Shooting the War

The German Super-Guns of the WWII

The German super-guns
The heaviest field equipments seen during the war were the German self-propelled howitzers generically known as ‘Karl Morsers’. These were of two calibres, 540-mm and 600-mm, mounted on the same type of carriage. Six carriages were made and the exact disposition of barrels between them is in some doubt; the carriages were numbered I to VI; Vehicle V was captured by the US 1st Army and found to have a 540-mm barrel, yet photographs captured later showed this same carriage to have a 600-mm barrel. It is probably safe to assume that three of each calibre were made. The date of introduction is also a little vague, but it seems fairly certain that the 600-mm version was introduced in 1942 and the 540-mm in 1944.
The carriage of ‘Karl’ was a simple rectangular box, divided into three compartments. The first held the Mercedes-Benz engine and transmission; the second carried the gun; and the third held the carriage raising and lowering gear. After driving into position on its tracks the engine was used to drive the lowering gear, which rotated the anchorages of the suspension torsion bars so as to allow the chassis to be lowered to the ground until the suspension and track were relieved of the weight. For long-distance moves the gun and recoil system were removed from the carriage, dismantled, and loaded on to spec,a -,a e•s, the carriage was then winched on to a special tank-transpor-er. For very long distances the complete gun and carriage assembly could be slung between two railway flat wagons by means of special trusses.
In the use of railway artillery Germany virtually had the field to herself. This class of weapon is really the prerogative of the Continental nation with a well-developed rail system by which it can readily deploy them to any front. In contrast, Britain and the USA, while possessing railway guns. used them solely as mobile coast defence units, since the problem of transporting two or three hundred tons of railway mounting across the Channel was not a trick to be undertaken lightly. Indeed, the British and American weapons were almost entirely relics of the First World War which had been in mothballs. 1940 saw a few more mountings hastily cobbled together from available spares and hurried to cover the Channel, just as in similar fashion American guns were mobilised and deployed in 1941. In 1944 reports from France indicated that heavy railway artillery might be of use in demolishing strongpoints to be expected in the final assault in Germany, and designs were hastily prepared by the Americans for a number of 16-inch guns, but within a few weeks it was seen that heavy artillery of this class had been rendered superfluous by the quality and quantity of air support available, and the demand was cancelled.
The German army had a vast range of railway guns from 150-mm upwards, but two were really outstanding and deserve closer examination. The first was the 28-cm K5(E)—Kanone, Model 5, Eisenbahnlafette —which became their standard super-heavy railway gun and was probably the finest design of its k;nd in the world. The basic arithmetic and paperwork had been done in the late 1920s and early 1930s, and work began on the gun in 1934. (It is worth noting that every German railway gun was designed and built by Krupp— Rheinmettal did design two, but they were never made.) First, a 150-mm barrel was produced for tests; it had been decided that to obtain the great range demanded, a conventionally rifled barrel was out of the question. A design was prepared with 12 deep grooves and having a shell carrying 12 ribs, or splines, to match. The theory behind this was that the engraving of a conventional copper driving band on the shell gave rise to very high pressure in the gun chamber; by using the spline and groove method to spin the shell, this resistance was removed, and the shell would step off more smartly, allowing a bigger propelling charge to be used without over-straining the gun. The 150-mm test barrel proved that the theory was right, and a full-calibre 280-mm barrel was built.
The mounting was a simple box-girder assembly carried on two six-axle bogies, with the front bogie slung so as to allow the front of the box-girder to be swung across it for aiming the gun. For large angles the whole weapon was mounted on a special portable turntable built at the end of a short spur of track laid at the desired firing point. Each gun was supplied with a special train which included wagons for carrying the turntable, light-antiaircraft guns for local defence, air-conditioned ammunition wagons, living quarters and kitchen for the gunners, and flat wagons to carry their entitlement of motor transport.
By 1940 eight of these complete equipments were in service, and production continued throughout the war, 25 being built in all. The German gunners called them ‘Slim Bertha’, but to the Allies in Italy one at least became famous as ‘Anzio Annie’.
With the 561-pound pre-rifled shell the gun could reach to 68,000 yards. A rocket-assisted shell was later developed which increased this range, with a certain loss of accuracy, to 94,000 yards. Finally, the Peenembride Research Establishment designed a 300-pound dart-like projectile which was fired from a special 310-mm smooth-bore barrel and which ranged to 170,000 yards. Although coming too late for general issue, these ‘PeenemOnde Arrow Shells’ were issued for troop trials in the field, and some were fired against the US 3rd Army at ranges of about 70 miles.
The second railway gun, ‘Gustav’, was the biggest gun the world has ever seen —the Krupp-designed 800-mm Kanone. The idea was conceived in 1937 of a pair of super-guns; they were of quite conventional design, except for their immense size. Too large to be moved in one piece, they were transported piecemeal in special trains and assembled at the selected sites by travelling cranes. When assembled, the mounting straddled two sets of standard-gauge rails, with 80 wheels taking the 1,350-ton weight. An armour or concrete-piercing shell of 7 tons was propelled by a 13/4-ton charge to a range of 23 miles, or a 5-ton high-explosive shell to 29 miles. The first equipment, ‘Gustav’, was proved at the Rugenwalde range in March 1943, in Hitler’s presence. The only record of its use was at the siege of Sebastopol; the gun was sited at Bakhchisary and fired some 30 to 40 rounds. One shot is recorded as having penetrated through 100 feet of earth to destroy a Soviet ammunition dump at Severnaya Bay. The subsquent history of the gun is unknown (it was presumably captured by the Red Army).
The second equipment, ‘Dora’. so far as is known, never left the proving ground, though what happened to it at the end of the war is a minor mystery (some ammunition and a spare barrel were found at Krupp’s proof establishment at Meppen near the Dutch border).
The detachment necessary to man. maintain, and give local protection to Gustav was 4,120 men strong. commanded by a major-general. The actual fire-control and operation of the gun demanded a colonel and 500 men, and the construction or dismantling of the weapon took between four and six weeks. A long-range ‘PeenemOnde Arrow Shell’ was developed for Gustay. but, so far as is known, was never fired. This was to weigh 2.200 pounds and range to 100 miles. There was also a proposition to mount a 520-mm gun on the same carriage to fire rocket-assisted shells and ‘PeenemOnde Arrow Shells’ to a range of 118 miles for cross-channel bombardment, but this never got past the drawing-board.
If it is accepted that it is not a good idea to tamper with a good gun design in the middle of a war, then the only way to render the gun more effective is to improve the ammunition, and this technique was frequently adopted during the war. And in no field is this seen to greater effect than in the battle against the tank. The reason for this is fairly self-evident: personnel targets remain more or less the same—once the anti-personnel projectile is perfected it can stay as it is. On the other hand, once a new anti-tank projectile appears, it is only a matter of time before the enemy put thicker armour on his tanks.
At the outbreak of war there were two types of anti-tank projectile: the armour-piercing (AP) shot, and the AP shell. The difference is basic. Shot are solid, with no explosive filling, and rely purely on their speed to smash through the armour and do damage inside the tank by their impact, the fragments of plate they knock off during penetration, and their own effect when they penetrate the plate and bounce around inside the tank. AP shells, on the other hand, have a small cavity filled with high explosive and are fitted with a fuse in the base. The shell penetrates, similarly to shot, by brute force, but the fuse is activated by the impact and, after a short delay to allow the shell to pass through the plate and enter the tank, the explosive is detonated, shattering the shell into fragments and adding to the shot-like damage already caused. On paper the shell is the better proposition, since there is the bonus of the explosive filling. But paper figures tend to be deceptive, and in fact the shot is probably the more practical projectile, because the high-explosive (HE) cavity weakens the shell, and the fuse is precariously supported against the hammer-blow of impact. Britain held firmly to the shot theory for anti-tank work, though many years of experience in producing AP shells for naval use was available. Several other nations preferred AP shell, bewitched by the HE bonus.
Most of the belligerents entered the war with a plain shot or shell and relied on throwing it hard enough to penetrate the opposing tanks. So long as the target was relatively lightly armoured this was successful; but, naturally, each side began to increase armour thickness on each succeeding generation of tank. The quick answer to this was to increase the gun charge or even the calibre, and thus throw the projectile harder, but there comes a time when the impact is too much for the projectile, and instead of piercing, it merely shatters on the outside of the target without doing any damage.
The answer to this was to protect the tip of the shot or shell with a softer cap, which tended to spread the impact stresses over the shoulders of the projectile, instead of concentrating them into the tip. This preserved the piercing action to higher velocities, and the gun was again winning the battle. The next move belonged to the tank designers who made their armour thicker, and so it went on until the projectile was once more shattering, cap or no cap. At this point the projectile designers were faced with a new problem: if it was futile to throw the projectile harder, might it not be possible to throw a harder projectile? And what was harder than an armour-piercing projectile? Tungsten carbide, a diamond-hard alloy, provided an answer, but it was about one-and-a-half times as heavy as steel, so that it could not easily be made into a projectile. Furthermore, it was expensive and in short supply.
The first application of tungsten to an anti-tank projectile was by the German army in their 28-mm Schwere Panzerbuchse 41, a weapon with a unique tapered barrel. The shot consisted of a small core of tungsten carbide held in a light alloy casing of 28-mm calibre. As the shot was fired down the gun barrel, so the calibre diminished and the light alloy casing was ground down, until it emerged as a 21-mm shot. This squeezing enhanced the velocity and changed the ratio of shot diameter to weight. The velocity reached was 4,000 feet per second, and, on impact with the target, the hardness of the core was impervious to impact shock and penetrated successfully.
About the same time—late 1940—a similar idea had been put forward by a Mr Janacek, a Czechoslovakian weapon designer working in England. While his idea was still under consideration, a specimen of the German weapon was captured in North Africa and flown home for trials: the idea was seen to be feasible. The British version was in the form of a taper-bore adapter to be fitted to the existing 2-pounder gun, together with a special tungsten-cored shot, known under the code name of ‘Littlejohn’, an Anglicised version of Janacek. The advantage here was that the adapter could be removed to permit firing normal explosive shells, but could be refitted quickly for the special shot, whereas the German design required a special pattern of high-explosive shell to be developed, a difficult feat in such a small calibre. The ‘Littlejohn’ attachment and its shot were not used in towed artillery, since by the time they were ready for service the anti-tank units were armed with 6-pounders, but it was used on 2-pounder and American 37-mm guns mounted in armoured cars.
To use tungsten in a conventional gun, a different approach was needed. The first attempt, for the 6-pounder, was the ‘AP Composite Rigid’ (APCR) shot, a tungsten core mounted in an alloy sheath of approximately the same dimensions as the conventional steel shot for the gun. By virtue of its light alloy content the APCR shot was somewhat lighter and thus had a higher velocity when fired. Unfortunately the ratio of weight-to-diameter was unfavourable, giving a poor ballistic coefficient or ‘carrying power’, and while the short-range performance was impressive, the velocity soon dropped, and at ranges over 1,000 yards, steel shot was just as good, sometimes better. Some German weapons were also provided with the same type of projectile, and one was designed for use in the Soviet 76.2-mm field gun which the Germans captured in large numbers and converted into an anti-tank gun. Unfortunately for them, by early 1942 the shortage of tungsten in Germany began to be felt, and in the middle of that year a ban was placed on the use of tungsten in ammunition; what scarce supplies there were had been earmarked for machine tool production, not for throwing about the Russian steppes. After strong remonstrations, the 5-cm Pak 38 anti-tank gun was specifically exempted from this ban, since at that time it was the only weapon capable of stopping a Russian T-34 tank, provided it was supplied with tungsten-cored shot.
Although the 6-pounder APCR shot seemed reasonably successful, it was not the ideal answer. The ideal, in fact, sounded ridiculous: what was wanted was a shot which in the barrel was large-calibre and light, so as to pick up speed quickly and leave the gun at high velocity, but which outside the barrel should be small in diameter and heavy, so as to have good ‘carrying power’ and keep up its high velocity for a long range. These two conflicting requirements were fused into one projectile by two British designers, Permutter and Coppock, of the Armaments Research Department. Even before the 6-pounder had received its APCR shot they were at work, and in March 1944 their ‘AP Discarding Sabot’ shot was provided for the 6-pounder. In this design, the tungsten core is contained in a streamlined steel sheath or sub-projectile; this in turn is carried in a light-alloy framework or ’sabot’ of the full gun calibre. On firing, this sabot holds the sub-projectile centralised in the bore and gives the whole thing the combination of light weight and large area which is wanted for velocity. But firing actually ‘unlocks’ the sabot, and as the shot leaves the gun muzzle, so the sabot is thrown clear, allowing the sub-projectile to race to the target at velocities of the order of 3,000 feet per second. Now, since the sub-projectile’s sheath is virtually a skin round the tungsten core, it follows that the weight is high in relation to the cross-section—the ideal condition for good carrying power and thus long-range performance. A similar projectile for the 17-pounder followed in September 1944, and one was under development for the 20-pounder tank gun when the war ended.

German, French, British, American and Russian Guns of the WWII

As with the tanks, so with the guns: the artillery designers of the
Second World War found themselves caught up in a ceaseless race
to outmatch the ever-improving enemy defences. Ian Hogg shows how
this affected the gunners’ war, and how it resulted in the artillery
revolution of greater ranges, mobility and fire control.

A thorough discussion of the history and development of every artillery weapon used in the Second World War would need several volumes, for the sheer size of the subjects is incredible; the German forces alone disposed over 200 land service weapons in 51 different calibres, without considering experimental models. Britain and America between them fielded about 100 artillery weapons, again not counting experimental models but only those which found their way into the hands of troops. Instead of trying to catalogue every weapon used, therefore, this section merely outlines the principal features of the research which developed during the war, and also brings to light one or two of the more unusual and less well-known weapons which were produced.
There are three main subjects to be explored:
•    The routine improvement of weapons, in order to bring them into line with changing tactics and concepts of employment or to counter improvements in enemy defences;
•    The improvements in ammunition introduced to step up the performance of existing weapons;
•    The application of hitherto untried scientific principles.
In many cases these topics tend to overlap, but rather than try to develop a chronological story with these three aspects jumbled together, it is best to consider them as separate fields.
First, routine improvement. A good example of this in action is the history of the celebrated German 88-mm Flak Gun. This was originally conceived in the late 1920s by Krupp designers attached to the Bofors Company in Sweden. When in 1931 they returned to Essen with the design, the political climate seemed right. A prototype was built in 1932; and due to thorough paperwork it was an immediate success and was issued in 1933 as the 8.8-cm Flak Model 18. It should be stressed, in view of the exaggerated tales which became current in later years, that there was nothing unorthodox about this weapon at all—it was simply a good, sound, conventional anti-aircraft gun. It was taken to Spain by the Kondor Legion during the Civil War and tested in action; its potentialities as an anti-tank gun were also seen, though not advertised. This experience showed that there were a few weak points in the design and as a result, minor modifications were made in the mounting to improve stability and facilitate mass-production. This modified version became known as the Flak 36. In the following year an improved sighting and fire-control system was fitted, and the gun became the Flak Model 37. The 36 and 37 remained in service throughout the Second World War, being used in their primary role as an anti-aircraft gun; as an anti-tank gun, when fitted with shields and direct-fire sights; fitted to coastal craft and U-boats; used as a coast defence gun; and even mounted on a 121/2-ton half-track as a self-propelled gun (though this was not one of its most successful applications).
By early 1939 though, in spite of its excellence, it became obvious that bombers were going to fly faster and higher than before, and the gun’s performance would have to be improved. And so in 1939 Rheinmettal-Borsig were given a contract for an improved model, to be known as the Flak 41. Prototype trials began in 1941 and it was found that the gun, although a most efficient design, had a lot of teething troubles which were going to take time to eliminate. Since no one else had a contract for the gun, the Luftwaffe (which was responsible for Germany’s anti-aircraft defences) was forced to use it or else do without. Consequently the next year saw a great deal of effort thrown in and by March 1943 the first issues were made.
The Flak 41, as finally produced, was a considerable improvement over the 18, 36, and 37. By using a turntable to carry the gun, instead of the more usual pedestal mounting, a much lower silhouette was achieved. The muzzle velocity and ceiling were both improved by adopting a more powerful cartridge, and the stability in action was excellent. The only fly in the ointment was the difficult extraction of the fired cartridge case, which is a flaw of major proportions in a quick-firing anti-aircraft gun. Different designs of barrel were produced in an effort to overcome the trouble, and a special brass cartridge case was developed; but none of these palliatives made much impression and the gun was never the success it might have been.
Some time after Rheinmettal had received their contract, a similar specification had been given to Krupp. Their development, sometimes referred to as the Flak 42, became more and more entangled with their concurrent development of 88-mm tank and anti-tank guns in the hopes of producing a family of weapons which would use interchangeable parts and common ammunition. Before the Krupp version had got off the drawing board, the Luftwaffe was demanding more performance than the design could produce, and in February 1943, not without a certain amount of relief, one feels, Krupp dropped the Flak 42 to concentrate on the tank and anti-tank weapons.

While the 88 shows an example of improvement of a particular calibre, the more common approach was to improve a particular class of weapon by raising the calibre; most anti-tank weapons display this technique. The British army began the war with a 2-pounder; followed it by a 6-pounder and then a 17-pounder; and finally had a 32-pounder in preparation when the war ended, having toyed briefly with a possible 55-pounder. America began with a 37-mm, took over the British 6-pounder and called it the 57-mm; then moved to a 3-inch based on a redundant anti-aircraft gun; then a 90-mm, also based on an AA gun, and was working on a 105-mm when the war ended. Germany also began with a 37-mm and progressed through 28, 42, 50, 75 and 88-mm to arrive at a 128-mm as the war closed.
All these series show steady progression in conventional guns, ally intended to beat the forthcoming increases in enemy armour. However, the flaw in this system becomes apparent on looking at the British 32-pounder or the German 12.8-cm Pak 44— bigger calibres may mean a bigger punch, but they invariably mean bigger guns as well, and this means more weight to move about. This is a considerable drawback for an anti-tank gun which usually has to be emplaced by manpower, and certainly the 32-pounder was too big for its task; even had the war continued, it is doubtful whether it would have been accepted into service.
Anti-aircraft guns tend to show a similar pattern among all nations, always striving to extract more ceiling and greater velocity; the increased ceiling meant that higher-flying aircraft could be engaged, while higher velocity meant a shorter time between firing the gun and the shell arriving at the target, and hence less room for error in the prediction of the target’s position at the time of the shell’s arrival. The two groups of anti-aircraft weapons in common use were the light guns, such as the German 37-mm and the British and US-employed Bofors 40-mm, and the heavy guns, such as the German 88, 105, and 128-mm guns, the British 3.7-inch, 4.5-inch, and 5.25-inch guns, and the American 90-mm, 105-mm, and 120-mm types. The light guns relied on throwing up a heavy volume of fire at a high rate, to counter the low-flying attacker. The heavies fired at slower rates, threw heavier shells, and had higher ceilings to deal with the high-level bomber. But strangely enough, all the combatants had a gap in their defences, which lay between the maximum ceiling of the light guns—about 6,000 feet—and the minimum effective ceiling of the heavies—about 10,000 feet. Below this figure the heavy gun could not swing fast enough to follow a fast low flyer. In an endeavour to fill this gap, development took place in both Britain and Germanyto provide a medium AA gun. As far as Britain was concerned, a paramount feature of any weapon proposed in 1940 was to avoid usurping production already hard at work with the more basic weapons needed for simple survival. In view of this, the first question the designers asked themselves was: ‘What existing gun can be worked over to fill the bill?’ After a few false starts the design coalesced around The existing coast artillery 6-pounder gun, the same calibre as the anti-tank gun but using a heavier cartridge and capable of greater range. This was adapted to a twin-barrel mounting on a three-wheeled trailer, and work then began on designing a suitable automatic feed system to get the rate of fire thought necessary, and a fire-control system to put the shells where they were needed. Since the guns were originally designed for hand loading, the adaptation to autofeed turned out to be more difficult than had at first been imagined; then Allied air superiority gave the project less priority; and, in the event, the twin 6-pounder never entered service and Britain never had a medium AA gun.
The German development was not restricted to an existing weapon, since the ‘gap’ had been appreciated before the war, and in 1936 Rheinmettal was given a contract to develop a 50-mm gun. This was eventually introduced in 1940 in limited numbers for an extended troop trial to assess whether such a weapon was desirable and whether the Flak 41, as it was known, would fill the requirement. For a variety of reasons the gun was not a success, but the experience showed that the medium AA gun was needed, and a great deal of thought went into the design of a completely integrated weapon system, probably the first such system to be conceived as a complete entity. It was to comprise a 55-mm automatic gun, with matched radar, predictor, displacement corrector, and full electro-hydraulic remote control of a six-gun battery. By the time all these theories and designs had been put together it was mid-1943, and the production of such a far-reaching concept was so difficult that the war ended before the weapon was completed. To act as a stop-gap, the now-obsolescent 50-mm anti-tank gun was fitted with an automatic loading system, but this idea fell by the wayside, and it is doubtful if any were ever made. All in all, the medium AA gun story is remarkable in the similarity of British and German experience.

In the field artillery world practically all development was simply a matter of improvement on existing designs. No nation in its right mind would attempt a major re-equipment of its standard weapons in.the middle of a war. The British 25-pounder served valiantly, and modifications to meet special demands included the self-propelled ‘Bishop’ (on a Valentine chassis) and ‘Sexton’ (on a: Ram chassis); the Australian-developed ‘Short’ or ‘Baby’ 25-pounder with a truncated barrel, no shield, short trail and castor wheel for easy manoeuvring in the jungle; it was tried as a self-propelled gun (SP) in many vehicles including the Lloyd carrier, which was asking too much of such a light vehicle; it was strapped to the cargo bed of a DUKW for supporting amphibious landings; and it was even considered for the armament of submarines. Similarly, the American 105-mm howitzer was tried in a variety of SP mountings, starting with a half-track, until the Sherman-based M-7 became standardized as the ‘Priest’; it was shortened and placed on a light carriage for use by airborne units; it was mounted in tank turrets as a close support gun; and, like the 25-pounder, mounted on the long-suffering DUKW.
The German 1E FH 18, more or less the equivalent of the 25-pounder and 105 howitzer, suffered similar, though more drastic, changes. First it was given a muzzle brake and a heavier charge with a long-range shell; then in an attempt to reduce the weight, like the ‘Baby 25-pounder’, the barrel and recoil system were mounted on the carriage of the 75-mm Pak 40 anti-tank gun; the wheels were removed and it was dropped bodily into a tank hull to provide an assault gun; it was grafted on to a variety of tracked mountings. But eventually a complete re-design was called for and Rheinmettal was given a contract. Before their offering was ready, the experiences of the Russian Front had shown that certain features were mandatory in the next generation of field guns. Briefly, these were that the gun must have a good anti-tank performance for self-protection; at the same time it ‘iad to be capable of hiding in forests and firing out at high angles: the range had to be at least 8 miles without demanding special ammunition; it had to have all-round traverse, since Soviet partisans c,)uld attack from any direction; and it had to weigh less than 2.200 pounds. Now even today a designer would have a hard time meeting that specification, but in 1943 both Krupp and Skoda rose to the challenge.
The Skoda version, the 10.5-cm 1E FH 43. was most ingenious: the carriage had virtually a normal split trail at the rear. plus another split trail at the front, beneath the barrel. and a firing pedestal beneath the axle. In action, the equipment rested on the two rear trails and the pedestal, and the front trails were laid on the ground to form a cruciform stable platform above which the gun could rotate through 360 degrees, the four legs giving stability at any angle of the barrel. The novelty of this carriage lay in the fact that the two front legs were not rigidly attached to the carriage; to compensate for eneven ground they were permitted to lie at any convenient angle. A hydraulic system was arranged so that slow movement of the legs—as during folding and unfolding to and from the travelling position—was freely permitted. but fast movement—as the firing shock—would cause the legs to lock rigidly to the carriage and give the desired stability.
Krupp, under the same nomenclature, produced two models; one was very similar in general design to Skoda s. though without the hydraulic system, while the other was based on a more or less conventional cruciform platform of the type familiar in AA guns. However, none of the designs, Krupp or Skoda. were ready for production before the war’s end, and only prototypes existed.