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.

[1] Under the old concept of Thai monarchy, however, a proper king must emulate Maha Sammata in that he must be "elected by the people.

Following Isarasundhorn's coronation (posthumously known as Phutthaloetla Naphalai, or Rama II) in 1809, Prince Kshatriyanuchit (Mom Men), the surviving son of Taksin, revolted as pretender to the throne.

If there were none, then an ad hoc senabodi consisting of senior officials present at the death of a king, would elect a successor.

[5] Foreign observers accustomed to the concept of an heir apparent expected Prince Mongkut, as a son of the queen, to ascend to the throne.

However, the assembled Senabodi considered Prince Chetsadabodin a more competent choice as he had served the king in Kromma Tha for years.

He appointed his uncle, Sakdiphonlasep, viceroy on 21 July 1824 – who predeceased the king 1 May 1832, leading to yet another succession crisis.

Nangklao provided fleets and elephants and sent Siamese armies to participate in the invasion of Burma since the British promised Siam the conquered lands.

Phraya Chumporn ordered the forced migration of Mergui (a common practice in Southeast Asia regarding the newly-conquered lands),[7] which had been conquered by the British.

[8] In 1833, US President Andrew Jackson's "special agent" and envoy Edmund Roberts, referring often to Crawfurd's account,[6]: pp198ff  concluded the Siamese–American Treaty of Amity and Commerce, signed at the Royal City of Sia-Yut'hia (Bangkok) on 20 March, the last of the fourth month of the year 1194 CS (Chula Sakarat).

[9][10] Dan Beach Bradley, an American physician and prominent Western personality of the time, introduced printing and vaccination.

The three Laotian kingdoms (Lan Xang in Vientiane, Luang Prabang, and Champasak) became Siamese tributary states after Chao Phraya Maha Kshatriyaseuk (King Rama I, Nangklao's grandfather) had conquered them in 1778.

After defeating Bangkok-vassal principalities along the way, Anouvong captured Korat, the main defensive stronghold of Siam in the northeast.

Nangklao sent his uncle Maha Sakdi Polsep the Front Palace and Sing Singhaseni (at the time styled Phraya Ratchasuphawadi) to defeat the armies of Anouvong in Isan.

Dis Bunnag, the Minister of Kromma Tha, commanded a fleet to rendezvous with ground forces at Saigon.

In 1847, prompted by Emperor Thiệu Trị's treatment of Christian missionaries, French forces invaded Vietnam.

Ang Duong was installed as the Cambodian monarch under the equal patronage of both Siam and Vietnam, thus ending the war.

He was able to predict, but not live to see the neighboring kingdoms of Burma and Vietnam fall to European colonial rule.

Nangklao stipulated that the red purse money that he had earned through his business acumen should be set aside as the state's emergency fund for the future "so that Siam would be able to buy the land back" if it fell into a squabble with a foreign power.

In the reign of his nephew Chulalongkorn, Siam indeed had to pay reparations to France for the 1893 Paknam incident during the Franco-Siamese crisis, and funding in part came from Nangklao's red purse money.