The years 1916–17 were something of a turning-point in the development of Vietnamese nationalism. In Cochinchina an abortive attack on Saigon central prison in February 1916 was followed by a great many arrests and the virtual destruction, for the time being, of the network of secret societies which had grown up in many of the colony's provinces during the previous decade. Many members of such societies were brought before special military tribunals (justified by the fact that France was at war in Europe) and sentenced to death, exile, or long terms of imprisonment. In Annam another abortive plot, probably quite separate, was hatched at Huê in May 1916, involving the kidnapping of the boy-emperor Duy-Tân; but he was found by the French two years later, before a projected rising in the provinces of Quang-Nam and Quang-Ngai could get under way. The leader of the plot, Trân Cao Vân, was executed along with three others, and the deposed emperor was exiled to the island of Réunion.2 These events in Cochinchina and Annam brought to a halt, for a time at least, the activities of secret nationalist groups which, drawing their initial inspiration from Japan, had been increasing in strength since about 1905. In Tongking there were also secret associations, mostly acknowledging the leadership of Phan Bôi Châu who was then in exile at Canton, and strongly influenced by the revolutionary methods of Sun Yat-sen. But there also, their last important operation for several years occurred in September 1917, when Luong Ngoc Quyên escaped from prison at Thai-Nguyen and was able to control the town for a week, before being driven out and committing suicide.3 Phan Bôi Châu himself was arrested by the Chinese the following year.