When the French Navy began its heavy presence in the Mekong Delta and later colonized the southern third of Vietnam including Saigon in 1867. (dec 31, 1878 – dec 22, 1879)
Description:
https://en.wikipedia.org/wiki/Tonkin_(French_protectorate)Added to timeline:
Date:
dec 31, 1878
dec 22, 1879
~ 11 months