Cameroon 1917-05-05 registered cover sent from Duala to Paris. Postmark and registration label German.
Post of the French Empire by Illustrator, <a href="https://en.wikipedia.org/wiki/Paul_Merwart" class="extiw" title="en:Paul Merwart">Paul Merwart</a> (1855-1902) and engraver, Jules-Jacques Puyplat (1843-1915)
Self-scanned