French Forces Training With US Army At Selfridge Field, Mich

The cover illustrated is from a French Bombardier training at Selfridge Army Air Filed, Mt. Clemens MI., during WWII.

II need your help; I have two questions concerning the cover:
1. Does anyone have information on: Which "Free French units"/Canada units were training at Selfridge; start/end dates?; type planes?, etc.??? and;
2. I've highlighted with a "green arrow" (upper right hand corner where stamps normally are pasted) what I think is a Military Unit-# (?) or Training Unit-# (?). I admit it ---this is a W.A.G. on my part. Does anyone know what this stands for?

THANKS for any help and assistance!
Hal

P.S. as to rate shown: The cover is overpaid 3c -- rate confusion was quite normal. 30¢ is the per-1/2-oz. International UPU Air Mail, Letter Rate for Mediterranean Africa for April 28, 1939, through October 31, 1946. 3¢ was the per-oz. Domestic, First-Class, Letter, Surface Rate. The additional 3¢ paid postage was not needed to transport the cover.

The cover was "docketed when received 2/6/45 or June 2, 45.

This doesn't answer your specific question, but I found this photo online -- it suggests that the sender, Julien Gisbert, is depicted in this photo dated March 8, 1945 (I can't read French, so I simply share the link):



http://patrice.laverdet.pagesperso-...a_volbom.htm

This helps to explain it, too:

http://www.mtclib.org/local%20history/degaulle.pdf

WT1 = THANK YOU ! That answered a lot of questions.

Best,
Hal