After World War One, the French military set up a program to modernize all of its weaponry, and that included a replacement for the Mle 1916 light infantry cannon. An anti-tank gun had not been necessary during the Great War, as Germany never fielded tanks in substantial numbers – but as a pioneer of the modern tank, the French recognized the need for a good AT gun. Taking a lesson from World War One, they wanted a light gun that was flexible and mobile, easily moved around the battlefield and easily concealed from enemy fire. A 25mm cartridge was specified, and both the Hotchkiss company and the Puteaux arsenal created guns to use it. Both were adopted into service, with the Hotchkiss Mle 1934 being a bit heavier and the Puteaux Mle 1937 being a bit lighter, at only about 600 pounds. The Puteaux gun was quite small, easily moved by a horse or virtually any motorized vehicle. It had a long barrel and the 25mm AP projectile had a muzzle velocity of about 3150 fps, making it quite effective on the light and medium tanks of the 1930s. It was also remarkably accurate, and the long barrel and flash hider gave it a very small firing signature. Aiming was done with either a 4x magnified optic or a set of backup iron sights.
A total of 1285 of these guns were made before the armistice of June 1940, and they served ably in the Battle of France. A few were also used by the British before Dunkirk, and after the armistice they were used by German forces in limited numbers, and also supplied to Spain and Finland as military aid (this particular one has a Finnish property tag on it).
Thanks to DriveTanks.com in Uvalde Texas for giving me access to film this Puteaux cannon for you!