Canon de 120mm mle 1878

[David]

At the outset of the Great War, the French Army had put an enormous amount of faith in their famous "75", that they said could do anything and everything. And it was indeed a formidable weapon, but it soon became apparent that even this Gun could not perform all the tasks needed, especially when the war turned static and fixated around entrenchments rather than maneuver. Heavier guns were needed. Also, the rate of loss exceeded all calculations. (In the first 16 months 2.750 guns were lost, out of a total of 4.800!) This forced the French Army to use older or even obsolete guns, in a desperate effort to fill the gap, and to provide the troops with much needed heavy Fire Support. That is the reason why the 120mm Cannon Model 1878 was pressed into service, despite it's obvious age, shown primarily by it's rigid mount on a "Napoleon-style" carriage. The lack of a modern system of Recoil meant, among other things, that the gun had to be relaid after each shot, greatly reducing the rate of fire. (This was, however, not something uniquely French: all nations used older guns with rigid mounts in the war, but the French were more hard-pressed than most, on account of their mentioned over-dependence on the "75"..) It must be said, however, that a gun is much more than it's recoil system, and although the carriage was definitively old-fashioned, the gun barrel itself of the 120 Long was - like it's old counterparts the 90mm Model 1888 and the 155mm L Model 1877 - quite functional. So the gun could hurl a special shell of 18 kilos a maximum of 12.4 kilometers, which was quite acceptable. The normal range was some 8-10 kilometers. The cannon could use eight different types of shells, including shrapnel, HE, gas and incendiary. The charges were bagged - which was an advantage, as it saved on the brass or copper used to shell cartridges. Some guns were fitted with simple shields. The Breech was of the De Bange screw type, and the gun was fired using a Friction Device. Note that this of course was not a Field artiller piece. The 120 L was initially organized in batteries that were used as Heavy Artillery Assets at the Army level. (In the early days of the war each army had between 3-5 groupes with 120mm L, its counterpart the 120mm C and the advanced but overly complex 155mm Rimailho, each groupe consisting three batteries with 4 guns each, i.e. 12 guns.) The gun was either pulled by horses - it required six of them, with the ammunition caisson transported by another six - or by a truck - in which case the caisson was pulled together with the gun. (Notice the time taken from one shot to another. The finns used the gun during WW2, and they said jokingly that in action it required to Artillery Controllers: one to see where the grenade landed, one to see where the gun went.) As mentioned, one of the problems with a rigid mount, was that the gun kicked quite a lot on recoil, especially if using gigger charges, which meant that it required relaying between each shot. Some means were, however, used to minimize this obvious disadvantage. One was that the gun was deployed on special wooden platforms, where a sort of hydraulical recoil device was attached underneath the carriage. (See this plan.) The recoil device pulled the gun automatically back to it's previous position - or somewhere quite close to it. (This was of course combined with another standard WW1-device: the simple sloping Gun Chocks, which helped the gun to roll back after firing.) The problem with this system was that it was quite heavy to transport, and time consuming to set up. (The platform required some 5-6 hours to complete.) Another option was to combine the Gun Chocks with "Wooden Feet", or as they were called in the French Army "Ceinture de Roues", which in fact was a sort of primitive Caterpillar Feet. (Each wheel required some 10-12 "flats", connected by an equal amount of segments.) The Ceinture hindered the gun from straying sideways in it's recoil, and when rolled back - again with the help of Gun Chocks - it returned pretty much to the same position as it had when it was fired. Note that this was actually the main advantage with the "Wooden Feet": they did increase the guns mobility on bad roads and over difficult terrain, but this was secondary. The really big advantage for the 120 L, was that the required equipment was far lighter than the above mentioned Recoil Device, and that the setting up time was less than an hour - as compared to the 5-6 it took to set up a platform. The 120L was eventually phased out of the French organization, and few if any remained in service at the end of the War. Technical Data Calibre 120mm Weight of Gun 3,74 tons Maximum Range 12.4 kilometers Muzzle Velocity 265-613 metres per second Weight of Shell 18-20 kilograms

120mm Cannon Model 1878 Walkaround

The gun below is yet another one of those beautifully kept WW1 guns at the excellent Army Museum in Brussels. (Don't miss this museum if you are near-by!)