Hi,
According to the book "Pilotes Français sur l'Alsace et l'Allemagne",
(one second-hand here
http://www.leboncoin.fr/livres/393544474.htm)
French unit GC 1/3 "Corse" between 1500 and 1655 did a mission "armed reco" over Saverne/Sarreguemines/Sarrebourg/Haguenau/Saverne/Nancy.
About 1600 they have been engaged in a fight with three "Messerschmitt". it is not clear but ltt MArchal crashed and POW and this pilot told that he learnt that a "Messerschmitt" has been shot down (may be by ltt Deniau ?)
HTH
Bertrand