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75 mm field gun [7-veld]

Introduction

During the last two decades of the 19th century rapid technological developments in the weapon and metallurgic industry forced armies all around the world to invest a great deal of funds in replacement of their artillery. The design revolution also produced the standard field-artillery gun of the Dutch army that was in use in May 1940.

Prelude

It all started with the new technology of breech-loaded in stead of front-loaded guns. This development was a consequence of the invention of both the percussion trigger device and the improved production-quality of guns, that facilitated strong breech- and seal constructions. This development went simultaneously with the rapid development in metallurgic processes. The industry went through a quick process of better controlled steel-production and milling, which improved the metal-quality to such extend that far better yields could be achieved with basic and enriched steels and basic alloys. As such designs were possible to develop breech-loaded guns from bronze- and steel/alloy materials.

Another development that contributed to the rapid modernisation of artillery pieces was the revolution in chemistry, more in particular the development of new stabilized powders. During the 1880's and 1890's many new chemical compositions were developed that contributed to much more powerful and stable explosive compounds. This resulted not only in a dramatic decrease of steam-production at detonation [important in respect to stealth and vision] but it also facilitated the gun-designers with better controllable and far more powerful powder-loads and cartridges. The development of unity-ammunitions [projectile and charge in one shell] caused yet another step forward in gun [and rifle] development.

Early 20th century further metallurgic progress resulted in even better alloys. Especially the nickel-based alloys facilitated a leap forward in barrel strength. In stead of half a metre weight breech-pipes - that were constructed by complicated layer-fabricated methods - gun barrels became slim and lighter. Just before and during WWI stainless steel was discovered by accident and soon even more improved alloys appeared on the market. In combination with a much improved milling process [as a result of the Bessemer Peer process] steel could be produced with a much more controlled carbon and nitrogen content. This improved the metal-fatigue component and made guns not only longer lasting products but also capable of sustained the severe conditions that went along with rapid fire operation. Last but not least the rapidly improving quality of guns and ammunitions resulted into an increased range of artillery pieces in general.

This entire revolution in gun technology was unprecedented in history. From the first gun in the 11th century up to half way the 19th century guns had developed very gradually. When new chemical and metallurgical discoveries boosted in the second half of the 19th century a true revolution in gun development was witnessed that would last until the interbellum, after which the pace of new developments would fall back again.

One of the most professional plants for gun fabrication in the 19th and 20th century was the German manufacturer Krupp. This company was one of the first that could produce guns of high quality with a very reliable operation.

During the last decades of the 19th century the Dutch army purchased arsenals full of new artillery pieces. Shortly after the end of the French-Prussian war in 1870-1871 the Dutch purchased a whole arsenal of bronze breech-loaded guns. These new bronze guns were obsolete at the very moment of delivery. That's why their arrival was soon followed by orders for a great variety of newer guns, like the Krupp fortress-guns of 12,5 cm and 15 cm [1878] and the Krupp field-guns of 5,7 cm and 8,4 cm. All these guns were still in service in May 1940. Also plenty of new navy-guns and coastal-fortress guns were procured from Krupp.

The introduction of the 7-veld

When the design revolution started to stabilize, the Dutch army filed requests for the procurement of a new standard field-artillery gun that was relatively powerful, capable of producing rapid-fire but still mobile enough to form the backbone of the field artillery. First the military had considered the new 8,4 cm gun capable enough if a number of marginal modifications would be executed. Soon however, reasonable doubt grew whether this gun would indeed be able to match the standard of modern warfare and as such new inquiries were made for modern guns.

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7-Veld light field artillery

The selection of the new standard gun was given shape in the period 1895-1903. As said, the attention was primarily focussed on the modification of the existing 8,4 cm gun. In 1900 the first initiatives towards an entirely new product were noted. The choice fell on the new Krupp field gun [Krupp 7,5 cm Kanone M.02/03]. It was a rifled breech-loaded rapid-fire field-gun, constructed of nickel-steel. The gun was also fitted with a sectional cradle that provided for a hydraulic recoil-brake device. With its weight of just under 1,000 kg it was very easy to manoeuvre and mobile enough to fill the ranks of the quite extended Corps Horse Artillery. This Corps was dedicated to the task of direct support of the field-army troops and needed therefore ability to manoeuvre in close cooperation with the infantry.

The first 7-veld gun was introduced in 1904, and the first operational field-artillery units received the new guns in 1905. The total order at Krupp comprised 204 guns and 408 caissons. The Dutch Artillerie Inrichtingen [AI] later delivered another 100 guns to the army.

One complete gun-assembly comprised one gun, twelve horses, a drivers cart and two caissons.

At first the main ammunition ration for the new gun mainly comprised canisters and HE shells. As off 1912 the HE canister became prime ammunition too. This type of fused ammo could deliver a canister-charge overhead of attacking or manoeuvring enemy infantry.

The guns were organised in batteries. In the period 1905-1912 batteries comprised six guns each. Later, with the change of the Dutch militia law in 1912, batteries were formed from three guns each, which would be expanded to again six guns after mobilisation of the reserves. In the twenties the batteries were again reformed, this time to four guns per battery. Three batteries formed a battalion; three battalions a regiment. That organisation would stand until the 1940 war.

The 7-veld gun edition 1904 had a maximum range of 6,500 meter. Study of the WWI combat conditions and facts learnt that this range was too short to perform the task of modern infantry artillery-support. The military requested the local design agency HIH [subsidiary of the German Rheinmetall company - Germany was no longer allowed to have indigenous defence industry since the Versailles Treaty had come into force] to make a modification proposal for the existing gun.

From modification to mobilisation

In 1926 the modification of all 7-veld guns was initiated. The gun cradle was modified as well as the under-carriage design. The cradle and under-carriage modification made a much bigger barrel-elevation possible. As a consequence of opening up the plate between the two under-carriage legs, the barrel could now be tilted such that the recoil movement could end between the two legs. As such a considerable steeper elevation than before was created which improved the range dramatically to 10,000 meter. This increase in range was also possible due to the introduction of a modern HE shell which had improved ballistic features.

The 7-veld was capable of rapid-fire for at least 5 minutes continuously. A well trained gun-crew was capable of firing 40 rounds in that period. As such a battery could produce a barrage of 160 rounds in 5 minutes. Given the [Dutch] standard perimeter-width [for one battery 7-veld] of 300 meter, this production of 160 rounds in a 5 minute time-lapse offered an enemy quite a challenge to overcome. At the same time one should realise that a single gun ammo-ration was 40 grenades. The standard caisson load for one piece was no more than 80 rounds total [one ration of 40 rounds per caisson]. Re-supply came from the ammunition train.

The 7-veld guns were all operated with horse traction. Six horses pulled the gun with driver-cart, six horses for the two caissons and one horse for the gun commander. There was one 7-veld unit that was motorised, and this exception was due to the fact that it was part of the Light Brigade [later the Light Division]; a fully motorised Field Army unit that was organised as a quick reaction force. This unit was equipped with Fordson tractors and DAF Trucks.

The modified 7-veld gun was operated by a crew of six men and a gun-commander [NCO]. The crew comprised a gunner-aimer, a loader and auxiliary-aimer, a breech-operator / trigger-operator, a fuse-operator and two ammunition aids. Four crew members were directly involved in the operation of the gun, whereas three men were specifically ammunition occupied.

A standard 7-veld battalion with twelve guns comprised about 600 men and was usually commanded by a Captain or Major. The battalion staff and supporting unit comprised 120 men. The batteries each had 4 guns, 2 light machineguns and 140 men. Each battalion had an ammunition train attached. A battery was usually commanded by a Captain or 1st Lieutenant. The battery usually had four or five officers, about ten to twelve NCO's and about 120 corporals and regulars.

7-veld in Artillery Regiments

The 7-veld gun was the standard artillery piece in almost all field-artillery regiments. The Dutch army had 27 artillery regiments. The first eight of these regiments were organised in a simular fashion. Each of these regiments comprised three artillery battalions. The first and second battalion comprised three batteries of four guns of the 7-veld guns each. The third battalion had either twelve howitzers of 12 cm or twelve of 15 cm. As such the first eight artillery regiments had each twenty-four guns of 7,5 cm plus twelve howitzers of either 12 or 15 cm.

The higher artillery regiments were all but homogenous in their organisation. We shall not elaborate further on those regiments in great detail. Many of these higher regiments also had one or two battalions with 7-veld guns.

At the eve of battle there were 304 guns of 7-veld ready for action and assigned to field units. Of this total 284 guns were assigned to regular field-artillery batteries, and 16 were assigned to the Light Division artillery battalion [21 Artillery Regiment]. Four guns were being overhauled at the AI factory. Probably the total number of 7-veld guns available to the army accumulated to about 320 guns. The exact number is unknown.

The 7-veld guns were not particularly modern in 1940, but could certainly survive the comparison with the standard guns of the other allies. The 7-veld was a reliable gun that was capable of producing accurate fire. The explosive power of the 7,5 cm HE shells was acceptable although room for improvement was certainly noted.

In May 1940 no more than 2,000 rounds [per gun] were held in stock. The AI was capable of production of 7-veld shells in quite large numbers, but by far not enough to hold pase with war consumption. The small ration for each gun did however not miss its impact on artillery commanders, who were instructed to limit length and intensity of fire missions and to be selective in concurring fire mission requests. Unfortunately the psychological side-effect of this instruction was that artillery commanders proved extremely rigid in admitting opportunities or supporting fire-missions. Just a few batteries were able to outperform themselves due to very capable and bold commanders. Nevertheless German field-commanders showered the Dutch artillery with compliments of awe and respect after the capitulation; and these compliments were heard at so many occasions that one might conclude that they were more than just plain courtesy of the conqueror.

The Germans confiscated many 7-veld guns intact. The German army adopted many of these guns and registered these under the type-identification 7.5 cm FK 243.

Specifications

Manufacturer:  Krupp, Essen (Germany)
Calibre:  75 mm [30 calibre barrel-length]
Material:  Nickel-steel
Length barrel:  2,192 m.
Fire rate max.:  6 - 8 rounds / minute (max. 5 min.)
Muzzle velocity:  520 m/sec.
Ammo types:  - Canister
- HE
- HE Canister
- Solid HE [armoured target]
Weight:  Barrel: 350 kg.
  Gun (pre-modification): 990 kg.
  Gun (modified): 1250 kg.
Max. range:  Pre-modification: 6.500 m.
Max. range:  Modified: 10.000 m.
Introduction:  1904/1905
Number available in May 1940:  304 284 in field artillery batteries
    16 in motorised battery
Remarks:  - a caisson weighted 1100 kg. including 40 rounds
- two caissons per gun
- six horses were required for gun-traction
- crew: 6 men plus commander