The coronation of Norodom of Cambodia in 1864 is an awkward affair at which both French and Thai representatives officiate.

Although the Thai attempt to thwart the expansion of French influence, their own influence over the monarch steadily dwindles.

In 1867 the French conclude a treaty with the Thai that give the latter control of Batdambang Province and of Siemreab Province in exchange for their renunciation of all claims of suzerainty over other parts of Cambodia.

Loss of the northwestern provinces deeply upsets Norodom, but he is beholden to the French for sending military aid to suppress a rebellion by a royal pretender.