By the beginning of the First World War, the German army was armed with a large number of various large-caliber guns. In addition, there was a certain amount of special artillery power. The available artillery was distinguished by sufficient firepower, however, the effectiveness of solving combat missions was negatively affected by the not too high mobility of such systems. Several options were proposed to solve this problem, including the installation of existing tools on railway transporters. The first version of such a gun was the 15 cm SK Nathan system.
Soon after the start of the war, an original method was proposed to increase the firepower of artillery formations, which did not require additional costs. As a means of strengthening ground artillery, it was proposed to use specially modified naval guns. Mounting a ship or coastal gun on a wheeled carriage made it possible to transfer to a specified position with the further destruction of specified targets. However, the implementation of such a proposal was associated with certain difficulties of a technical nature.
The fact is that the requirements for naval guns differed markedly from the requirements for land ones. The artillery of a ship or coastal battery had to be distinguished by a long firing range and the ability to penetrate armor. At the same time, there were no significant restrictions on the dimensions and weight of the structure. In connection with such features, the adaptation of naval guns to a new role turned out to be quite difficult. To effectively use the existing system, it was necessary to develop new means of transportation, as well as find suitable tractors.
Complex 15 cm SK Nathan at the firing position. Conveyor structure and coulters fixed to the ground are visible
In 1915-16, a new idea was proposed and worked out concerning land platforms for naval artillery. It was proposed to recall the previously used special transporters based on a railway platform. The locomotive of the existing model was supposed to become the tractor, respectively. This technique first appeared in the middle of the 19th century and showed itself well. The railway guns had high firepower with a fairly high mobility. The gun could be delivered to the desired area as soon as possible. The only limitation in terms of mobility was the need for the presence of railways.
The first serial railway gun for the German army was developed by the Krupp concern. In accordance with the weapons designation system that existed at that time, the complex was named 15 cm Schnelladekanone L / 45 in Mittelpivot-Lafette (“15 cm quick-reloading cannon with a 45 caliber barrel on a rotating installation”), or 15 cm SK for short. The project was also named Nathan. According to some reports, some serial guns subsequently received their own names, in which one or another "surname" was added to Nathan's name.
As a basis for a promising gun mount, it was proposed to use a railway platform of the original design. In its composition, both existing components and assemblies were to be used, as well as completely new products. In particular, it was necessary to develop a frame from scratch that fully meets the new requirements. The proposed platform could be connected to any existing locomotives and trains, which gave appropriate results in terms of mobility.
The main element of the platform was a frame structure with fasteners for all other components. Due to the large mass of the gun, the need to reduce the size and reduce the recoil shoulder, the central part of the platform was lowered relative to the front and rear. The lower units of the platform center were located at the lowest possible height above the rails. On the front and rear of the platform, two biaxial bogies of a standard design were installed, equipped with wheelsets with European gauge. The wheelsets had an elastic suspension. The carts could rotate relative to the platform, providing cornering.
A characteristic feature of naval guns was increased firepower and a corresponding recoil momentum. It was proposed to solve this problem by securing the entire gun mount in place. The platform of the 15 cm SK Nathan complex did not receive jacks for hanging over the tracks. The transfer of recoil to the ground was to be carried out using several opener anchors on chains. Chains were attached to the sides of the central part of the platform. The coulters had to be driven into the ground by tightening the chains. Such means of stabilization did not differ in high performance, but they were quite simple to manufacture and effective in terms of application.
In the center of the platform, the authors of the project placed a pivot for mounting a swivel gun mount. It was proposed to install the gun on a pedestal and complete it with some additional units. To protect the crew and the breech of the gun, a large armored wheelhouse was attached to the rotary part of the installation, having a rectangular floor of great length, as well as relatively high frontal and side plates. The stern sheet was missing, but for the greater safety of the gunners, the wheelhouse was equipped with rear handrails. When performing horizontal laying, the wheelhouse rotated with the gun.
All these technical tricks were necessary for the correct and convenient use of the existing 15 cm SK L / 45 naval gun. This gun was developed in the middle of the first decade of the 20th century and was intended to arm promising ships of various types, as well as for use as part of coastal batteries. For use with the gun, seven variants of the pedestal installation with various design features and capabilities were offered. Four variants of the installation had a fully enclosed tower, three more - shield cover. Systems with a similar architecture differed from each other in guidance systems and, as a consequence, in the permissible elevation angles, which accordingly affected the maximum firing range
15-cm cannon on a coastal pedestal mount
The 15 cm SK L / 45 cannon had a 149.1 mm barrel, 6.71 m long (45 calibers). The rifling pitch varied from 1120 mm at the breech to 605 mm at the muzzle. A wedge gate sliding in the horizontal plane was used. The gun used separate loading and could use different types of ammunition. The maximum muzzle velocity of the shells reached 840-850 m / s. The firing range, depending on the elevation angle and the type of projectile, exceeded 22.5 km.
In the pre-war period and after the outbreak of the First World War, several types of 149-mm shells for various purposes were created. Marine and railway guns could use armor-piercing shells weighing 40 or 51 kg, 40 or 44, 9-kg high-explosive, as well as fragmentation shells with similar parameters. The shells carried an explosive charge weighing up to 3, 9 kg. For throwing ammunition, casings with a variable charge were used, the maximum mass of which was 9, 9 kg. Regardless of the type of projectile, the rate of fire reached 4-5 rounds per minute.
The design of the gun mount, mounted on a railway platform, made it possible to carry out circular aiming of the gun. Nevertheless, due to the high recoil power and some other factors, it was possible to shoot only when the gun was turned perpendicular to the paths or with a small deviation from this direction. In this case, the optimal distribution of the mass of the implement and the recoil momentum on the installation structure, rails, soil and openers was ensured. The elevation angles varied from 0 ° to + 45 °.
In terms of its dimensions, the 15 cm SK Nathan railway gun corresponded to standard flatcars. The mass of the complex, excluding ammunition, reached 55.5 tons. Such dimensions and weight made it possible to operate the system on any existing railways and transport it with all available locomotives, both separately and in trains. The minimum serviceable train consisted of a steam locomotive, a gun transporter, and a separate wagon for transporting ammunition and crew.
The 15 cm SK L / 45 guns were produced in series for several years and were used to arm several types of warships. The presence of mass production, as well as the refusal to build some ships, made it possible to quickly establish the production of new military equipment. The first samples of the Nathan railway system were built already in 1916, and soon found themselves in the army's artillery units. They were supposed to be used as a mobile means of reinforcing field artillery.
The ground forces from the very beginning showed an interest in the original development, which accordingly affected its future. The production of the 15 cm SK Nathan railway installations continued until 1918 and ended shortly before the end of the war. During this time, the Krupp concern has manufactured at least 21 installations. A more accurate calculation is not possible for a number of reasons. Serial installations of the new type, in general, corresponded to the original project, however, as they were released, the design of the equipment was being finalized. Railway guns could differ from each other in the design of the pillar installation, wheelhouse, guidance systems, etc. The overall look, however, remained unchanged and matched the original design.
Details of the operation of two dozen 15 cm SK Nathan railway installations are unknown. It can be assumed that such weapons were used in various operations, where they worked together with field artillery on different carriages. The relatively high firing range made it possible to strike at various enemy targets using the existing railway network, and also without being exposed to a serious risk of retaliation. A good rate of fire, in turn, made it possible to send a large number of shells to enemy positions in the shortest possible time. After the completion of the firing, the gunners could quickly leave the position.
15 cm Feldkanone IR gun on wheeled carriage
However, the Nathan system was not without its drawbacks. Perhaps the main thing was the specific characteristics of the shells. The 15 cm SK L / 45 cannon was originally created as a weapon for ships and coastal batteries, which affected the design of its ammunition. The available 149, 1-mm shells had thick walls and carried an explosive charge of no more than 3, 9 kg. Such a projectile could be used against armored ships and some ground fortifications, but for solving other problems, the power of the charge could be insufficient. For example, in terms of fragmentation and high-explosive effects, the projectile of the Nathan cannon could be inferior to the ammunition of other systems.
There is reason to believe that when used at the front, railway guns were able to show acceptable results, but the small number of such systems in comparison with other artillery models did not allow leaving a noticeable mark in the history of a particular battle. Field guns of smaller caliber and different power were available in the troops in much larger quantities, which affected the ratio of results. Nevertheless, due to their large caliber, railway systems proved to be a convenient means of reinforcing existing field artillery.
It should be noted that one of the "competitors" of the system on the railway platform could be another modification of the naval weapon. Based on the existing sample, the 149, 1 mm 15 cm Feldkanone IR cannon was created, using a towed wheeled carriage. In terms of its characteristics, such a weapon was similar to the "Nathan" system, but it had some differences, primarily related to the peculiarities of transportation.
Railway guns 15 cm SK Nathan, which became the first representatives of their class in the German army, confirmed the viability of the original idea and showed the fundamental possibility of continuing work in this direction. The military ordered the development of new similar systems with other artillery units. Among other things, it was again proposed to adapt naval guns for use on land. With the help of projects that followed "Nathan", over time, Germany was able to create a fairly large and developed grouping of railway artillery of large and special power.
All available guns, built before the end of the war, were actively used in various operations. The careers of these samples, including the 15 cm SK Nathan, ended after the end of the fighting. Subsequently, the Versailles Peace Treaty was signed, according to which the German army was deprived of the right to have in service and to use artillery systems of some classes. All the available railway equipment fell under such a reduction. By the early twenties, all 15 cm SK Nathan complexes were disposed of or transferred to third countries. The saved tools were operated by new owners for some time, but by the end of the twenties they were disposed of in connection with the development of a resource.
