The 47mm Mle 1937 (SA37 L/50) anti-tank gun was the best purpose-built anti-tank gun fielded by any army at the start of World War II if one discounts the German 88m Flak used in the anti-tank role. It could supposedly penetrate up to 72mm of armour at 1,000 metres.
It sufficiently impressed the Germans that they immediately made use of examples that fell into their hands. After the fall of France, the type was adapted into German service as the 4.7cm Pak181/182(f). In French service, a Laffly W15T six-wheeled truck was the standard tow.