Outline of Vietnam
Vietnam was under Chinese control for a thousand years before becoming a nation-state in the 10th century. Successive dynasties flourished along with geographic and political expansion deeper into Southeast Asia, until it was colonized by the French in the mid-19th century. Efforts to resist the French eventually led to their expulsion from the country in the mid-20th century, leaving a nation divided politically into two countries. Bitter fighting between the two sides continued during the Vietnam War, ending with a communist victory in 1975.
France–Thailand relations
In the meantime, France was establishing a foothold in neighbouring Vietnam, putting it on a collision course with Siam. Under the orders of Napoleon III, French gunships under Rigault de Genouilly attacked the port of Da Nang in 1858, causing significant damage, and holding the city for a few months. de Gnouilly sailed south and captured the poorly defended city of Saigon in 1859. From 1859 to 1867, French troops expanded their control over all six provinces on the Mekong delta and formed a French Colony, Cochin China. In 1863, France and King Norodom of Cambodia signed a treaty of protection with France, which transferred the country from Siamese and Vietnamese overlordship to French colonial rule. A new treaty was signed between France and Siam on 15 July 1867.