[7][8] Born in the United States, Bhumibol spent his early life in Switzerland, in the aftermath of the 1932 Siamese revolution, which toppled Thailand's centuries-old absolute monarchy, ruled at the time by his uncle, King Prajadhipok (Rama VII).

His US birth certificate read simply "Baby Songkla", as the parents had to consult his uncle, King Prajadhipok, then head of the House of Chakri, for an auspicious name.

[24]: 62  He briefly attended Mater Dei school in Bangkok, but in 1933 his mother took her family to Switzerland, where he continued his education at the École nouvelle de la Suisse romande in Lausanne.

[25]: 87  Three palace aides (Chit Singhaseni, But Patthamasarin, and Chaliao Pathumrot) were eventually convicted of regicide, and were executed by firing squad on 17 February 1955, after their appeals for clemency were rejected by Bhumibol.

[25]: 91–93 In December 1946, the Siamese government allocated several hundred thousand dollars for the ceremonial cremation of the remains of the late King Ananda, a necessary preliminary to the coronation of Bhumibol who was required by religious custom to light the funeral pyre.

It was in Paris that he first met Mom Rajawongse Sirikit Kitiyakara, daughter of the Thai ambassador to France (Nakkhatra Mangala) and a great-granddaughter of King Chulalongkorn and thus a cousin of Bhumibol.

In 1957, a military coup overthrew the government of Field Marshal Plaek Phibunsongkhram with allegations of lèse-majesté,[25]: 136–137 [37] corruption and manipulation of the election held earlier that year.

In August 1957, six months after parliamentary elections, General Sarit Thanarat accused the government of Field Marshal Phibunsongkhram of lèse-majesté due to its conduct of the 2,500th anniversary celebration of Buddhism.

Under Sarit, the practice of crawling in front of royalty during audiences, banned by King Chulalongkorn, was revived in certain situations and the royal-sponsored Thammayut Nikaya order was revitalised.

[50][51] Following Sarit's death General Thanom Kittikachorn rose to power to lead Thailand's military dictatorship, ultimately challenged by the 1973 Thai popular uprising.

[39]: 87  At this time, Bhumibol increasingly cultivated far-right militias and paramilitary forces, including the Red Gaurs and the Village Scouts, warning that students and political dissidents planned to bring communists to power in Thailand.

He summoned Suchinda and the leader of the pro-democracy movement, retired Major General Chamlong Srimuang, to a televised audience, and urged them to find a peaceful resolution.

[62] Weeks before the April 2006 legislative election, the Democrat Party-led opposition and the People's Alliance for Democracy petitioned Bhumibol to appoint a replacement prime minister and cabinet.

[64] In May 2006, the Sondhi Limthongkul-owned Manager Daily newspaper published a series of articles describing the "Finland Plot", alleging that Thaksin and former members of the Communist Party of Thailand planned to overthrow the king and seize control of the nation.

Events included a royal barge procession on the Chao Phraya River, fireworks displays, art exhibitions, and the pardoning of 25,000 prisoners,[70] concerts, and dance performances.

[81] On 20 April 2009, Thaksin claimed in an interview with the Financial Times that Bhumibol had been briefed by Privy Councillors Prem Tinsulanonda and Surayud Chulanont about their plans to stage the 2006 coup.

In the weeks leading up to the 2011 general election, Bhumibol appointed Air Chief Marshal Chalit Pukbhasuk, a leader of the 2006 military coup, to his privy council.

[105] Bhumibol left the hospital in July 2013,[106] and travelled to Klai Kangwon Palace at Hua Hin on 2 August 2013,[107] but returned intermittently in the following years, most recently on 1 June 2015.

[113] King Bhumibol Adulyadej died at Siriraj Hospital in Bangkok, Thailand on 13 October 2016, at 15:52 local time, at the age of 88, as announced by the royal palace later that day.

[119] Following burial, the mourning period officially ended on midnight of 30 October 2017, after which Thais resumed wearing regular colours while they awaited the future coronation of King Vajiralongkorn, which was hosted between 4–6 May 2019.

[25]: 126  The law limited the maximum land an individual could hold to 50 rai (80,000 square metres (860,000 sq ft)), at a time when the Crown Property Bureau was the kingdom's largest land-owner.

Several academics outside Thailand, including Duncan McCargo and Federico Ferrara, noted the active but indirect political involvement of Bhumibol through a "network monarchy", whose most significant proxy is Privy Council President Prem Tinsulanonda.

McCargo claimed that Bhumibol's conservative network worked behind the scenes to establish political influence in the 1990s, but was threatened by the landslide election victories of Thaksin Shinawatra in 2001 and 2005.

[127] Ferrara claimed, shortly before the Thai Supreme Court delivered its verdict to seize Thaksin Shinawatra's assets, that the judiciary was a well-established part of Bhumibol's network and represented his main avenue to exercise extra-constitutional prerogatives despite having the appearance of being constitutional.

The situation was resolved peacefully only when Police General Sant Sarutanonda told the crowd that he had received a call from royal secretary Arsa Sarasin conveying Bhumibol's request for calm.

[147] He won a gold medal for sailing in the Fourth Southeast Asian Peninsular (SEAP) Games in 1967, together with Princess Ubol Ratana whom he tied for points.

On 19 April 1966, Bhumibol also sailed the Gulf of Thailand from Hua Hin to Toey Ngam Harbour[149] in Sattahip, covering 60 nautical miles (110 km) in a 17-hour journey on the "Vega 1", an OK Class dinghy he built.

The CPB spearheaded a plan to turn Bangkok's historical Ratchadamnoen Avenue into a shopping street known as the "Champs-Élysées of Asia" and in 2007, shocked longtime residents of traditional marketplace districts by serving them with eviction notices.

The book was criticised for factual inaccuracies, disrespecting Bhumibol (it refers to him by his personal nickname "Lek"), and proposing a controversial theory explaining the mysterious death of King Ananda.

Ubol Ratana, considered Bhumibol's most intelligent and favorite child, disobeyed her parents by marrying Peter Ladd Jensen, her classmate at Massachusetts Institute of Technology.