Upon Prasat Thong's death in 1656, Prince Chai succeeded his father as King Sanpet VI.

However, it was a Thai tradition to give brothers a higher priority over sons in succession.
Prince Sudharmmaraja plotted with his nephew, Prince Narai, to bring Sanpet VI down.
After nine months of ascension, Sanpet VI was executed following a coup.
Narai and his uncle marched into the palace, and Si Suthammaracha crowned himself king.
Si Suthammaracha appointed Narai as the Uparaja, or Viceroy of the Front Palace.
However, Narai was also an ambitious prince and had requested Dutch support against his uncle.
Si Suthammaracha's rule was weak and he fell under the control of Chao Phraya Chakri, an ambitious mandarin who also wanted the throne.

In 1656, Narai and his uncle finally alienated each other.
Si Suthammaracha lusted after Narai's sister, Princess Ratcha Kanlayani.
He ordered his soldiers to surround her residence and entered the house.
The princess hid in a book chest and it was smuggled into the Front Palace, where she reunited with her brother.

Enraged at his uncle's behavior, Narai decided to take action.
He drew his support from the Persian and Japanese mercenaries that had been persecuted during his father's reign.
He was also supported by the Dutch East India Company, as well as his brothers and the Okya Sukhothai, a powerful nobleman.
On the Day of Ashura, the Persians, Japanese and Dutch stormed the palace.
The prince engaged in single combat with his uncle, until the king fled to the Rear Palace.
Si Suthammaracha was captured and was executed at Wat Khok Phraya on 26 October 1656.
Upon Prasat Thong's death in 1656, Prince Chai succeeded his father as King Sanpet VI.
However, it was a Thai tradition to give brothers a higher priority over sons in succession. Prince Sudharmmaraja plotted with his nephew, Prince Narai, to bring Sanpet VI down. After nine months of ascension, Sanpet VI was executed following a coup. Narai and his uncle marched into the palace, and Si Suthammaracha crowned himself king. Si Suthammaracha appointed Narai as the Uparaja, or Viceroy of the Front Palace. However, Narai was also an ambitious prince and had requested Dutch support against his uncle. Si Suthammaracha's rule was weak and he fell under the control of Chao Phraya Chakri, an ambitious mandarin who also wanted the throne.
In 1656, Narai and his uncle finally alienated each other. Si Suthammaracha lusted after Narai's sister, Princess Ratcha Kanlayani. He ordered his soldiers to surround her residence and entered the house. The princess hid in a book chest and it was smuggled into the Front Palace, where she reunited with her brother.
Enraged at his uncle's behavior, Narai decided to take action. He drew his support from the Persian and Japanese mercenaries that had been persecuted during his father's reign. He was also supported by the Dutch East India Company, as well as his brothers and the Okya Sukhothai, a powerful nobleman. On the Day of Ashura, the Persians, Japanese and Dutch stormed the palace. The prince engaged in single combat with his uncle, until the king fled to the Rear Palace. Si Suthammaracha was captured and was executed at Wat Khok Phraya on 26 October 1656.
Narai