As early as the 1880’s the German General Staff saw a need for a field mobile heavy howitzer. This may seem an obvious conclusion today but this early development had few counterparts. The concepts of land warfare were well established concerning artillery employment. Light field artillery was part of a division’s organization. It provided swift moving, direct fire support to the infantry and cavalry. If battlefield maneuver ended and one side was bottled-up in a fortress or city, then siege operations began. This was the niche for heavy artillery of the army corps. It was used by the force conducting defensive operations as fortress artillery and by the force conducting an offensive as a means to attrit and break through. No nation typically used heavy howitzers as a normal part of a maneuver organization or incorporating it into their field tactics. The siege of Plewna in the Russo-Turkish War (1877-78) was an incident in which Turkish Infantry was able to take cover behind the breastworks where they were immune to the flat trajectory of the Russian Field Artillery. It was generally believed that if the Russian Infantry assault had been supported by continuing fires form heavy mortars they would have met with greater success.1 This gave a tangible example to Russian and German heavy howitzer advocates. As a result of this catalyst, in Russia a heavy field mobile howitzer design evolved, designated 6-inch Field Mortar Model 1886. First steps toward a new design in Germany took existing 12cm’s and 15cm’s, which were fitted on high carriages, and required firing foundations. These types were not suitable for anything more than siege artillery operations and were viewed with great disdain by maneuver commanders. Despite this, they could serve to test projectiles and help determine minimum requirements for this new generation of heavy artillery for the field. On 6 December 1888 the “General-Artillerie-Komitee” was nominated by the “Allerhoechste Kabinettsordre” to review results of tests conducted with these weapons. In addition the General-Artillerie-Komitee was ask to decide weather a new short 12cm gun should be introduced to fulfill this new requirement for the Field or Foot Artillery. In October 1888 the General-Artillerie-Komitee and the “Artillerie-Schiessschule” conducted firing tests and found 12cm’s insufficient when used against entrenched infantry targets.2 It was at first thought that new projectiles with high explosive would sufficiently improve this performance and might even make heavy indirect fire artillery unneeded because of the greater effects expected from lighter field guns using HE ammunition. However, because no date could be fixed for the introduction of HE ammunition, tests resumed with the short 12cm gun.3 These new tests emphasized the importance of effects on infantry dug in with cover. Also, because of the inability of the 12cm gun to meet these requirements, test were continued with 13.5cm, 15cm and 17cm howitzers. Tests proved that only a 40-kg projectile with an explosive charge of 10 to 12 kg was able to penetrate thicker improvised covered trenches.4 Such a large explosive charge could not be placed into a 13.5cm projectile, since too great a projectile length would have affected accuracy.5 It was found that the 15cm best corresponded with the requirements and on 8 May 1891 was the howitzer caliber selected by the APK. In that same year Krupp was awarded a contract by the APK to design a 15cm howitzer suitable for field operations, with a minimum range of 5000 meters and a travelling weight no greater than 2,800 kg. The resulting product was a howitzer made of nickel steel designed by Direkor Gross of the Krupp Engineering Department. This “new” steel was stronger and lighter, making barrel weight low enough to be practical for field use. Carriages were supplied for testing by Krupp and Spandau. Advances in metallurgy by Krupp were fundamental to the practicality of field mobile heavy artillery. Previous heavy pieces had simply been too cumbersome to support typical maneuver needs. Ultimately the Spandau carriage was selected because of its lesser weight along with the Krupp howitzer barrel.6 In field trials, what would become known as the s.F.H. 15cm proved successful. It was shown that the s.F.H. could be transported by a driver-team of six heavy horses. Firing platforms were found to be unnecessary, however, cane mats were often used to keep the wheels from bogging into the earth recoil-after-recoil. For prolonged stays in a firing position, wooden recoil wedges were brought up and placed to the rear of the howitzer. These wedges both took up the recoil and made the task of manhandling the howitzer back into position easier.
Differing from Field Artillery, which used the mil scale (0-6400), this weapon was fitted with a non-optical indirect fire sight graduated from 0-5800 and was years latter fitted with an optical “dial” sight graduated from 0-5760 (one sixteenth of a degree). These sights allowed the s.F.H. 15cm to be “laid” or made parallel by a single “aiming circle” or "director". The latter aiming circle was capable of magnetic laying with a removable compass also graduated from 0-5760. Forward observers, many kilometers down range, could spot targets and convey a call for fire, using, believe it or not “loudspeakers”. Fortunately, soon this was updated with field phones. A fire direction control officer worked the call for fire as a geometry problem for “deflection” or azimuth and a physics problem for “quadrant” or elevation. In the fall of 1900, after watching a live fire exercise of the Foot Artillery Guards Regiment near Munster, His Majesty William II, in his analysis particularly stressed the rapid emplacement by the Foot Artillery and its effectiveness. In order to acknowledge good performance and a changed perception of it s use, the 15cm howitzer was named “schwere Feldhaubitze” (s.F.H. or Heavy Field Howitzer) by the AKO on 6 September 1900.7
Below: Pre-war photograph of two 15cm. s.F.H. 1893 pieces and crew.
The s.F.H. is an important milestone in troop development and its organization as the heavy field artillery. Gone were the days of heavy siege guns being implaced with rented horses and hired drivers, and prolonged constructions before the opening of fire. This concept of quick moving infantry and cavalry forces directly supported by heavy field mobile artillery did not meet with popular acceptance among maneuver commanders, who saw heavy guns as a burden that would slow the speed of advance. This radical change had to be forced by dedicated officers who gained support for this new technically advanced arm of service from the highest levels of government. On 15 August 1900 William II addressed troops of the Tenth Army Corps on the Munster drill field, stating , “ We must apply all means that make possible for us a successful offensive. To that end the heavy artillery of the field army will and the (maneuver commander) will make himself guilty of a neglect of duty (who does not use heavy artillery).” 8 The s.F.H. in this respect served to introduce the concept of modern heavy artillery in support of maneuver forces which can be seen even today in practice with the M109A6 Paladin and in concept with the Crusader SP gun.
Below: Wartime period photograph of a 15cm. s.F.H. 1893 with recoil wedges and crew.
Despite the argument that this breech loading, indirect fire s.F.H. 15cm was among the first modern heavy field artillery pieces; two major improvements remained unfulfilled. The s.F.H. has no recoil mechanism. It is a friction primer fired weapon. Its rate of fire is low because it is necessary to relay after each firing. The next production howitzer to replace the s.F.H. would to the average on looker appear much like a World War II weapon. The s.F.H. 1902 has a reliable hydro-spring recoil mechanism. Its design incorporates the use of a percussion firing mechanism. It has a longer, more manageable carriage. As one might expect the development between the s.F.H. of 1893, and the s.F.H. 1902 was not direct. There was a V.H. 99 howitzer, which never went into general production, that smoothed the way experimentally dealing with the problems of recoil and the percussion firing mechanism.
During the late 1890’s both France and Germany introduced artillery with effective recoil systems such as, the French Schnieder 75mm Mle 1897, the Rimailho 155mm howitzer and the German Krupp l.F.K. 7.7cm 1896 n/a. In 1897 the APK contacted the Krupp company to develop a howitzer with a recoil system. A number of types were under development to meet this request. With this development in progress, and the fact that the General Inspectorate of Foot Artillery wanted the replacement of the older fortress guns (the 15cm 1882 mortar and the long 15cm mortar 1892) with longer range pieces, it seems the climate was favorable to further develop a recoil-howitzer9. Further, this howitzer could serve both a field and fortress role. Technical details such as deletion of the 45 degree elevation requirement and setting a requirement for range of 7000 meters was worked out between the War Ministry and the General Inspectorate of Foot Artillery.10
By the fall of 1899 a request was made from Krupp for a field mobile 15cm. howitzer to be transported at a walking or trotting pace with crew mounted. I n August 1900 Krupp delivered the V.H. 1899(Experimental Howitzer 1899). This weapon was tested roughly one year and in 1901 the War Ministry placed an order for 24 V.H. 99’s with Krupp.11 The V.H. 99 was fired in field trials to compare its performance with the s.F.H. of 1893. Although the V.H. 99 met the agreed requirements it was rejected from service with the Foot Artillery. It was found to be unwieldy and awkward in a firing position. Because of its short recoil, 340mm, and its weight (tube 990 kg. and carriage 1345 kg.) its wheels sank deep into the ground. Based on test reports from the 4th Battery of the Dieskau Regiment demands were made to redesign the howitzer, to making it lighter, to give it a longer carriage and provide it with a traversing mechanism within the upper carriage. These suggestions led to the “lighted howitzer” which was subsequently approved for service and designated the s.F.H. 1902 on 18 June 1903. Afterward it was gradually issued to field and fortress batteries. Many of the performance characteristics of the V.H. 99 are present in the s.F.H. 1902 including its maximum range of 7450 meters. However, the weight of the breech was reduced by 186 kg. and the carriage weight by 155 kg. from that of the V.H. The length of recoil was increased from 340 mm. to approximately 650 mm.12 The s.F.H. “02 was also provided with a traversing mechanism which allows 4 degrees of movement. The elevating mechanism will allow movement from 0 to 42 degrees.13 The “02 is sighted by a dial/optical indirect fire sight. Some pre-war pieces also have a crude metal direct fire sight. Wartime production “02’s do not have this sight or the pre-war ornamental scroll work. The trail is considerably longer than the s.F.H. of 1893 and the V.H. 99. Consequently one man can pick up the howitzer at the lunette. This is not possible with the s.F.H. “93 and is in fact difficult with two men even using levers. The wire-rope and brake pad system for the “02 was generally the same as that on the “93. This allows the brakes to be applied when traveling, using cords pulled by crewmen ridding on the limber, or before firing simply by hand. The effectiveness of this new howitzer was also improved by the introduction of the 15cm. 04 shell, which has a shell weight of 40.5 kg. and a delayed-action fuze for penetrating covered entrenchments.14 Improvements in optics, (forward observer scope), communications (field-phones), and magnetic dial-type aiming circle with an optical scope improved the efficiency and accuracy of the Foot Artillery in field service. It is important also to note that all of these improvements were retrofitted to the older s.F.H. “93 which continued in service in large numbers.
Participation in tactical maneuvers as well as live fire exercises utilizing forward observers greatly enhanced the effectiveness of this new arm. Almost as important this efficiency was gaining the acceptance and respect of the maneuver forces. 8 August 1906 Kaiser William II addressed his officers following a live fire exercise at Wahn. In part saying “There is no doubt that the infantry and the field artillery, that are confronted with such targets as they have engaged today, will breathe a sigh of relief when their heavy shells hit the enemy lines, and that the spirit of advance and a grateful feeling towards heavy artillery will pervade them.” Dedication for maintaining and increasing performance standards could be seen in annul “Kaiser’s Shooting Completions”. To meet the standard, s.F.H. “02 batteries would take 17 to 18 minutes to emplace and lay their howitzers and would then fire 100 shots at two targets. One target would represent an enemy battery 5000 meters distant and the second an entrenched infantry position 4500 meters distant. The battery undergoing evaluation would not receive their “call for fire” until the howitzers were unlimbered.15
In France the s.F.H. 1902’s counterpart was developed. It had 6000 meters range with 3200 kg. weight in firing position, 1164 kg. heavier than the “02. Despite being marginally less mobile the French Rimailho howitzer was a good match for the “02.
Below: 15cm. s.F.H. 1902 with two caissons and crew.
It is astounding to note that in the face of this development France chose to reject heavy-recoil howitzers for field service. Showing the influence and mindset of the maneuver commanders. With the exception of the 65mm Schneider-Ducrest Model 1906 mountain howitzer and the Colonial Service mountain howitzer 70mm S.A. St.- Chamond the French also rejected light field howitzers from service. Strangely, the advantages of the howitzer were seen in mountainous terrain but not in what was expected for the regular field army. What part of Western Europe does not have hills and defilades? What infantryman does not have an entrenching tool? It was felt that all fire support needs could be met by the flat trajectory of the 75m Mle 1897 field gun. This error was one of many that cost France much in lives and real estate. In 1914 all of Belgium and much of France was lost, 955,000 French troops quickly fell or were captured, with nearly two million in 1915. France was clearly beaten back by a far superior enemy. Much has been made of the obvious differences in their infantry tactics, but one of the main material and technological differences in the two forces lay with their artillery. It seems probable that the French themselves recognized their error following the tremendous losses of 1914. They spent the remainder of the war trying to match the German heavy howitzer technology and tactics.
Before the war interest grew in Germany for a heavy field howitzer with a shield. This required that the howitzer remain steady when firing. Otherwise, the crew could not stay covered behind its armor during recoil. Tests the APK conducted using loose shields, placed beside the howitzer, had failed. They had not been able to stand the strong muzzle blast generated upon firing. The weight of this extra armor also made them impractical to carry along and emplace. To provide steadiness during firing it was necessary to increase the length of recoil. In 1907 the APK was determined to propose a new 15cm howitzer with a protective shield. However, this created much controversy. The same old argument flared up again as to whether, after the introduction of the light field howitzer (l.F.H. 98/09) another heavy field howitzer was necessary.16 Yet another group, among them representatives of the General Staff, wanted to have an intermediate caliber 13.5cm “common howitzer” in place of a 10.5cm. and a 15cm. combination. This group felt justified by reports presented during the introduction of the new 15cm. 04 shell. It was reported that the 04 shell had more than enough power when used against troops dug in with cover. From this report the General Staff concluded that a reduced caliber howitzer should be adopted. New tests were, however, necessitated by the recently introduced Field Fortification Regulation of 1906. Improved stronger shelters were required in these regulations, which called for a double layer of rails and an intermediate layer of earth, rails, logs or ballast.17 For several months firing test were conducted at Kummersdorf with 13.5cm. and 15cm. howitzer shells. This task consumed great amounts of ammunition due to the fact that direct target hits were required. The coverings constructed according to the 1906 Regulations were not penetrated by the 15cm. 04 shell. A 40 kg. shell with a 6 to 7 kg. explosive was found to be necessary to achieve effects on covered shelters. The same conclusion was reached as in the 1891 test between the 12cm. and the 15cm. howitzer shells. A 13.5cm. shell would have to be much to long to carry the necessary explosive charge, and accuracy would suffer. From 1908 to 1910 additional tests were conducted to determine effects on field coverings. The target shelters tested were 50 cm. concrete on wooden or earth pad; 60cm. reinforced concrete; 80cm. gravel concrete on T-girders; 1.08 m. concrete, special mixture on double rails; 1. m. gravel concrete on corrugated sheet metal; 80cm. ballast concrete, set for 14 days. 15cm. shells with explosive charges form 5.5, 6 and 8.2 kg. base fused with hardened noses were even unable to penetrate any of these coverings. These tests proved the need for 21cm. shells when concrete shelters over 50cm in thickness were targeted.18 The 21cm. shell’s effects ended at a concrete thickness of 1 meter if single round penetration was required. The tests were carried on using shells of larger caliber up to the 42 cm. mortar, and afterwards test were conducted to determine the effect of large explosive charges. These tests formed the basis for the list of norms or something like our Joint Munitions Effectiveness Manual for high angle howitzers.19
In a report dated 17 December 1908 the APK presented design requirements for a new 15 cm. howitzer. It was specified that weight of the gun in firing position should not exceed 2100 kg. and in traveling configuration 2700 kg. Mobility should at least equal the s.F.H. “02. The howitzer was required to have a range of 8000 m. with projectile weight of 40 kg.20 Shield thickness of 3 mm. and height from the ground of 2 m. was required. The howitzer was to remain at rest when fired with the smallest charge at an elevation of 0 degrees and when all charges are used from about 18 degrees. Carriage length from the axle to the tip of the folding spade should be no more than 3.3 m. Range of elevation should be 0 degrees to 45 degrees and traverse at least 2.5 degrees to each side. Required also was a sighting arrangement with traversing and elevation wheels accessible to one crewman. Seats for number 1 and 2 gunners for sitting in firing position and common ammunition with the s.F.H. of 1893 and of 1902 was required. The wheels were expected to be interchangeable with those of the limber. It was considered preferable that the limber accommodate at least two rounds.21
After gaining approval of the General Inspectorate of Foot Artillery and the General staff, the War Ministry gave an 11 February 1909 dated order for one test howitzer each from competing firms. The 17 December 1908 report served as the basis for this order, which went to Krupp, Heinrich Ehrhardt’s Rheinsche Metallwaren und Maschinenfabrik A.G. (Ehrhardt was a Rheinmetall official so it appears the two names are almost used interchangeably) and the A.K. As is clearly the pattern, this order provoked controversy. Those opposing the new s.F.H contended that no heavy howitzer was needed alongside the new shielded 10.5 cm. l.F.H. 98/09 and the direct fire 7.7cm. l.F.K. In response, the Inspector General of the Foot Artillery, General von Dulitz, commented “In field warfare, the artillery must keep the enemy field artillery at bay of the infantry, otherwise a large portion of the artillery is superfluous.” General von Dulitz also pointed out that the shrapnel shells of the 7,7cm. light field guns were useless as counter battery weapons against enemy shielded batteries and were of no value in their task to "keep the enemy field artillery at bay". Despite the test which had proven the 15cm. over the 13.5 cm. at Kummersdorf, more tests were ordered to determine the effects of light and heavy howitzers on shielded batteries. The test firing took place at Jueterbog in October 1910 and was based on both howitzer types having the same amount of ammunition in terms of weight. With the given ammunition the 10.5 cm.’s effects covered roughly two targeted battery positions. The 15 cm.’s effects covered between three to four targeted battery positions.22 Even with the better performance of the 15 cm., effects were considered impressive enough form the 10.5 cm. that both howitzers were concluded to be necessary. The upshot of this was, however, that the 15cm. heavy field howitzer concept proved itself yet again. Despite commanders complaining of march columns unnecessarily long, and movement too slow to keep up with the troops, heavy field artillery stayed and was developed in Germany. In France no parallel survived the fervor to re-fight the Franco-Prussian War. Participation of heavy field howitzer battalions in prewar firing exercises and maneuver field training exercises helped dispel some of these misgivings. However, grumbling of this nature could be heard from maneuver and “light” field artillery commanders right up until the war. Once the reality of combat in the Twentieth Century was seen these attitudes changed.
On 23 February 1911 the Rheinmetall test howitzer was accepted for field trails. The Krupp howitzer was over the weight requirement and was not presented. Professor Rausenberger of Krupp felt there was much work to be done to satisfy the requirement that the howitzer remain at rest at an angle of eighteen degrees, firing the strongest charge. At their own expense Krupp built three new experimental howitzers. In January 1911 these were presented to the APK. 23 The first had constant recoil, back positioned trunnions, equilibrator and recoil brake above the tube. The second had variable recoil and the third had constant recoil without an equilibrator. The first howitzer was accepted on the basis of the order placed in February 1909. It was designated Krupp Test Howitzer. A Rheinmetall design was also accepted for test and competed along side the Krupp in firing and travel testing in the Westerwald area.24 In firing test the Rheinmetall design proved superior, however, because of the mobility controversy weight was the primary concern for the APK.
The Rheinmetall test howitzer had variable recoil and fully used its recoil length of 1600 mm. opposed to the Krupp’s 1200 mm. constant recoil. Both howitzers had grown heavier than 2100 kg. and had firing ranges of about 9250 m. Ehrhardt’s Rheinmetall howitzer featured a loading lever, which allowed the tube to move into loading position without interrupting laying. Both had spring recuperators even though the APK continued to test an air recuperator at Kummersdorf, should it become necessary later.25
On 21 May 1912, after the preliminary conclusion of the firing and traveling test, an order for a test battery comprising four howitzers was placed with Krupp and Rheinmetall.26 The requirements for this battery were generally identical with those for the Test Howitzer. Regarding the Krupp several important exceptions were noted, however. The recoil brake was to be positioned below the tube; maximum possible stability for all tube elevations was expected when firing normal charges. Following firing test in Russia, Krupp engineers concluded a combination of their back-positioned tunnions with equilibrators and the Rheinmetall style variable recoil would best met the requirements.27 To meet these demands Krupp suggested that this test battery should be constructed with back-positioned trunnions used in combination with a variable recoil mechanism. The APK agreed with these suggestions and the battery of test howitzers were accepted for firing and maneuver test in February 1913. The two firms delivered one howitzer each to Foot Artillery Regiment 14. This regiment used them in the autumn maneuvers and submitted a report to the General Inspectorate of Foot Artillery (Stassburg, 30 September 1913). This report emphasized the importance of reducing the howitzer’s weight.28
The report of the 14th Regiment gave the following weights:
|Krupp howitzer no. 6
||2160 kg. in firing position
|Rheinmetall howitzer no. 2
||2215 kg. in firing position
|Krupp how. No. 6 ready to move
|| 448 kg.
|Rheinmetall how. No. 2 ready to move
Less than one hundred kg. difference in weight turned
the decision in favor of the Krupp Test Howitzer and on 22 November
1913 the AKO (Supreme Cabinet Order) introduced this design as the s.F.H.
1913. Upon this announcement it was also mentioned that the s.F.H.
1913 was considered a cooperative effort between Krupp and Rheinemetall.30
Presumably because much of the development of the variable recoil was
accomplished on the Rheinmetall side of the house this credit was given
by the APK. Krupp protested this statement, contending that they
had pioneered the variable recoil system.
An initial order for 360 s.F.H. “13’s was promised
to Krupp, of which 48 were to be delivered by October 1914. Upon
the outbreak of the war, the first of these were almost completed and
were in a short time fielded.31
Krupp along with other contractors, such as Rheinmetall and Spandau,
produced large numbers of these weapons during the war years.
The “13” has a carriage much like the s.F.H.”02,
however, its spade could be fitted with a trail plate, which stopped
the spade’s blade from digging in more than necessary. This
plate was secured on brackets between the trail box and the opening
in the box trail. Its sight is fitted with a range drum, which
determines quadrant elevation. To the front of the trunnions are
two spring equilibrators. A shield is fitted to the howitzer and
a hinge allows the top to fold forward. A hood protects the area
between barrel and the barrel cut out in the shield. This hood
has a notch through which a simple direct fire metal sight can be viewed.
The weapon has layer and loader seats. The elevation and traversing
handles can be reached from the layer’s seat. The same short
shell casings containing a primer train are used in the “02”
and “13”. Also in the same way, bag charges and projectile
are loaded to the front of the shell case. Double acting brakes
with cables that rap around the hub and pull on a brake shoes and make
contact with the wheel tire are similar on all s.F.H. weapons.
These brakes can be operated by a man standing beside the weapon, or
remotely, by a man mounted on the limber using ropes. Scrollwork
often found on s.F.H. “02’s does not seem to be common,
probably due to the fact that “13’s” were almost all
wartime production howitzers.
Below: 15cm. s.F.H. 1913 with its crew in WW1
With the tremendous stresses put on the s.F.H. “13 design
in the early stages of the war one serious flaw was detected.
Recuperator springs failed and broke in very large numbers. Aggravating
this problem was the habit of firing batteries to over order replacement
springs to compensate for the expected problem. As a solution,
Krupp suggested fitting an air-recuperator to the s.F.H. 1913.
Its design was closely based on the Krupp air recuperator for the s.F.H.
“02, which was tested at Kummersdorf.32
After test had been conducted on an air recuperator it was introduced
in the spring of 1915 for use on the “13. With this modification,
the howitzer weight increased from 2135 kg. to 2175 kg. The recoil
which had travel from 1520 to 1030 mm., lengthened to 1565 to 1065 mm.
Elevation of 40 degrees increased to 41 degrees. Later, carriage
reinforcement was necessary which further increased the weight in firing
position to 2200 kg. and the ready to move weight of 2990 kg.
This was quite a contrast from the pre-war attitudes about howitzer
weight, when official weights were taken without paint. In the
war years 50 to 100 kg. did not matter.33
Krupp had few problems converting to air recuperator production for
the”13, and in fact were able to deliver them to field units in
an incredibly short time. Rheinmetall had greater difficulty but
were able to meet the requirements with special effort. Other
factories with out expertise with air recuperators simply had to continue
with the manufacture of the “13 with spring recuperator.34
The first battery was provided with air recuperators in June of 1915.
Interestingly, there does not seem to be a way to tell, externally,
if an s.F.H. 1913 has the spring or the air recuperator. Also
the type of recuperator does not change the designation of the weapon.
The British played out an almost identical series of events. Their 18-pounder
Mark I also suffered the wartime malady of recuprator spring stress
Generally the s.F.H. 1913 was a successful design with the total
number supplied by Krupp and Rheinmetall amounting to 3,409. Of
which, 2,676 were manufactured by Krupp and 733 by Rheinmetall.
An unknown number of “13s were also produced by other shops, such
as the Spandau in the author’s collection. Of these Herman
Schirmer’s reference notes only 252 were equipped with counterrecoil
springs and the remainder having the hydropneumatic counterrecoil mechanisms.
The level of acceptance this weapon achieved is evident in a 6 November
1917 letter sent to the Ministry of War by the Supreme Command of the
Army. In part reading “The heavy field howitzer 13 will continue
to be the mainstay of battle in this war.” Further, this letter
endorses the concept of organizing Foot Artillery Battalions with two
batteries of heavy field howitzers and one battery equipped with 10
cm. field guns. Despite these positive words there was need for
improvement and modification in the “13. Two requirements
brought about the long s.F.H. 1913 design. First, to increase
range without the use of the exceptional charge. Second, to eliminate
in-bore explosions. This weapon is essentially a long barrel variant
of the standard “13. However, the following is a list of
all changes incorporated into its design:35
||Enlargement of the shell chamber from 152 in 3 (2,5 dm.3) to 213 in3 (3,5 dm3) leading to a top charge gas pressure reduction from 34 084 psi (2350 bar) to 30458 psi (2100 bar). From the front breech face to the beginning of the grooves, the shell chamber was enlarged from 6.6 in (169 mm) to 8.3 in (211,5 mm.). The former exceptional charge was eliminated. The heavy field howitzer “13 (long) was designed for eight zone charges:
Zone charge 8 (Velocity = 377 meters per second)
Zone charge 7 (Velocity = 349 meters per second)
As a result of these modifications, the recoil force at maximum recoil motion was reduced from 11500 kg. to 11000 kg. and 18250 kg. to 17500 kg. at minimum recoil motion.
||The recoil energy was reduced by using a heavier and three calibers longer howitzer tube which at the same time helped to avoid excessive recoil fluid heating. Apart from several useful mount and carriage reinforcements it was necessary to modify the graduation drum of the sight and reinforce the equilibrator springs.
||Since the rifling of front line howitzers were damaged especially after prolonged firing, broader lands with a more favorable profile were used. Land s and grooves were enlarged from 3.5 mm. to 5 mm. and from 9.55 mm. to 9.7 mm. respectively. The number of grooves was reduced from 36 to 32.
||The initial spin was reduced from 5 degrees to 4 degrees and the exit angle from 10 degrees to 8 degrees. This led to a considerable service life increase of the tubes, and the number of in-bore explosions was minimized. These improvements led to a weight increase of about 90 kg. compared to the older field howitzer version with counterrecoil springs. (From 2110 kg. to 2210 kg. in firing position) By using a longer tube the trail pressure at 0 degrees elevation was reduced from 70 kg. to 50 kg.36
Below: This is a period photograph of a 15cm. lg.s.F.H. 1913, however, it appears this one was upgraded from an older
15cm. s.F.H. 1913. Notice under the band around the muzzle end of the barrel there is an wedge shaped connection to the
recoil cradle. There is also an example of this type of upgraded at Baltimore’s War Memorial.
(Photographs comparing a regular lg.s.F.H. "13 to one upgraded)
Due to difficulties in manufacturing the lg. s.F.H. 1913 and the limited number of facilities capable of producing a hydropneumatic counterrecoil, a variation of this design was developed by Krupp and designated lg. s.F.H. 1913/02. The most easily recognized changes in the “13/02” are removal of layer and loader seats, and the hinge across the shield. A one-piece spade and trail plate was introduced for the “13/02 to check it from digging too deeply into the earth. The loading lever was eliminated. Another important but less obvious change is the use of a hydro-spring recoil in place of the hydropneumatic type. Recoil for the “”13/02’ was permanently long with 950mm of travel and required 26 liters of fluid in the recoil brake. The carriage was reinforced to withstand the recoil forces. Interestingly, the lg. s. F. H. 1913/02 in the author’s collection has recoil springs carefully marked lg.“13/02 and numbered with the many dots of a hand punch. This would seem to indicate that despite the fact that the “13/02 was introduced to speed production, significant individual care was taken with the springs by shop workers.
Within the 25 year development time of the s.F.H. 15cm series heavy artillery progressed from having virtually no impact on the maneuver battle to the dominant force, living up to its motto "Ultma Ratio Regius". Nurturing this development was a long line of technical innovations. These include improved aiming circles (directors), and panoramic howitzer sights; use of meteorological data (MET), HE and chemical munitions, and recoil systems (hydopnumatic and hydro-spring). Development of tactics and techniques within this 25-year period surly went hand- in- hand with howitzer development. At first just the act of quickly emplacing batteries in the field and conducting indirect fire, then converging fires not just of batteries but battalions became common. Still further, coordinated fire planning supporting maneuver became a science. Much of what we know as the “fundamentals” developed around the Field and Foot Artillery howitzers of the German Army and especially the s.F.H. series. The lg"13s and new s.F.H. models went on to do the same in the Second Would War but with even greater need for mobility, which most accomplished using horse teams just as in the Great War. In the US, primarily because we were newcomers to the Great War and were quickly versed in the merits of heavy artillery (the 155mm and 60pounder) by the French and British, we see their weapons as the pioneers of this technology. We seem to have forgotten that their development was forced by the success of the German howitzers.
Below: Photograph of a 15cm. lg.s.F.H. 1913 in Third Reich service with the crewmen training for operations in a chemical warfare environment .
1 Rudolf Kuehn, Waffenlere, Heft XI: Feldhaubitzen (Wien: Kommissions-Verlang L.W. Seidel & Sohn, 1905) pages 1-3.
2 Verlag Bernard & Graefe, 1937) page 44.
3 Ibid., p.45.
4 Ibid., p.46.
6 Herman Schirmer, Das Geraet der schweren Artillerie vor, in und nach dem Weltkrieg, p.47.
7 Ibid., p.49
8 Georg Bruchmueller, Die Deutsche Artillerie in den Durchbruchschlachten des Weltkrieges, ( Berlin: Mittler & sohn, 1922) p8 break through battles
9 Herman Schirmer, Das Geraet der schweren Artillerie vor, in und nach dem Weltkrieg, p.52.
10 Ibid., p.53.
12 Ibid., p.54.
15 Ibid., p.55.
16 Ibid., p.56.
17 Ibid., p.57.
18 Ibid., p.58.
20 Ibid., p.59.
21 Ibid., p.59,60.
22 Ibid., p.60.
23 Ibid., p.61.
24 Entwicklung des Artilleriematerials im Weltkriege, (Fried. Krupp, Essen.) p.123.
25 Herman Schirmer, Das Graet der schweren Artillerie vor, in und dem Weltkrieg, p.61.
26 Ibid., p.62.
27 Entwicklung des Artilleriematerials im Weltkriege, p.62.
28 Herman Schirmer, Das Geraet der schweren Artillerie vor, in und nach dem Weltkrieg, p.62.
29 Ibid., p.63.
31 Entwicklung des Artilleriematerials im Weltkrieg, p.123<
32 Herman Schirmer, Das Geraet der schweren Artillerie vor, in und nach dem Weltkrieg, p.66.
33 Ibid., p.67.
35 Herman Schirmer, Das Geraet der schwereen Artillerie vor, in und dem Weltkrieg, p. 69.