The de Bange 155 mm long cannon mle. 1877 (or more briefly the 155 L de Bange) was the French artillery piece that debuted the 155 mm caliber in widespread use today. Although obsolete by the beginning of World War I, the 155 L was nonetheless pressed into service and became the main counter-battery piece of the French army in the first two years of the war.
Development and 19th century deployment
Drawing from the experiences of the Franco-Prussian War of 1870–1871, a French artillery committee met on 2 February 1874 to discuss new models for the French fortress and siege artillery. Among them was a piece in the 14 to 16 cm caliber range. After several meetings, on 16 April 1874 the committee settled on the 15.5 cm caliber. In the subsequent program-letter of the committee, dating from 21 April, the caliber was for the first time expressed as 155 millimeters. (The other two calibers decided by this committee were the 120 mm fortress and siege cannon and the 220 mm mortar.) Three different 155 mm prototypes were tested in Calais in 1876. The winner was Charles de Bange's model, and the French government ordered the first 300 pieces in November 1877.
In common with the other de Bange cannons, the 155 L had a hooped steel construction with gain-twist rifling. In its original (1877) conception, the cannon required a wooden platform from which to fire. Its recoil was absorbed simply by friction with the platform, and the 155 L had to be pushed back into position after every shot. In 1883, the Saint-Chamond hydraulic brake was introduced to better absorb recoil. This brake was a separate piece of equipment that anchored the cannon's carriage to the firing platform and returned it into position after about 110 cm of recoil.
Approximately 1,400 pieces of 155 L were built in the 19th century. Most were placed in France's numerous fortresses of the time (part of the Séré de Rivières system), most notably at Toul, Belfort, and Verdun. In 1882, about 200 pieces of 155 L were retained for offensive operations as siege artillery. In this role, each 155 L gun was drawn by ten horses.
French service in World War I
At the turn of the century the de Bange cannons were rendered obsolete by the newer quick-firing guns using the French 75 recoil system, in which only the tube recoiled. Besides the technical obsolesce issue, the French army's doctrine at the time emphasizing mobility—"75 for everything" had become its universal mantra for field artillery. The 155 mm de Bange was therefore retained in forts and in reserve. On 2 August 1914, the French army had 1,392 pieces of 155 L de Bange, either in depots or in fixed positions; not a single one was part of the equipment of a mobile unit. On the eve of World War I, a typical French army corps was equipped with 120 75-mm cannons, while its German counterpart had 108 77-mm, 36 105-mm, and 16 150-mm pieces.
The first engagement of the 155 L was probably by the 8th Foot Artillery Regiment firing from place fortifiée d'Épinal during the Battle of the Mortagne on August 27. The first artillery duels of the war quickly convinced the French of their inferiority in heavy artillery relative to the Germans. Thus it was seen necessary to enhance the mobility of their 155 mm guns. In October 1914, a program was started to fit the 155 L wheels with a system of metallic soles and gutters articulated together. The use of this system—known as cingoli or Bonagente wheel belts after the name of their Italian inventor—eliminated the laborious construction of wooden platforms. The cingoli tracks added 800 kilograms to the gun's total weight, but saved 5 tons of bedding material that otherwise had to be transported for the wooden platforms. The use of cingolis also reduced the time required to deploy the 155 mm gun from 5–6 hours to just one hour.
In an attempt to match the field artillery employed by the Germans, on 27 November 1914, each French army corps was endowed with a heavy artillery group. By November 30 of that year, 112 pieces of 155 L had already been mobilized for this purpose, although other types of heavy pieces were allotted for these groups as well. In October–November 1915, a more structured organization was introduced, grouping the 155 L in mobile service in 30 heavy artillery regiments. Twenty of these regiments were horse drawn (totaling 320 pieces of 155 L), while ten regiments used motorized tractors for transportation and had a mixture of 155 L and 120 L de Bange guns. By 1 August 1916, the number of 155 L guns in mobile service (regardless of means of transportation) reached 738 pieces. The number of motorized 155 L guns also increased from 40 at the end of 1915 to 128 in July 1917.