The French army wore this type of uniform during the initial German invasion in the Battle of France (May 10 – June 25, 1940). It is clearly based on the Horizon Blue uniforms France used during WW1, but in brown or “khaki” cloth, as decided in 1920, and because the horizon blue stocks had been depleted (source:
https://www.worldcat.org/title/1940-linfanterie/oclc/6920279, Page 15; also cited at https://en.wikipedia.org/wiki/Horizon_blue). Jacket:
Has features of both later 1938 model (5 button front) and earlier 1920 model (rounded seams in back) (source:
Very similar cut to later
Soviet M69 HeBe.
Collar insignia patches are missing.
All buttons are marked “A.M & Cie Paris” on the back.
No markings inside.
Battle of France (May 10 – June 25, 1940):
June 7, 1940: A French courier (“estafette”) arrives at the command post of a battery of the 24e Regiment d’Artillerie Divisionnaire’s (RAD) in the Montmedy region near Meuse (Ref: 2ARME 117-B1648 ©SCA/ECPAD/Defense) Late May, 1940: -Somme: 2 Columns of Soldiers from the 7e Armée Française move towards the Weygand line (ref: 7ARMEE 60 G458 ©SCA/ECPAD/Défense). All photos above from https://www.ecpad.fr/actualites/la-bataille-de-france-10-mai-22-juin-1940-vue-du-cote-francais/.
June 4, 1940: German forces move into Dunkirk. Disarmed French soldiers file pass German officers on the outskirts of Dunkirk. The evacuation of the British Expeditionary Force had been completed a few hours earlier. (©Imperial War Museum COL 294, from https://www.iwm.org.uk/collections/item/object/205191613). 1940: French Prisoners of War, including colonial soldiers, march into German captivity (Ref: Bundesarchiv Bild 121-0427, from https://commons.wikimedia.org/wiki/File:Bundesarchiv_Bild_121-0427,_Franz%C3%B6sische_Kriegsgefangene.jpg). May 31, 1940: Evacuated French and Belgian troops on the quayside at Dover (©Imperial War Museum H 1688, from https://www.iwm.org.uk/collections/item/object/205197175). June 1, 1940: French and British troops celebrate their escape on the platform at Paddock Wood station, Kent (©Imperial War Museum H 1703, from https://www.iwm.org.uk/collections/item/object/205197182).
Some images above can be found with more analysis of the Battle of France and the Dunkirk evacuation here:
https://warwriters.com/why-france-lost-in-1940/, https://warwriters.com/the-myth-of-dunkirk-what-if-the-germans-had-not-stopped/. Free French Forces:
August 24, 1940: HM King George VI and General de Gaulle at Cove, near Aldershot, inspecting the Free French forces, who had only just escaped the German advance into France. (©Imperial War Museum H 3277, from https://www.iwm.org.uk/collections/item/object/205196772). Note MAS36 rifles but British Pattern 37 Lee-Enfield pouches.