I did some picking, but it was soon decided to just drape a sheet of plastic around the trees and just shake the tree and sort the resulting downpour of fruit later on. This morning, we did this with one tree (seugnettes, a kind of prune that only grows in the Lorraine). After removing the stone and most of the skins, there was still 5.5 kg of fruit-pulp left, which resulted in some 7 kg jam. And it took only fifteen minutes to shake all that off the trees!
We also had a good look around the citadel of Montmédy during one afternoon. From a distance, the outer fortifications seem like an afterthought, only added to offer some minimal added defenses. But we did the long tour and walked in the wide corridor between the outer and inner walls -- and the outer walls are still three times as high as I am. Truly an impressive fortification, too bad the houses inside the citadel walls were literally falling apart.
Now we are back home. I am looking forward to sleeping in our own bed.