In the late 19th century, Luang Prabang was ransacked by the Chinese Black Flag Army. France rescued King Oun Kham and added Luang Phrabang to the protectorate of French Indochina. Shortly after, the Kingdom of Champasak and the territory of Vientiane were added to the protectorate. King Sisavang Vong of Luang Phrabang became ruler of a unified Laos, and Vientiane once again became the capital. Laos never held any importance for France other than as a buffer state between Thailand and the more economically important Annam and Tonkin.