Yaƙin Faransa na Vietnam (1858-1885) yaƙi ne mai tsawo kuma iyaka wanda aka yi yaƙi tsakanin Daular Faransa ta biyu, daga baya Jamhuriyar Faransa ta uku da daular Vietnamese ta Đại Nam a tsakiyar ƙarshen karni na 19.Ƙarshensa da sakamakonsa sun kasance nasara ga Faransawa yayin da suka ci Vietnamese da abokansuna Sinawa a 1885, hadewar Vietnam, Laos , da Cambodia , kuma a karshe ya kafa dokokin Faransanci a kan yankuna na Indochina na Faransa a kan yankin kudu maso gabashin Asiya a 1887.Wani balaguron hadin gwiwa na Franco-Spaniya ya kai hari kan Da Nang a cikin 1858 sannan suka ja da baya don mamaye Saigon.Sarki Tu Duc ya rattaba hannu kan wata yerjejeniya a watan Yunin 1862 ta baiwa Faransa ikon mallakar larduna uku a Kudu.Faransawa sun mamaye larduna uku na kudu maso yamma a cikin 1867 don kafa Cochinchina.Bayan da suka ƙarfafa ikonsu a Cochinchina, Faransawa sun mamaye sauran ƙasar Vietnam ta hanyar yaƙe-yaƙe a Tonkin, tsakanin 1873 zuwa 1886. Tonkin a wancan lokacin yana cikin wani yanayi na kusan rashin zaman lafiya, ya gangaro cikin hargitsi;kasashen Sin da Faransa sun dauki wannan yanki a matsayin wani yanki na tasiri, inda suka tura dakaru zuwa wurin.A ƙarshe dai Faransawa sun kori yawancin sojojin China daga Vietnam, amma ragowar sojojinta a wasu lardunan Vietnam sun ci gaba da yin barazana ga ikon Faransa na Tonkin.Gwamnatin Faransa ta aike da Fournier zuwa Tianjin don yin shawarwari kan yarjejeniyar Tianjin, bisa ga yadda kasar Sin ta amince da ikon Faransa kan Annam da Tonkin, tare da yin watsi da ikirarin da take yi na cin gashin kan Vietnam.Ranar 6 ga Yuni, 1884, an sanya hannu kan yarjejeniyar Huế, ta raba Vietnam zuwa yankuna uku: Tonkin, Annam, da Cochinchina, kowannensu a ƙarƙashin gwamnatoci daban-daban guda uku.Cochinchina wani yanki ne na Faransa, yayin da Tonkin da Annam suka kasance masu karewa, kuma an sanya kotun Nguyễn karkashin kulawar Faransa.