The closing act of this struggle was the French occupation of eastern Thai territory in the Franco-Siamese war of 1893, which paved the way for an uneasy peace between Siam and France in the region for the next forty years. French Indochina's Governor-General had sent an envoy to Bangkok to bring Laos under French rule, backed by the threat of French military force. The Siamese government, mistakenly believing that they would be supported by the British, refused to concede their territories east of the Mekong River and instead reinforced their military and administrative presence there. Spurred on by the expulsion of French merchants on suspicion of opium smuggling, and the suicide of a French diplomat returning from Siam, the French took the Siamese refusal to concede its eastern territories as a "causus belli".