Somdet Chaofa Prajadhipok Sakdidej (Thai: สมเด็จเจ้าฟ้าประชาธิปกศักดิเดชน์) was born on 8 November 1893 in Bangkok, Siam (now Thailand) to King Chulalongkorn and Queen Saovabha Phongsri.

In 1910 Chulalongkorn died and was succeeded by Prajadhipok's older brother (also a son of Queen Saovabha), Crown Prince Vajiravudh, who became King Rama VI.

With the outbreak of the First World War and the declaration of Siamese neutrality, King Vajiravudh ordered his younger brother to resign his British commission and return to Siam immediately, a great embarrassment to the prince, who wanted to serve with his men on the Western front.

[1] After the war in Europe ended, he attended the École Superieure de Guerre in France, returning to Siam to the Siamese military.

In an institutional innovation intended to restore confidence in the monarchy and government, Prajadhipok, in what was virtually his first act as king, announced the creation of the Supreme Council of the State of Siam.

[4]: 253 Many of the Princes of the Supreme Council felt that it was their duty to make amends for the mistakes of the previous reign, but their acts were not generally appreciated, for the government failed to communicate to the public the purpose of the policies they pursued to rectify Vajiravudh's extreme financial extravagances.

[5] Gradually these princes arrogated power to themselves, monopolising all the main ministerial positions and appointing their sons and brothers to both administrative and military posts.

[4]: 255  The king was painstaking and conscientious; he would elicit comments and suggestions from a range of experts and study them, noting the good points in each submission, but when various options were available he would seldom be able to select the best one and abandon others.

[2]: 134  This large of an assembly proved too cumbersome, and in 1927 Prajadhipok created the Committee of the Privy Council consisting of 40 members selected from the royal family or nobility.

[2]: 137 In 1926 Prajadhipok wrote a lengthy memorandum to his American adviser Francis B. Sayre titled "Problems of Siam" in which he set forth nine questions he felt were the most serious facing the nation.

[2]: 140  In 1926 he began moves to develop the concept of prachaphiban, or "municipality", which had emerged late in the fifth reign as a law regarding public health and sanitation.

Nevertheless, the idea of teaching the Siamese the concept of democracy through a measure of decentralisation of power in municipalities had become, in Prajadhipok's mind, fundamental to future policy-making.

[3]: 240 In mid-October 1931 the king returned from a trip to Canada and the US and ordered Prince Devawongse Varoprakar, the Minister of Foreign Affairs to prepare a constitution.

[2]: 149  Prajadhipok originally planned to announce the new constitution to the nation of 6 April at the opening of the Memorial Bridge to commemorate the 150th anniversary of the Chakri dynasty.

[2]: 150  These proposals met strong opposition from Prince Damrong and other royal members of the Supreme Council and despite his own misgivings that to not proceed would result in a coup against his government, the king ultimately did not make the planned announcement.

On 20 January 1932, with the country deep in depression, the king convened a "round table" meeting to discuss the many competing arguments and to agree on how to tackle the crisis.

In this speech he remarked "I myself know nothing at all about managing finances, and all I can do is listen to the opinions of others and choose the best...If I have made a mistake, I believe I really deserve to be excused by the people of Siam".

[2]: 205  The speech was widely reported and many interpreted his words not as a frank appeal for understanding and cooperation, but as a sign of weakness and proof that the system of rule of fallible autocrats should be abolished.

[8] A small group of soldiers and civil servants began secretly plotting to overthrow absolute monarchy and bring a constitutional government to the kingdom.

[4]: 262  While Prajadhipok was away at Klai Kangwon Palace in Hua Hin, the plotters took control of the Ananda Samakhom Throne Hall in Bangkok and arrested key officials (mainly princes and relatives of the king).

"[9][10] It was a significant gesture because, according to previous royal rituals, monarchs were to remain seated while their subjects made obeisance, this showed that Prajadhipok was acknowledging the changed circumstances.

Prajadhipok issued a brief statement criticising the regime that included the following phrases, since often quoted by critics of Thailand's slow political development.

I am willing to surrender the powers I formerly exercised to the people as a whole, but I am not willing to turn them over to any individual or any group to use in an autocratic manner without heeding the voice of the people.The former king had good grounds for complaint.

Due to bombing by the German Luftwaffe in 1940, the couple again moved, first to a small house in Devon, and then to Lake Vyrnwy Hotel in Powys, Wales, where the former king had a heart attack.

[14] Historian David K. Wyatt writes that Prajadhipok was "a hard-working, effective executor" who was "intellectually equal to the demands of his office", and whose main failing was to underestimate the Bangkok elite's growing nationalism, and that "[a]s late as his death in exile, many would have agreed with his judgement that a move towards democracy in 1932 was premature.

"[3]: 242  The idea that the 1932 revolution was premature is echoed in a common royalist sentiment that proliferated as the Thai monarchy regained status over ensuing decades.