The history of Thailand from 1932 to 1973 was dominated by military dictatorships which were in power for much of the period. The main personalities of the period were the dictator Plaek Phibunsongkhram, who allied the country with Japan during the Second World War, and the civilian politician Pridi Banomyong, who founded Thammasat University and was briefly prime minister after the war.

A succession of military dictators followed Pridi's ouster—Phibun again, Sarit Thanarat, then Thanom Kittikachorn—under whom traditional, authoritarian rule was combined with increasing modernisation and Westernisation under the influence of the United States. The end of the period was marked by Thanom's resignation, following an uprising by university students.

From 1939 (excluding a few months in 1946), the official name of Thailand was changed from the Kingdom of Siam to the Kingdom of Thailand, which is still the official name of Thailand today.

Siamese revolution (1932–1939)

The military came to power in the bloodless Siamese revolution of 1932, which transformed the government of Siam from an absolute to a constitutional monarchy. King Prajadhipok initially accepted this change but later abdicated due to his strained relations with the government. Upon his abdication, King Prajadhipok issued a brief statement criticising the regime. His statement included the following phrases—often quoted by critics of the slow pace of Siam's political development:

The new regime of 1932 was led by a group of colonels headed by Phraya Phahon Phonphayuhasena and Phraya Songsuradet. In December they produced Siam's first constitution. Which included a national assembly, half appointed and half indirectly elected. The people were promised that full democratic elections would be held once half the population had completed primary education—which was expected to be sometime in the 1940s. A prime minister and cabinet were appointed and a facade of constitutional rule was maintained.

Once the new government had been established and the constitution put into effect, conflict began to erupt among the members of the new ruling coalition. There were four major factions competing for power: the older conservative civilian faction led by Phraya Manopakorn Nitithada; the senior military faction led by Phraya Phahon; the junior army and navy faction led by Luang Phibunsongkhram; and the young civilian faction led by Pridi Banomyong.

The first serious conflict arose in 1933 when Pridi was given the task of drafting a new economic plan for the nation. His radical programme called for the nationalisation of large tracts of farmland as well as rapid government-directed industrialisation. It also called for the growth of higher education so that entry into the bureaucracy would not be completely dominated by royalty and the aristocracy. However, the plan was condemned immediately by most of the government factions as being communist.

Because of its attack on private property, the members of the conservative clique were the ones most alarmed by Pridi's plan. They urged the Mano government to adopt policies that would reverse the course of the "revolution". However, when Phraya Mano attempted to do this, Phibun and Phraya Phahon launched a second coup that toppled the Mano government. Phraya Pahon was made the new prime minister, and his new government excluded all of the royalists.

Civil war and abdication of Prajadhipok

A royalist reaction came in late 1933 when Prince Boworadet, a grandson of Mongkut and one-time Minister of Defence, led an armed revolt against the government. He mobilised various provincial garrisons and marched on Bangkok, capturing the Don Muang Aerodrome along the way. The prince accused the government of disrespecting the king and promoting communism, and he demanded that the government leaders resign. He had hoped that some of the garrisons in the Bangkok area would join the revolt, but they remained loyal to the government. Meanwhile, the navy declared itself neutral and left for its bases in the south. After heavy fighting in the northern outskirts of Bangkok, the royalists were finally defeated and Prince Boworadet left for exile in French Indochina.

One effect of the repression of the insurrection was the diminution of the king's prestige. After the revolt started, King Prajadhipok declared in a telegram that he regretted the strife and civil disturbances. It is not clear whether he was motivated by a fear of being captured by rebels, a fear of being viewed as a supporter of the rebels, or a wish to avoid further choices between Phahon and Boworadet. Either way, the fact remains that at the height of the conflict, the royal couple took refuge at Songkhla. The king's withdrawal from the scene of the fighting was interpreted by the victorious party as a sign that he had failed in his duty. By refusing to give his full support to the legitimate government, his credibility was undermined.

A few months later in 1934, King Prajadhipok, whose relations with the new government had been deteriorating for some time, went abroad to receive medical treatment. While abroad, he carried on a correspondence with the government that discussed the terms under which he would continue to serve as a constitutional monarch. He requested the continuation of some traditional royal prerogatives. The government, however, would not agree.

In his abdication speech, Prajadhipok accused the government of having no regard for democratic principles, employing methods of administration incompatible with individual freedom and the principles of justice, ruling in an autocratic manner and not letting the people have a real voice in Siam's affairs. In 1934, the Press Act came into effect, forbidding the publication of any material deemed to be detrimental to the public order or to undermine morals. The law has been strictly enforced to the present day.

Reaction to the abdication was muted. Everybody was afraid of what might happen next. The government refrained from challenging any assertions in the king's abdication statement for fear of arousing further controversy. Opponents of the government kept quiet after the failure of the royalist rebellion.

Having defeated the royalists, the government now was put to the test of living up to the promises on which it had come to power. It took much more aggressive steps to carry out some important reforms. The currency went off the gold standard, allowing trade to recover. Expenditures on education were increased four-fold, thereby significantly raising the literacy rate. Elected local and provincial governments were introduced, and in November 1937 democratic development was brought forward when direct elections were held for the national assembly, although political parties were still not allowed. Thammasat University was founded, at Pridi's initiative, as a more accessible alternative to the elitist Chulalongkorn University. Military expenditure was also greatly expanded, a clear indication of the increasing influence of the military. In the years between 1934 and 1940 the kingdom's army, navy, and air force were equipped as never before.

Accession of King Ananda Mahidol After King Prajadhipok left Siam and abdicated the following year, The government then chose Prince Ananda Mahidol, who was at that time in school in Switzerland, as the next king, becoming King Rama VIII. For the first time in history, Siam was without a resident monarch and was to remain so for the next fifteen years, the Khana Ratsadon believing that he would be more pliable than Prajadhipok.

From Siam to Thailand (1939–1946) Rise of Phibunsongkhram

The military, now led by Major General Phibun as defence minister, and the civilian liberals led by Pridi 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. Phibun was an admirer of Benito Mussolini, and 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 Rajanubhab 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.

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.

Fascist Thailand On 23 June 1939,Thailand (Siam) History , CSMngt-Thai. Phibun changed the country's name from Siam to Prathet Thai (), or Thailand, said to mean "land of the free". This was a nationalist gesture: it implied the unity of all the Tai-speaking peoples, including the Lao and the Shan, but excluding the Chinese. The regime's slogan became "Thailand for the Thai."

Cultural revolution

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, know 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. By 1941 it became illegal, among other things, to ridicule those who attempted to promote national customs. The programme also encompassed fine arts. Fiercely nationalistic plays and films were sponsored by the government. Often these depicted a glorious past when Thai warriors fearlessly gained freedom for the country, defended their honour, or sacrificed themselves. Patriotism was taught in schools and was a recurrent theme in songs and dances.

At the same time, Phibun worked rigorously to rid society of its royalist influences. Traditional royal holidays were replaced with new national events and royal and aristocratic titles were abandoned. Ironically, he retained his aristocratic surname. Even the Sangha was affected when the status of the royally sponsored Thammayuth sect was downgraded.

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. Another aspect of Phibun's growing personality cult was becoming apparent in official décor. He was born in the year of the cock, and this symbol began to replace the wheel. Similarly, Phibun's auspicious birth-colour, green, was used in official decorations.

Franco-Thai War