From WW1HA president Steve Suddaby:
My research in French aerial bombing has turned up a number of references to dropping propaganada leaflets. The 1st Groupe de Bombardement (GB1) dropped leaflets in German-held areas a number of times during night raids from May to September 1917. They mentioned numbers as high as 12,000 or 16,000 leaflets dropped in a single night in addition to, say, 200 bombs. Sometimes they described it by weight — 5 kg of leaflets.
At least some of the time during this period, they were distributing statements by President Wilson.
Here’s a post about French bombers by W.I. Boucher, blogging at World War I Aviation Illustration:
This photo of a Voisin III is from the postcard collection of drakegoodman, who posts his photos on Flickr.com.