How long did the Rattanakosin Kingdom last?
Rattanakosin Kingdom (1782–1932)
In 1776 when Tây Sơn rebel forces captured Gia Dinh they executed the entire Nguyen royal family and much of the local population. Nguyễn Ánh, the only member of the Nguyễn family still alive, managed to escape across the river to Siam. While in exile Nguyễn Ánh wished to retake Gia Dinh and push the Tay-Son rebels out.  He convinced the neutral King Phutthayotfa Chulalok of Siam to provide him with support troops and a small invasion force.