Prince Uthumphon, as heir designated, succeeded to the throne of Ayutthaya on the death of his father King Borommakot in May 1758 CE. His elder brother, Prince Ekathat (reign 1758-1767 CE), constantly interfered in every detail of the administration and rendered King Uthumphon's (reign 1758 CE) position insecure. After his father's cremation, King Uthumphon preferred to abdicate in favour of his elder brother, entered the monkhood and retired to Wat Pradu (1). His reign had lasted for only three months.

After the Burmese attack of 1760 CE, Uthumphon's situation became more insecure due to court intrigues, and he moved to the Palace (or its vicinity) of Jao Fa Rasami Sri Suriyawong Phong Kasatri (2), a daughter of King Borommakot and as thus his stepsister.

When Ayutthaya was conquered by the Burmese armies of King Hsinbyushin (Mangra) in 1767 CE, ex-King Uthumphon, known as Jao Fa Dok Madua (Prince Fig Flower), was taken out of his shelter, and brought to the Pho Sam Ton Camp in present Bang Pahan District (north of Ayutthaya). From here, the ex-king, together with most of the members of the royal family, hundreds of nobles and officials, and a vast number of soldiers and peasantry were taken to Ava.