When the Sino-French War took place, it was in a new situation of political pressure and, in particular, territorial annexation which had been carried out by the Foreign Powers from 1870 to 1880 at the expense of China and its tributary states from Burma to Korea, and from the Ryukyu Islands to the Yili area. For the first time since 1839, this development, which presaged a division of China into zones of influence, prompted China to take the initiative and use military force against imperialism when France attacked Tonkin.

Vietnam was one of China's oldest tributary states. For two…