He was a field marshal of the Royal Thai Army and minister of interior in the governments of military rulers Sarit Thanarat and Thanom Kittikachorn.

The new prime minister was Thanom Kittikachorn, whose son married Praphas' daughter.

During this time, Praphas was the strong man in the background who pulled the strings in the Thanom government.

He was known for obscure financial transactions and political intrigues,[1] while sitting on the boards of 44 companies.

[1] Praphas returned to Thailand in January 1977, after the military had ended the democratic interlude in October 1976.