Phra Bat Somdet Phra Borommaracha Kasat Bowon Sucharit (), Somdet Phra Chao Yu Hua Phra Thi Nang Suriyat Amarin () or Somdet Phra Chao Ekkathat () was the 33rd and last monarch of Ayutthaya Kingdom, ruling from 1758 to 1767 prior to the fall of the kingdom. The name "Ekkathat" means the one with only one eye, for the King was believed to have lost one of his eyes. Moreover, he was called by the people at the time being that "Khun Luang Khi Ruean" (), meaning "the mangy king"; he was also believed to have been in leprosy.

Prince Ekkathat, or Kromma Khun Anurak Montri (), was a son of Borommakot. His elder brother, Prince Thammathibet, was made the Front Palace in 1732. However, Thammathibet had an affair with one of his father's concubines. Ekkathat, upon knowing this, told Boromakot about the lovers. Thammathibet was thus beaten to death in 1746. Ekkathat, who was then next in the succession line, were expected to be the Front Palace. However, Borommakot halted the appointment because of Ekkathat's incompetence. Borommakot himself claim If the prince inherits the throne, the kingdom will fall.
One year before his death, Borommakot decided to skip Ekkathat and appointted Ekkathat's younger brother, Uthumphon, as the Front Palace. In 1758, Borommakot died. Uthumphon was then crowned, and Ekkathat entered in priesthood to signify his surrender. However, two months after that, Ekkathat returned and claimed for the throne. Ekkathat settled himself in the Suriyat Amarin Palace—therefore came his name Somdet Phra Thi Nang Suriyat Amarin (Literally: the King of Suriyat Amarin Palace). The civil war ensued. He fought against his half-brothers—Kromma Khun Chit Sunthon, Kromma Muen Sunthon Thep and Kromma Muen Sep Phakdi. Ekkathat readily defeated and executed them. Uthumphon was forced to abdicate, and Ekkathat was crowned.

In 1760, Alaungpaya of Burma led his armies invading Ayutthaya. Ekkathat urged his abdicated brother, Uthumphon, to lead the battles. However, Alaungpaya died during the campaigns, postponing the death of Ayutthaya for another 7 years.

Siam under Ekkathat was in turmoil. Ayutthaya lost its control over network cities and Ekkathat was said to be indulged by the luxury of the court and concubines. The peasants went on the rebellion. In 1766, the Burmese armies again invaded Siam—through Mergui under Mahanoratha and Lanna under Neimyo Thihapate after subjugating Lanna and Laotian kingdoms. The Burmese captured various peripheral cities to cut down any supports given to Ayutthaya. Ekkathat ordered Siamese armies and fleets to counter the Burmese at Ratchaburi and Thon Buri, but was unable to drive off the Burmese. The two Burmese armies joined at Ayutthaya and laid the siege on the city. On April 7, 1767, Ayutthaya fell. The Burmese looted the city to the ground. Nearly all buildings were destroyed.

Siamese chronicles said Ekkathat died upon having been in starvation for more than ten days while concealing himself at Ban Chik Wood (), adjacent to Wat Sangkhawat (). His dead body was discovered by the Burmese. It was buried at a mound named "Khok Phra Men" (), in front of a Siamese revered temple called "Phra Wihan Phra Mongkhonlabophit" (). The Burmese chronicles, however, said that Ekkathat was shot to death while fleeing the palace. Soon after, Taksin (governor of Tak), an Ayutthaya's military tactician and strategist, eventually drove the Burmese out and founded the Kingdom of Thon Buri.

Category:1767 deathsCategory:Thai monarchsCategory:Rulers of Ayutthaya

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