Canon de 75 (Mle 1915) Saint-Chamond - Mondragon
by Charlie Clelland

St Chamond 1

The 75mm field gun built by Saint-Chamond before and during WW1 had an unusual design history. The design was originally specified by the Mexican Army General Manuel Mondragon in 1890s. However, Mexico did not have the industrial capability or capacity to build numbers of field guns so the Mexican Govt. employed Compagnie des Forges et Acéries de la Marine et d'Homécourt (Saint-Chamond) to do the detail design and produce the gun. The St-Chamond field gun detail design was completed by a team headed by Lt.Col. Emile Rimailho, the Technical Director of Saint-Chamond. Rimailho had been a member of the team that designed the 75mm Mle 1897 field gun and had designed the 155mm Mle 1904 howitzer when he was employed by the State Arsenals. The 75mm St-Chamond design seems to have been completed about 1905/6 and perhaps 100 guns, although this number is uncertain, were built for the Mexican Army and delivered before 1910.

Saint-Chamond apparently acquired rights to the gun design and attempted, unsuccessfully, to sell it to various countries before WW1. Belgium tested a battery of Saint-Chamond guns before deciding to purchase 75mm Krupp export guns.

The 75mm St-Chamond light field gun was a conventional design for the time. The breech was a single motion interrupted screw similar to the Schneider breech. The elevation gear was a simple concentric jack located between the carriage frames just forward of the breech. The traverse gear was similar to other French guns in that the centre of the axle was threaded and the carriage moved across the axle by a worm gear with the spade at the end of the trail as the pivot point. The recoil/recuperation mechanism was a hydraulic recoil absorber with a pneumatic recuperator similar to the 75mm Mle 1897. Cartridge ammunition was used with both Shrapnel and HE projectiles. The Saint-Chamond gun was about 100kg lighter than the 75mm Mle 1897 with a slightly shorter barrel which gave a shorter max. range than the Mle 1897. The gun was towed by 6 horses with a limber containing 36 rounds of ammunition.

Data 
Calibre75mm L/28.5
Muzzle Velocity513 m/sec
Weight of Gun (emplaced)1090kg
Weight of Gun (with limber)1770kg
Elevation-8° to +17°
Traverse
Max. Range8000m (theoretical)
6500m (practical)
Rate of Fire15 - 18 rounds/min
ProjectilesShrapnel 7.24kg
HE 5.5kg


St Chamond 9 St Chamond 14 St Chamond 15
St Chamond 16 St Chamond 17

Mexican Service

The 75mm St-Chamond guns were delivered to Mexico before the outbreak of the Mexican Revolution of 1910-1920. This conflict is quite confusing and seems to have been a series of regional civil wars overlaid by regime changes of the central government. The St-Chamond guns served with a number of the warring factions.

St Chamond 2 St Chamond 3 St Chamond 4 St Chamond 5

French Service

The French Army ordered 40 batteries of St-Chamond guns in September 1914 and then cancelled the order in November 1914 since they thought that they would have sufficient 75mm guns. In May 1915 200 St-Chamond guns were ordered in "compensation" for the earlier cancellation. The guns were delivered in 1916. It is not known whether they were issued to operational units. The "Mle 1915" seems to be an informal designation, it is not known if the St_Chamond guns were officially accepted. The French order St-Chamond guns used the same ammunition as the 75mm Mle 1897 - it is not known whether this is true for the Mexican guns. Most, if not all, of the French order St-Chamond guns were fitted to the Char Saint-Chamond tank.

Char Saint-Chamond

The Char Saint-Chamond was the second French tank to enter service. It was armed with a 75mm field gun, the heaviest tank gun in WW1. This armament was installed on the insistence of Gen. Estienne and had the unfortunate consequence of making the front overhang of the Saint-Chamond excessively long and limited the ability of the Char Saint-Chamond to cross trenches and negotiate bad ground. This problem was a consequence of the design of the traverse mechanism in French field guns1. The whole carriage was moved across the axle pivoted on the spade to achieve gun traverse. When the 75mm field guns were fitted into a tank the whole carriage had to be fitted as well.

There is a perception that Saint-Chamond somehow used their own 75mm gun without permission and the royalties for the gun went to Lt.Col. Rimailho. However, this is just a myth. The original schedule2 agreed between Saint-Chamond and the French Army for the armament of the Saint-Chamond tank was that the tanks up to No.150 should have the 75mm St-Chamond gun, Nos. 151 to 211 would have the 75mm Schneider Mle 1912. The Schneider gun was never fitted because Schneider could not supply the 75mm guns. Since the first 48 Saint-Chamond tanks were unarmed (char caissons) there were enough St-Chamond guns to make up part of the shortfall - the rest of the planned Schneider gun tanks were armed with the 75mm Mle 1897. General Mourret decreed that all Saint-Chamond tanks from No.212 to 399 (the rest of the order) would have the 75mm Mle 1897.

St Chamond 6 St Chamond 7

Israeli Service

The state of Israel was created by a vote in the UN in 1948. Immediately the surrounding Arab States declared war and attempted to invade and eliminate Israel. The new state of Israel acquired weapons wherever it could by whatever means. 32 Mexican St-Chamond guns were purchased by Israel from Mexico and saw service during the War of Independence. Unlike the 75mm Krupp guns Israel acquired from Switzerland the St-Chamond guns retained their wooden wheels throughout their service. In Israeli service they were nicknamed "Cucarachas" (Cockroaches). There are 3 surviving Saint-Chamond guns in Israeli museums.

St Chamond 8

Surviving St-Chamond guns

2 Saint-Chamond guns at Batei HaOsef (Israel Defense Forces History Museum), Tel Aviv

St Chamond 10 St Chamond 11 St Chamond 12

Beyt ha-Gdudim museum in moshav Avihayil

St Chamond 13

Images - User "Bukvoed" - Wikimedia Commons

Notes

Sources