112, RTGS: wikrittakan roso-roisipsong, [wí krít tàʔ kaːn rɔː sɔ̌ː rɔ́ːj sìp sɔ̌ːŋ]) was a conflict between the French Third Republic and the Kingdom of Siam.

The Siamese subsequently agreed to cede the area that constitutes most of present-day Laos to France, an act that led to the significant expansion of French Indochina.

[1] Events were brought to a head by two separate incidents when Siamese governors in Khammuan and Nong Khai expelled three French merchants from the middle Mekong in September 1892, two of them, Champenois and Esquilot, on suspicion of opium smuggling.

[1][2] Shortly afterward, the French consul in Luang Prabang, Victor-Alphonse Massie, feverish and discouraged, committed suicide on his way back to Saigon.

In March 1893, Pavie demanded that the Siamese evacuate all military posts on the east side of the Mekong River south of Khammuan, claiming that the land belonged to Vietnam.

In the south the occupation proceeded smoothly until an ambush by the Siamese on the village of Keng Kert resulted in the killing of French police inspector Grosgurin.

[4]: 18 [5] He was a member of one of the French armed columns dispatched in April 1893 by Lassenan to cross the Annamite Range into the Lao area of Khammuan (modern Thakhek)[2] and to occupy the disputed territory.

[4][5] Shortly afterward on 5 June, the Siamese commissioner organized a surprise ambush on the village of Kien Ket, where Grosgurin, confined to his sickbed, had encamped with his militia.

[1] In turn the French went one step further in July 1893 by ordering two of their ships, the sloop Inconstant and the gunboat Comète, to sail up the Chao Phraya toward Bangkok, without the permission of the Siamese.

[3] In addition, the French demanded as guarantees the temporary occupation of Chantaburi and the demilitarization of Battambang, Siem Reap and a 25-kilometer (16 mi)-wide zone on the west bank of the Mekong.

[2] Following the killing of Grosgurin, the Commissioner of the Khammuan District, Phra Yot, was acknowledged by his government to have been the responsible official, although he was initially acquitted of wrongdoing in a trial in March 1894.