102 years of Solitude and Coups in Thailand ... and counting
rank status day mon year weekday notes
1 attempt 1 Apr 1912 Wednesday Captain Yut Khongyu, chosen by lot from among 91 conspiring coupsters to assassinate King Vajiravudh, Rama 6, on 1 Apr instead betrays the coup plot. At a military tribunal 3 were sentenced to death, 20 received life imprisonment, 32 received twenty years, 6 received fifteen years, and 30 received 12 years imprisonment.
2 attempt     1917   Aborted, few details seem to exist
3 actual 24 Jun 1932 Friday The Siamese coup d'état of 1932 changed the system of government in Siam from an absolute monarchy to a constitutional monarchy. The Khana Ratsadon's (Peoples' Party's) coup ended 150 years of absolutism under the Chakri Dynasty and resulted in the first constitution of Thailand, then Siam.
4 actual 20 Jun 1933 Tuesday The first time in Thai history that the military successfully overthrew the constitutional government. The coup was led by Colonel Phraya Phahol Pholphayuhasena against the then Premier Phraya Manopakorn Nititada. The coup was in effect a counter-coup against the dictatorial policies of Phraya Mano.
5 actual 29 Jan 1939 Sunday Luang Phibunsongkhram (หลวงพิบูลสงคราม) or Phibul to purge his government of his political enemies and former rivals. Of these, 7 were released for lack of evidence, 25 were imprisoned for life, and 21 were to be executed by firing squad. However, 3 were pardoned due to their honorable records and services to the nation
6 actual 8 Nov 1947 Saturday A gang of military officers overthrows the government of Rear Admiral Thawan Thamrong Nawasawat, temporarily replacing him with Democrat Khuang Aphaiwong as nominal PM, then replacing Khuang with Field Marshall Phibunsongkhram on 8 Apr 1948.
7 attempt 1 Oct 1948 Friday Lieutenant-General Chit Mansin Sinatyotharak and Major-General Net Khemayothin, among others of the Royal Thai Army General Staff, plotted to remove Luang Phibunsongkhram but the Coup Group which had re-installed Phibun received advance notice of their plans and foiled the plot.
8 attempt 26 Feb 1949 Saturday Pridi Banomyong, forced to resign as PM on 23 August 1946 and exiled, returned to Thailand and attempted a coup against Phibun's dictatorship which failed.
9 attempt 29 Jun 1951 Friday A group of junior naval officers seized Phibun at gunpoint while he was attending the transfer ceremony of the US Navy dredge Manhattan to the Thai navy at Ratchaworadit Pier on the Chao Phraya River in Bangkok. Fighting ensued, but the naval units were heavily outnumbered by the army, police, and air forces, all loyal to Phibun.
10 actual 29 Nov 1951 Thursday A gang of military officers consolidated the rule of Phibunsongkhram and overthrew the 1949 Constitution, replacing it with King Prajadhipok's 1932 Constitution.
11 actual 17 Sep 1957 Tuesday Field Marshal Sarit Thanarat overthrows the government of Field Marshal Plaek Phibunsongkhram.
12 actual 20 Oct 1958 Monday Field Marshal Sarit Thanarat overthrows the government of General Thanom Kitticachorn
13 actual 17 Nov 1971 Wednesday Field Marshal, Admiral of the Fleet, and Marshal of the Royal Thai Air Force Thanom Kitticachorn overthrows his own government.
14 actual 6 Oct 1976 Wednesday Admiral Sangad Chaloryu overthrows the government of Seni Pramoj.
15 attempt 26 Mar 1977 Saturday A gang of young officers attempts to overthrow the appointed government of Tanin Kraivixien.
16 actual 20 Oct 1977 Thursday General Kriangsak Chomanan overthrows the appointed government of Tanin Kraivixien.
17 attempt 1-3 Apr 1981 Wednesday-Friday A group of young military officers attempts but fails to overthrow the government of General Prem Tinsulanonda.
18 attempt 9 Sep 1985 Monday Colonel Manoon Roopkachorn attempts to overthrow the government of General Prem Tinsulanonda.
19 actual 23 Feb 1991 Saturday General Sunthorn Kongsompong overthrows General Chatichai Choonhavan.
20 actual 19 Sep 2006 Tuesday General Sonthi Boonyaratglin overthrows the elected government of Thaksin Shinawatra.
21 actual 22 May 2014 Thursday General Prayuth Chan-o-cha overthrows the elected government of Yingluck Shinawatra.