Vietnam's independence was gradually eroded by France in a series of military conquests from 1859 until 1885 when the entire country became part of French Indochina. Significant political and cultural changes were placed on the Vietnamese people, including the propagation of Roman Catholicism. When Emperor Thanh Thai, who was opposed to French colonial rule, was exiled in 1907, the French decided to pass the throne to his son who was only seven years old, because they thought someone so young would be easily influenced and controlled. The boy emperor, Duy Tan, ruled as emperor of the Nguyen Dynasty from 1907 to 1916 before fleeing from Hue to resist the French.