Ramathibodi II

Chettathirat (, ), also known upon his accession to the Ayutthayan throne as Ramathibodi II (; 1472/73 – either July or 10 October 1529 ) was King of Sukhothai from 1485 and King of Ayutthaya from 1491 to 1529. His reign was marked by the first Western contact with the Portuguese.

War with Lanna In 1513, King Kaew of Lanna launched an invasion into Sukhothai. Ramathibodi II personally led the Siamese forces to repel the Lanna army and subsequently advanced into Lanna territory. In 1515, he sacked Lampang—a common Southeast Asian practice of punitive raiding without long-term occupation. Afterwards, he appointed his son, Prince Athittayawong, as King of Sukhothai.

Establishment of the Corvée system

In mainland Southeast Asia, political and military strength depended heavily on the control of manpower. In 1518, Ramathibodi II instituted the Siamese corvée system, which would remain in place until its abolition by King Chulalongkorn in 1905.

Siamese commoners—known as phrai —were subject to lifelong labour duty to the state. All men aged eighteen were registered for conscription, either for military service (phrai thaan) or for public works (phrai luang). Although often compared to modern conscription, the Siamese corvée system comprised several distinct categories and obligations. The Krom Phra Suratsawadi, a department within the royal bureaucracy, was responsible for overseeing the registration and mobilization of manpower.

Death Ramathibodi II died in July or 10 October 1529, during which a great Halley's Comet appeared as recorded in the Siamese Chronicles:

His son, Prince Athittayawong, succeeded to the throne as Borommaracha IV.

Ancestry