During the Battle of France, in May 1940 the swiftly deteriorating situation led to an order being issued to arm all available tracked chassis and send them to the front. This included the available FT-17 hulls from which the turret had been removed to turn them into utility vehicles, the Renault ZT 4s that had not yet received their turrets, and also the Renault UE Modèle 37s produced from that moment. On 25 May the "Direction d'Infanterie" requested that Renault produce a prototype on the lines of his Chinese UEs, with a machine-gun armed superstructure. Another existing 200 vehicles were to be refitted with a simpler external MAC 31 "Reibel" machine-gun mount. It is unknown how many of both types were in fact built or modified; at least one vehicle with a superstructure is still extant.