P.P.S.  Me yet again.  I forgot to mention, the photo of the two French marine infantrymen must, I think, date from 1884 or 1885 rather than as late as 1888.  It was taken by Edouard Hocquard, who served with the Tonkin Expeditionary Corps as a doctor in those two years.  He took part in the Bac Ninh campaign (March 1884) and the Lang Son Campaign (February 1885).  I'm pretty sure the picture, which is one of a suite of images he took in Tonkin that have been published on the internet, dates from 1884, and have said so when I used it in my Tonkin Expeditionary Corps article.  Click on the image there and it'll link you to the website.