appropriately found at the World War I museum in Kansas City Missouri
the classic French Model 1897 75mm
it was truly one of a kind, a state secret and a " game changer "
" , . . Development of the Model 1897 began as part of the ongoing artillery arms race in the late 1800s. Improvements in explosives and metallurgy made it possible create more powerful cannons than ever before, but one problem plagued designers—recoil. . . Deport’s specification called for a weapon of 75mm caliber, but the heart of the new weapon would be the recoil system. Beneath the gun’s barrel lay a cradle that held two hydraulic cylinders. The top cylinder held hydraulic fluid, while the bottom held compressed gas. A port connected the two cylinders and a floating piston kept the gas and liquid apart. When the gun fired, the fluid was forced down through the port into the second cylinder, compressing the gas until the recoil energy was expended, at which point the gas pushed against the floating piston and forced the fluid back into the first cylinder. This “counterrecoil” pushed the gun back into firing position, ready for the next shot. The system worked so smoothly that the gun essentially stayed in place after firing without jumping, eliminating the need to re-aim it before firing again. This increased the rate of fire dramatically. . . . After World War II, the French 75 was quickly retired from most European armies, although some soldiered on in the Third World. Over its long service, the Model 1897 saw action in both of the great conflagrations of the 20th century. At its introduction, the 75 represented a huge leap ahead in artillery technology, heralding in a new era of fast-firing, deadly cannons. By 1945, the weapon had been eclipsed by new designs, but the 75 remains perhaps the quintessential Allied artillery piece of World War I."
Military Weapons: The French 75mm cannon