed conflict as quickly as possible in order to reduce the effects of war. Such actions would rely on the 90,000-strong anti-Japanese paramilitary force loyal to Aphaiwong and his allies. To Aphaiwong's relief, there would be no need for these plans to be carried out.

ww2dbaseShortly after the end of the war, Aphaiwong resigned his position as prime minister, removing himself, who could be viewed by the Allies as a collaborator, from the political scene. Meanwhile, Pridi Banomyong, a prominent politician during the 1932-1938 period and a political ally of Aphaiwong's, declared that Phibunsongkhram's declaration of war against the Allies was unconstitutional and legally void. On 17 Sep 1945, Ambassador Seni Pramoj, with US support, became the prime minister. He was succeeded by Pridi Banomyong in Mar 1946. In Jun 1946, King Rama VIII passed away, and his younger brother rose to the throne as King Rama IX. Through US support, Thailand gained a seat in the United Nations and secured US financial assistance despite having been on Japan's side during the war.

ww2dbaseSource: Wikipedia

Last Major Update: Jan 2018

Pibulsonggram, PlaekThanarat, Sarit

Events Taken Place in Thailand
Franco-Thai War1 Oct 1940 - 31 Jan 1941
Invasion of Malaya and Singapore8 Dec 1941 - 15 Feb 1942


Thai soldier with Madsen machine gun, date unknownThai Vickers 6-ton tank, date unknownRoyal Thai Air Force Ki-30 aircraft in a hangar, date unknownJapanese and Thai officers in Thailand, 1940s
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Thai soldier with Madsen machine gun, date unknown
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