Rama III statue in Bangkok
Nangklao (Rama III) (full royal name Phra Nang Klao Chaoyuhua) (March 31, 1788 - April 2, 1851) third of the Chakri dynasty, was king of Thailand from 1824 to 1851.
Rama III was the last king of Siam who was a traditional monarch. His successors were traditionalists but modernized the kingdom to an extent.
During Rama III's reign, Siam became a military power. It repulsed Vietnamese invasions, and it was during his reign where Burma was defeated by the British several times. He also made inroads into Cambodia - and the country was partitioned between Vietnam and Siam. Rama III also overran Laos and ordered the destruction of Vientiane in 1827-1828.
After his death his brother Mongkut became his successor.