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.