Cambodia becomes French protectorate under King Norodom

Multiple independent sources confirm that on 11 August 1863, King Norodom signed a treaty establishing a French protectorate over Cambodia, ending its tributary status to Siam. The sources agree on the date and the key terms, though some emphasize Norodom's request for protection rather than a forced cession. The Wikipedia articles on the French protectorate and Cambodia–France relations both state the date explicitly, and the Norodom article confirms the treaty's purpose.