Key point: The Kaiser's huge guns were made to destroy the morale of citizens and leaders in Paris. However, these wonder weapons could not turn the tide.
World War I’s stalemate on the Western Front ushered up varied solutions. The Allies developed tanks for traversing no man’s land to get at the enemy. But tanks had faults: Artillery could stop them, so could mechanical problems and difficult terrain; and they could not get the job done without lots of infantry.
Across the trenches, Germans had little regard for tanks and produced but few models. The main effort by the Germans lay in the application of the Hutier Taktik, the forerunner of the Blitzkrieg of 1939-1940. The Hutier demanded a narrow front, advancing without regard to the security of the flanks. Follow-up troops were detailed to deal with strong points that had been by-passed. It was an approach that worked well on the Eastern Front, but less so against the entrenchments in the West because the French and British armies were more stable and because the Germans could never amass enough stormtroopers.
Germany Turns to Heavy Artillery
So from the time of the Battle of Verdun in 1916, the Germans looked to one of their strong suits: their ability to produce very heavy artillery of superlative quality.
General Erich Ludendorff, head of the Supreme War Council, was approached by naval officers commanding the very heavy guns on the Western Front (in almost all armies, large-caliber railway guns were served and maintained by naval personnel). Their proposal was to introduce guns capable of firing a shell 100 kilometers, or 62 miles. Such guns would require a heavy commitment in funding, materiel, personnel, and technological resources.
Ludendorff has been depicted as a cold, reserved officer lacking imagination. But in this instance the man immediately grasped the possibilities. At that time, Paris was only 90 kilometers, or 60 miles, behind the Allied lines and would be vulnerable to such weaponry. It was the hub of the railway network of France. It was the major industrial center of the French armaments industry and, of course, the political capital and administrative center of the French government. Ludendorff recognized an attractive target when he saw it.
He reasoned that artillery with the capacity to blast Paris might be the German answer to the horrors of the frontal assault. Instead of battering at Allied trenches, punishing Paris would be the means to destroy the heart of France; the rest of the body would wither on the vine. The lesson of Verdun was engraved on the hearts and minds of both sides. Commanders as well as fighting men were increasingly reluctant to launch a frontal assault. Thus Ludendorff was quite taken with the possibility of going over the lines instead of trying to go through them.
Dazzled by the proposed technological leap, the projected results of such massive guns were aggrandized, and the ballistic limitations were minimized. All artillery manuals contain “dispersion tables” that provide mathematical calculations of the predicted fall pattern of shells. Dispersion is caused by many factors including air temperature and density, temperature of propellant, age of launching explosive, apparent and actual wind over the trajectory of the shell, plus a host of other esoteric variables. In addition, the rule of thumb is that the higher the charge level, the greater the breadth of dispersion. Firing the charge necessary to reach Paris would engender an extreme dispersion factor. It was quite possible to hit a target the size of Paris, but pinpoint accuracy was just not in the cards. Nevertheless, German planners believed that because the French were a volatile people, the effect of Paris coming under artillery fire would be devastating.
Doing the Math
The assembly of dispersion tables is a laborious procedure requiring a tremendous number of man-hours devoted to calculations, now performed by computers. The amount of labor required to manually assemble dispersion tables is staggering, and the end product is error prone.
Dispersion is an accepted factor, and any battery servicing a target has to fire groups of shells to achieve any expectation for a respectable number to be on target. But with such long ranges as anticipated by the proposed massive guns, new complications had to be considered. The Germans would have to take into account the calculations of the French mathematician Gustave Gaspard Coriolis (1792-1843).
Coriolis had been an assistant professor of analysis and mechanics at the École Polytechnique, appointed in 1816. He had reached prominence as the result of an innovative paper published in 1815 called Theorie Mathematique des Effects du Jeu de Billards (Mathematical Theory of the Game of Billiards).
Coriolis had codified a basic principle of artillery, which was, “The angle of reflection is equal to the angle of incidence.” This proposition had been clearly demonstrated on billiard tables again and again, but extrapolating it to artillery was new. As any billiard or pool table habitué knows, a bank shot leaves the cushion at the same angle at which it arrived. Similarly, an artillery projectile will return to Earth at the same angle at which it left the muzzle.
This was not the main concern of the Germans, however. After years of diligent research, Coriolis published his true tour de force, Sur les Equations du Mouvement
In April 1915 the Germans placed extreme-range naval guns on railway mountings. These were named Lange Max (Tall Max) in honor of Vice Admiral Max Rogge, who had supervised the adaptation of naval guns for land use. With a bore of 37.99 cm (14.96 inches), these guns could loft a shell 30 miles. Firing from Lugenboom, shells were reaching Dunkerque, 23.5 miles away.
The guns were difficult to serve because the loading of a projectile and propellant, with an overall length of eight feet, could only be done from the horizontal position. Loading and relaying the guns for each firing was a labor-intensive, time-consuming project limiting the rate of fire. On the plus side, the guns were immune from direct retaliation. The Allied forces had no ability to deliver counter-battery fire, because the German guns were far out of range.
The firing site and the target were on an east-west axis, which made the projectiles virtually unaffected by the Coriolis Effect. However, Professor von Eberhardt, an obscure mathematician working for Germany’s Krupp steel and weapons corporation, had been working on a method to extend artillery range, and understood the problems that firing on a north-south axis would produce. Eberhardt was a very minor technician, and despite his prestigious “von,” his credentials and first name are unrecorded.
Krupp Sets to Work on the Big Guns
Ludendorff’s approval of the long-range artillery had set the Krupp apparatus into motion. The original specifications stipulated a range of 60 miles, later upped to 75. Krupp, probably the world’s most experienced manufacturer of artillery, began to put together such a weapon in its typically innovative fashion.
Gun barrels with a 15-inch (38.1-cm) bore were practically an on-the-shelf inventory item. The design team was aware of the barrel erosion resulting from extreme charges and approached that problem in a novel manner. An interior barrel with a bore of 8.26 inches (20.98 cm) would be inserted into the larger bore and would bear the brunt of firing. When worn down by repeated firing, the subcaliber insert could be replaced with relative ease, preserving the exterior barrel.
Nevertheless, the work was a major engineering undertaking. The gun was a composite affair, a complex assemblage produced by the renowned Krupp design teams. There was a barrel extension of 36 feet, 1 inch, forward of the original muzzle. On top of this was an additional chase (smoothbore) extension of 19 feet, 8 inches. The entire affair had an overall length of 112 feet, and a weight of 138 tons. Such a ponderous piece of artillery required external bracing to keep the barrel from sagging. Supporting the barrel was a cantilever bracing that transferred part of the load to the base of the gun. The bracing looked very much like a model of one-half of the Brooklyn Bridge. Obviously this apparatus could be carried only on railroad wheels and required the special construction of reinforced trackage.
The shell was to weight 229 pounds and was to be of novel design. Instead of using conventional copper driving bands, it would have two steel ones threaded to fit into the barrel’s rifling. Behind each driving band was a narrow copper band to act as an obduration (sealing) device. The loading drill required it to be screwed into the rifling. This mandated muscle power, and lots of it.
Krupp engineers calculated how much metal would be worn away from the insides of the barrels with each firing. They determined that the service life of the barrel was 64 rounds before rebuilding would be required. To compensate for such wear, the shells were numbered consecutively and incrementally sized to compensate for the predicted erosion. Shells had to be fired in numerical order to preserve the fit of the projectiles in the increasingly worn barrel.