Rama III

Nangklao (born Thap; 31 March 1788 – 2 April 1851), also known by his posthumous regnal name Rama III, was King of Siam from 1824 to his death in 1851. During his reign, he initiated the country's first cautious engagements with the West. Siam's territory also reached its greatest extent during this period.

Nangklao was the eldest surviving son of King Rama II. His mother Sri Sulalai was one of Rama II's secondary wives. Nangklao was likely designated as heir by his father. His accession was uncontested and smoothly confirmed by the grand council. Foreign observers, however, falsely perceived him as having usurped the prior claim of his younger half-brother Prince Mongkut, who was born to Queen Sri Suriyendra and thus "legitimate" according to Western customs. Under the old concept of Thai monarchy, however, a proper king must emulate Maha Sammata in that he must be "elected by the people." Ironically, Mongkut may have later contributed to this misconception, when he feared that his own accession might be perceived by foreign observers as a usurpation.

During Nangklao's reign, the crown strengthened the tax-farming system, which became a major and more reliable source of revenue for the kingdom. The Burney Treaty (1826) further liberalized foreign trade and reduced the royal warehouse monopoly, generating substantial income for the state. For his contributions to trade and economic development, he is regarded as "the father of Thai commerce". In military affairs, Siam consolidated its regional dominance by suppressing the Laotian Rebellion (1826–1828, in what is now the Isan region) and by prevailing in the Siamese–Vietnamese War (1831–34) and the subsequent campaign in Cambodia (1841–1845).