Franco-Siamese Paknam incident and the cession of Laos

Background. Tensions arose from border disputes in the Mekong region, where Siamese governors expelled French merchants in 1892. In March 1893, French authorities demanded the evacuation of Siamese military posts east of the Mekong. When Siam rejected these demands, French military columns entered the disputed area in April 1893, setting the stage for the naval incident at Paknam.

Naval Incident. On 13 July 1893, French gunboats arrived at Paknam to cross the bar into the Chao Phraya River. The Siamese forbade this passage, citing the 1856 Franco-Siamese Treaty. The Siamese fort and gunboats fired warning shots, leading to a battle. The French victory resulted in a blockade of Bangkok, which harmed British trade interests significantly.

Treaty and Cession. The crisis concluded with the signing of the Franco-Siamese Treaty on 3 October 1893. Siam agreed to cede all territories east of the Mekong River to France. This cession created the territory of Laos, which was subsequently added to French Indochina, significantly expanding the colonial federation.