The French, meanwhile, had imposed a treaty of protectorate on Annam in 1884. This treaty implied a French interest going beyond exploratory involvement in the affairs of Laos. In June 1885, the French consul general in Bangkok notified the Siamese government that a vice consulate would be established in Louangphrabang under terms of a most-favored-nation clause contained in a Franco-Siamese treaty of 1856. A new Franco-Siamese convention of May 1886 acknowledged the role of Siamese officials in Laos for the conduct of administrative matters but avoided implying French recognition of Siamese claims to sovereignty there.

Auguste Pavie arrived at Louangphrabang in 1887 to assume his post as vice consul. Pavie played a key role in saving Oun Kham's life from raiders from Lai Chau, earning the king's gratitude and a promise that he would place his kingdom under France's protection. Incidents between Siamese and French officials on the left bank, where the French had made themselves advocates of Vietnamese claims to suzerainty, continued in 1887-93. Finally, in March 1893, the French government, acceding to a campaign by the colonial lobby in Paris, decided to send three French commissioners, each with a small armed force, to evict the Siamese from outposts they had established in central and southern Laos. The commissioners had secret orders to avoid exchanges of fire if at all possible ironically, the Siamese were under identical orders from their government.

The French government dispatched two warships to the Gulf of Siam, and, in what became known as the Paknam incident, forced the passage of a fort at the mouth of the Menam River on July 12 and anchored in the river with their guns trained on the royal palace. On July 20, the French gave an ultimatum to the Siamese government to recognize the rights of Annam to the left bank territories and to meet a list of other demands within forty-eight hours. The Siamese replied on July 22, accepting the first demand in central and southern Laos but rejecting the rest. The French declared a blockade of Bangkok, whereupon the Siamese accepted the rest of the French demands. By terms of the treaty concluded on October 3, 1893, between the Government of the French Republic and the Government of His Majesty the King of Siam, Siam renounced all claims to territories on the left bank and to islands in the river.

Data as of July 1994