Thailand officially adopted a neutral position during World War II until the five hour-long Japanese invasion of Thailand on 8 December 1941, which led to an armistice and military alliance treaty between Thailand and the Japanese Empire in mid-December 1941. At the start of the Pacific War, the Japanese Empire pressured the Thai government to allow the passage of Japanese troops to invade British-held Malaya and Burma. After the invasion, Thailand capitulated. The Thai government under Plaek Phibunsongkhram (known simply as Phibun) considered it profitable to co-operate with the Japanese war efforts, since Thailand saw Japan – who promised to help Thailand regain some of the Indochinese territories (in today's Laos, Cambodia, and Vietnam) which had been lost to France – as an ally against Western imperialism. Following added pressure from the start of the Allied bombings of Bangkok due to the alliance with Japan, Thailand declared war on the United Kingdom and the United States and annexed territories in neighbouring countries, expanding to the north, south, and east, gaining a border with China near Kengtung.[1]
After becoming an ally of the Empire of Japan, Thailand retained control of its armed forces and internal affairs. The Japanese policy on Thailand differed from their relationship with the puppet state of Manchukuo. Japan intended bilateral relationships similar to those between Nazi Germany and Finland, Bulgaria and Romania.[2] However, Thailand at that time was labelled by both the Japanese and the Allies as the "Italy of Asia" or "Oriental Italy", a secondary power.[3][4]
Meanwhile, the Thai government had split into two factions: the Phibun regime and the Free Thai Movement, a well-organised, pro-Allied resistance movement that eventually numbered around 90,000 Thai guerrillas,[5] supported by government officials allied to the regent Pridi Banomyong. The movement was active from 1942, resisting the Phibun regime and the Japanese.[6] The partisans provided espionage services to the Allies, performed some sabotage activities, and helped engineer Phibun's downfall in 1944. After the war, Thailand returned the annexed territories but received little punishment for its wartime role under Phibun.
Thailand suffered around 5,569 military deaths during the war, almost entirely due to disease.[clarification needed] Deaths in combat included 150 in the Shan States, 180 on 8 December 1941 (the day of both the brief Japanese invasion and the failed British assault on the Ledge), and 100 during the brief Franco-Thai War.[7][8]
Thailand, formerly known as Siam, was at the time one of few independent countries in Asia. However, the country was also struggling to modernize. Under absolute monarchy, the government was plagued by incompetence. Government service was lacking, poverty was high and even government officials were plagued with glass ceilings.[9] Thai culture was rooted in the idea that the country belonged to the monarch. Absolute monarchy was only ended by a bloodless coup carried out by the People's Party on 24 June 1932, and Thailand was still struggling to set up a modern government.
The civilian government set up by the People's Party was embroiled in conflict with old conservative factions, and the new system of democracy was short lived. In April 1933, the first prime minister Phraya Manopakorn Nititada dissolved the parliament and suspended the judiciary in a coup. His government then began to adopt more monarchist and conservative policies. It was in this era that Thailand saw its first anti-communist legislation passed, which would later be used by various governments to silence political opponents. The generals of the People's Party launched a second coup in June to regain power. This new government headed by Phraya Phahon would attempt to carry out elections and follow the constitution. His government would also see a civil war that killed 17 members of the government force and an unknown amount of rebel forces. The end of this conflict saw the military promote themselves as the protector of democracy. Under the Phraya Phahon government, the parliament saw its first elected representatives, lasted its entire four-year term, and was succeeded by another elected parliament. Prime Minister Phraya Phahon left office on 13 December 1938, citing that the military should not be running the country and his health problems. He was succeeded by Field Marshal Plaek Phibunsongkhram. Under Phibun, Thailand saw a decline in democracy.
Prior to Phibun's premiership, the Thai military led by Phibun as defence minister, and the civilian liberals led by Pridi Banomyong as foreign minister, worked together harmoniously for several years, but when Phibun became prime minister in December 1938 this co-operation broke down, and military domination became more overt. His regime soon developed some fascist characteristics. In early 1939 forty political opponents, both monarchists and democrats, were arrested, and after rigged trials eighteen were executed, the first political executions in Siam in over a century. Many others, among them Prince Damrong and Phraya Songsuradej, were exiled. Phibun launched a demagogic campaign against the Chinese business class. Chinese schools and newspapers were closed, and taxes on Chinese businesses increased.[citation needed]
Phibun and Luang Wichitwathakan, the government's ideological spokesman, copied the propaganda techniques used by Hitler and Mussolini to build up the cult of the leader. Aware of the power of mass media, they used the government's monopoly on radio broadcasting to shape popular support for the regime. Popular government slogans were constantly aired on the radio and plastered on newspapers and billboards. Phibun's picture was also to be seen everywhere in society, while portraits of the ex-monarch King Prajadhipok, an outspoken critic of the autocratic regime, were banned. At the same time Phibun passed a number of authoritarian laws which gave the government the power of almost unlimited arrest and complete press censorship. During the Second World War, newspapers were instructed to print only good news emanating from Axis sources, while sarcastic comments about the internal situation were banned.[citation needed]
On 23 June 1939,[10] Phibun changed the country's name from Siam to Thai (Thai: ไทย), or Thailand, said to mean "land of the free". This was directed against the ethnic diversity in the country (Malay, Chinese, Lao, Shan, etc.) and is based on the idea of a "Thai race", a Pan-Thai nationalism whose policy is the integration of the Shan, the Lao and other Tai peoples, such as Vietnam, Burma and South China, into a "Great Kingdom of Thailand" (Thai: มหาอาณาจักรไทย)
Modernisation was also an important theme in Phibun's new Thai nationalism. From 1939 to 1942 he issued a set of twelve Cultural Mandates. In addition to requiring that all Thais salute the flag, sing the national anthem, and speak the national language, the mandates also encouraged Thais to work hard, stay informed on current events, and to dress in a Western fashion. The mandates caused performances of traditional Thai music, dance, theatre and culture to be abolished, and changed into Western style.[citation needed]
Meanwhile, all cinemas were instructed to display Phibun's picture at the end of every performance as if it were the king's portrait, and the audience were expected to rise and bow. Phibun also called himself Than phu nam (Thai: ท่านผู้นำ) ("the leader"), in a bid to create a personality cult.[citation needed]
At the start of World War II, Plaek Phibunsongkhram shared many of his countrymen's admiration of fascism and the rapid pace of national development it seemed to afford.[2] Consequently, Phibun cultivated and intensified militarism and nationalism while simultaneously building a cult of personality using modern propaganda techniques.[citation needed]
The regime also revived irredentist claims, stirring up anti-French sentiment and supporting restoration of former Thai territories in Cambodia and Laos.[11] Seeking support against France, Phibun cultivated closer relations with Japan.[11] Faced with American opposition and British hesitancy, Thailand looked to Japan for help in the confrontation with French Indochina.[12] Although the Thais were united in their demand for the return of the lost provinces, Phibun's enthusiasm for the Japanese was markedly greater than that of Pridi Banomyong, and many old conservatives as well viewed the course of the prime minister's foreign policy with misgivings.[11]
In October 1940, the Franco-Thai War broke out. The war was a sporadic battle between Thai and French forces along Thailand's eastern frontier and culminated in an invasion of Laos and Cambodia in January 1941. The Royal Thai Armed Forces were successful in occupying the disputed territories in French Indochina, with the French scoring their only notable victory at sea at the Battle of Ko Chang.
Japan used its influence with Vichy France to obtain concessions for Thailand.[11] As a result, France agreed in March 1941 to cede 54,000 square kilometres of Laotian territory west of the Mekong and most of the Cambodian province of Battambang to Thailand,[11] which reinstated the original name of Phra Tabong Province.[citation needed] The recovery of this lost territory and the regime's apparent victory over a European colonial power greatly enhanced Phibun's reputation.[11]
Because Japan wanted to maintain both its working relationship with Vichy and the status quo, the real beneficiaries of the conflict were the Japanese. They were able to expand their influence in both Thailand and Indochina. The Japanese intention was to use Thailand and Indochina as their military base to invade Burma and Malaya in the future.[citation needed]
The Thais were forced to accept only a quarter of the territory that they had lost to the French, in addition to having to pay six million piastres as a concession to the French.[2] Relations between Japan and Thailand subsequently stressed as a disappointed Phibun switched to courting the British and Americans in the hopes of warding off what he saw as an imminent Japanese invasion.[2][13][14]
After the Franco-Thai War, Phibun compromised with Pridi, and the Thai government adopted a policy of neutrality. Pridi himself sponsored production of a Thai historical drama film, The King of the White Elephant. The film carried a propaganda message from anti-war interests in Thailand: Thailand should remain neutral, only going to war to defend its sovereignty against foreign invaders.
Phibun and the Thai government were still hesitant to join the Allies or the Japanese. At 23:00 on 7 December, the Japanese presented the Thai government with an ultimatum to allow the Japanese military to enter Thailand. The Thais were given two hours to respond,[15] but the Thai government did not have any response.
On 8 December 1941, less than four hours after the attack on Pearl Harbor, Japan invaded Thailand.[11] After several hours of fighting between Thai and Japanese troops, Thailand acceded to Japanese demands for passage through the country for Japanese forces invading Burma and Malaya.[11] After the expiration of the ultimatum, the Japanese military made landings south of Bangkok and along the Kra Isthmus. After several hours of fighting, the Thai Government arranged a cease fire.[16] Phibun assured the country that the Japanese action was pre-arranged with a sympathetic Thai government.[11]
Thailand declared war on the United Kingdom and the United States on 25 January 1942.[17]
The Japanese military used Thailand, as well as north-eastern coast of Malaya as a stepping stone to invade the Malaya Peninsula. The Royal Thai Police resisted British Commonwealth forces invading Southern Thailand in December 1941 at The Battle for The Ledge, following the Japanese invasion of Malaya.[citation needed] Thailand was rewarded for Phibun's close co-operation with Japan during the early years of war with the return of further territory that had once been under Bangkok's control, namely the four northernmost Malay states after the Malayan Campaign.[11]
On 21 December 1941, a mutual offensive-defensive alliance pact between the two countries was signed.[2] The agreement, revised on 30 December, gave the Japanese full access to Thai weaponry and to Thai railways, roads, airfields, naval bases, warehouses, communications systems, and barracks. To promote greater military and economic co-operation, Pridi was removed from the cabinet and offered a seat on the politically impotent Regency Council of the absent king, which he subsequently accepted.[2] Japan meanwhile stationed 150,000 troops on Thai soil and built the famous Burma Railway through Thailand using Asian labourers and Allied prisoners of war, with more than 100,000 dying in the process.[11]
Since the Empire of Japan was using the country as a staging area for its invasions of Allied colonies in Southeast Asia, Allied planes began bombing raids on the Thai capital city of Bangkok. With this added pressure, the Phibun Government decided to declare war on the Allies.[citation needed]
The Thai government declared war on Britain and the