51. March 23, 1907...

 ... is a most important Day to remember. On that day now 104 years ago the France - Siam Treaty was signed in regard to return back to France (acting as Protectorate Authority) of the Khmer provinces of Siemreap, Sisophon and Battambang. A map drafted by a mixed commission France-Siam, in compliance with the previous 104 Treaty, showing the Preah Vihear Temple is in Cambodia, is attached to the Treaty. The March 23, 1907 Treaty was later ratified by the French Parliament on June 21, 1907.  Case closed.
   It was until after World War Two and the defeat of France to the Nazis that, on September 11, 1940, Thailand asked from France for the return of their "lost territories", namely Siemreap, Sisophon and Battambang. Hostilities flared up and a cease fire was proclaimed on January 28, 1941 under the Japanese auspices. Over a month later on March 11, 1941 a Treaty of Peace between France and Thailand was signed in Tokyo confirming the return to Thailand of Battambang, Sisophon and Siemreap, except Angkor.
    When World War Two was over and the capitulation of the Japanese, France annulled the Tokyo Treaty. Negotiations continued in September 1945 in France and in April 1946 in Singapore, and concluded in Washington DC on November 17, 1946 with an Agreement annuling the previous Tokyo Treaty that was signed by France under duress.
     On December 9, 1946, one last time, Thailand returned Battambang, Sisophon and Siemreap to France for Cambodia.

Notes: These are solid bases for the borders demarcations with Thailand. But France did not do anything for Cambodia in regard to Kampuchea Krom.