Cao Dai is the popular Vietnamese name for what began, in 1919, as a religion, but became a significant political, military, and social force between 1945 and 1955. The Cao Dai League, as a political force, allied itself with Bao Dai in 1948, and also signed an alliance with the Hoa Hao. 
It traces to a revelation in 1920, followed by the organization of a religion, CaoDaism (Dai Dao Tam Ky Pho Do), in 1926 in Vietnam. "The philosophy of CaoDaism is the essence of many religions united. Cao Dai literally means Supreme Palace or Abode on High (where God reigns). Figuratively, the word Cao Dai is used as God's symbolic name."
It was discouraged by the French, actively broken up by Ngo Dinh Diem, and apparently actively suppressed by the Communist state. As a political party, it no longer exists in the single-party Vietnamese state, but the religion itself lives on outside Vietnam.
- Patti, Archimedes L. A (1980). Why Viet Nam?: Prelude to America's Albatross. University of California Press. , pp.500-503
- History of Caodai