Looking to fulfill a long-range heavy artillery requirement during World War 1 (1914-1918), the French undertook development of a new 155mm field gun. This became the "Canon de 155 Grande Puissance Filloux mle 1917", otherwise known as the Canon de 155mm GPF (Model of 1917). The weapon was designed by French Colonel L.J.F. Filloux and pressed into service as soon as it was made ready to stabilize the shortage of such weapons in the French inventory.
World War 1 kicked off a series of alliances which led to varying parties committing to a war they either wanted or did not. For the French, they primarily faced off against long-time enemy Germany who sat at her doorstep. The German Empire made up one-third of the Central Powers, joined by the Austro-Hungarian Empire and the Ottoman Empire. France was assisted by the Russian Empire, Britain, Belgium and others in time.
As built, the GPF was a large, massive artillery piece requiring use of a wheeled carriage. Travel weight alone was 28,500lb and the L/38.2 barrel measured in at 20 feet long. Multiple crew, as few as eight, were required for the weapon to perform at maximum efficiency. For artillery pieces, this meant in accuracy and rate-of-fire. Each 155mm shell was loaded separately from its cased charge load. The gun mounting system allowed the barrel an elevation span of 0- to +35 degrees for both direct and indirect line of fire. Traversal was limited to 60-degrees to either side. An integral recoil mechanism was crucial to dampening some of the violent recoil forces involved though no muzzle brake was fitted. Each projectile exited the barrel at approximately 2,400 feet per seconds out to a maximum range of 21,325 yards. This reach, coupled with a 155mm high explosive shell, ensured that the enemy would be kept on guard some distance away. The entire gun unit sat atop a split trail carriage which could be towed by animal or vehicle. The two trail arms were spread apart when the gun was made ready and this aided recoil somewhat. The wheels were solid metal spoked types.
During World War 1, the gun was eventually taken on by the American Army (and Marines) as a standard long-range artillery piece. Local production began in 1917, the same year the United States officially joined the war. These guns were first designated M1917 and then M1918 and managed a long service life until replaced by the M1A1 "Long Tom" of equal caliber. Long Toms emerged from design and testing in the 1930s which meant that M1917/M1918 guns existed into the 1940s for the Americans.
Availability after World War 1 meant that the GPF was still in circulation in the lead-up to World War 2 (1939-1945). Along with American usage, the French retained their stocks as well, those these were pulled out of reserve storage to, once again, shore up a limited artillery inventory. The French were now fighting for their freedom against the might of the German Army under the supreme direction of Adolph Hitler.
Despite a valiant defense, the French perimeter collapsed and Paris was given up to the enemy. Several hundred GPF guns then fell to the conquering Germans how were all too eager to reconstitute the weapons into their own growing stocks (a common practice for the Germans during the war). In German nomenclature, the French artillery piece existed as the 15.5cm K 418(f) - the lower-case "f" to signify their French origins. These guns then served in heavy artillery units with the Germans while others were set up as static defenses in coastal regions.
Other operators of the French gun became Australia, Chile and the Philippines. After the end of World War 2, the series was replaced in the French inventory.