The Tonkin Expeditionary Corps () was an important French military command based in northern Vietnam (Tonkin) from June 1883 to April 1886. The expeditionary corps fought the Tonkin campaign (1883–6) taking part in campaigns against the Black Flag Army and the Chinese Yunnan and Guangxi Armies during the Sino-French War (August 1884–April 1885) and the period of undeclared hostilities that preceded it (August 1883–June 1884), and in important operations against Vietnamese guerilla bands during the subsequent 'Pacification of Tonkin' (May 1885–February 1886).