In December 1945, the young king Ananda Mahidol had returned to Siam from Europe, but in June 1946 he was found shot dead in his bed, under mysterious circumstances. Three palace servants were tried and executed for his murder, although there are significant doubts as to their guilt and the case remains both murky and a highly sensitive topic in Thailand today. The king was succeeded by his younger brother, Bhumibol Adulyadej. In August Pridi was forced to resign amid suspicion that he had been involved in the regicide. Without his leadership, the civilian government foundered, and in November 1947 the army, its confidence restored after the debacle of 1945, seized power.

The coup ousted the government of Pridi Banomyong front man, Luang Thamrong, who was replaced by Khuang Aphaiwong, royalist supporter, as Prime Minister of Thailand. The coup was led by military supreme leader, Phibun, and Phin Choonhavan and Kat Katsongkhram, allied with the royalists to regain their political power and Crown Property back from the reforms of the Siamese revolution of 1932. Pridi, in turn, was driven into exile, eventually settling in Beijing as a guest of the PRC. The influence of the People Party ended