A map of Paris showing the fall of projectiles and casualties: killing 256 (corrected figure) and wounding 620.
The forest of Crepy-Fourdrain concealed sinister secrets. Deep inside the primeval woods was a naked concrete command post next to a man-made clearing. Its stark, cold walls, dripping with dew from an early morning fog, contrasted garishly with the greenery and chirping of springtime. Uniformed men entered and walked to a map table, then peered outside at their colossal charge. Clinking and clanking as it cranked to higher degrees of elevation, a monstrous metallic tube seemed to rise out of the misty forest floor. Over 100 feet long and weighing 200 tons, the creature waited for sustenance. Cranes hoisted a brass-tipped projectile! “Toi, toi, toi—do your job, Jeanette!” said one artilleryman affectionately, as the shell disappeared into one end.
Inside the bunker a phone rang. It was the OHL, ordering the giant gun to fire on Paris, 128 kilometers to the southwest. The order to shoot passed down the line. Thirty heavy artillery batteries stood ready to fire their guns simultaneously to provide a camouflage of sorts to prevent immediate counter-battery fire. At 7:09 a.m. on 23 March 1918, the salvo went skyward with a roar. One shell left the others far below, rocketing into the icy stratosphere at 2 kilometers per second. After 21/2 minutes it reappeared in the skies high above Paris. Thirty seconds later it plummeted into the City of Light.
The gargantuan “Paris gun” shot 320 shells at the French capital that spring and summer, most exploding in the inner city. Its mission was to break enemy morale as German shock divisions broke through allied lines and drove on Paris. The very existence of this hideous, high-tech cannon was a cruel mockery of the outmoded military world that had practiced its prescriptions for victory on the plains of Konitz 37 years earlier. But it was also a sign and symbol of the German Army’s rapid adjustment to the brave new world spawned by Plevna, as well as by the Great War. Would it be enough?
Germany had some success with ultra-long-range artillery during World War I, notably with the so-called ‘Paris Gun’. The Imperial German Navy, which constructed and manned them, called them the ‘Kaiser Wilhelm Geschütz’, and they were used sporadically from March to July 1918 during the massive and so nearly effective German counter-attack in Picardy to bombard the French capital from the region north of Soissons over 100km (60 miles) away. They were 38cm (15in) naval guns, as mounted aboard the battleships of the day, sleeved down to 21cm (8.25in) with liners whose rifling consisted of deep grooves within which lugs on the shell located, a method first adopted in the early days of the development of the rifled gun in the 1840s. This same method was to be employed in the very long-range artillery pieces developed in Germany for use in World War II – the K5 battlefield weapons and the ‘strategic’ K12, built to fire on England from the French coast – though the shells of these guns were rather more sophisticated. Heavily over-charged, they projected their shell into the stratosphere where, meeting little air resistance, it could extend its trajectory considerably. The use of a far heavier charge than the gun had ever been designed to employ soon caused the barrel to wear out – it seems that 25cm (10in) of rifling was destroyed with every round fired, and that a barrel’s life was just 50 rounds in consequence – and it then had to be rebored or relined. The Paris Guns, with three mountings and seven barrels, which were employed serially, fired just 303 rounds towards Paris, slightly more than half of which (183) actually landed within its boundaries, killing 256 and wounding 620. These results made the entire project highly cost-ineffective, except in propaganda terms. Though these first-generation ultra-long-range guns were to enjoy only limited success, they did, albeit imperfectly, solve the problem of how to bombard high-value area targets with relative impunity from outside the range of counter-battery fire. In more modern times they would be sickeningly vulnerable to air attack, since they presented big targets, were hard to conceal, and impossible to move at very short notice, but in 1918, despite a huge campaign to locate them, they were never found. By the time the Allies overran the Forest of Crepy, where they were located, there was no sign of them left save their concrete emplacements. Another problem – and many said a more pressing one – remained: how to subdue organised defensive positions like the modern fortresses of the Maginot Line, which ran down the French-German border, in the shortest possible time. For this, a task which was to be undertaken at shorter range, an approach which can almost be characterised as ‘brute force and ignorance’ was all that was necessary, and the guns in question were no more than straightforward developments of the siege guns which were some of the first weapons deployed in 1914.
To the south-east, seventy-five miles away, lay the great city of Paris; beginning its busiest weekday, the people irritated over another raid alarm during the night, but still feeling secure with the French lines intact from La Fere around the Laon Corner and east past Soissons and Rheims.
The gunnery officer, with his expert technicians, made a careful and final minute examination of the great gun. 50 many times they had done this, but one can never quite satisfy himself that so valuable a weapon is in perfect condition. The test powder case entered perfectly; the firing mechanism worked perfectly; the elevating and traversing mechanisms were in perfect order; the azimuth and elevation instruments, delicate affairs and easily injured, were taken from their cases and fitted to the carriage and to the socket connected with one of the cradle trunnions.
The orientation and ballistic officers were busy checking their calculations of the firing data. It would be horribly embarrassing if the first shot were to miss Paris through a blunder in the calculations. It was frosty, and the powder was a degree under temperature; so a 50.5-kilogram forward charge was ordered. Cold powder does not build up to pressure . so rapidly, so a slight extra charge was necessary. The middle and base charges weighing 75 and 70 kilograms were fixed, already made up. The forward charge was quickly weighed out, bagged, and ready. All were kept in the storehouse until needed, to keep the temperature at the proper point.
It was rapidly approaching seven o’clock. The weather forecasters thought the fog would hold for a part of the day, but one must not take unnecessary chances on being seen. The discharge of the gun and other guns in the corner would be heard over the line only seven miles off, and ‘planes would be up all too soon. The commanding officer therefore ordered the smoke-pots to the north lighted so that there would be a good screen over the whole corner in an hour. The gunnery officer called up the batteries north and south to inquire if they were ready; they were, and were standing by for his signal. Those guns would set all French sound-ranging instruments jiggling so violently that the discharge of the great gun would be undecipherable on their record charts.
The order for loading was given, and all sprang to with a will. The projectile was hauled over on the ammunition track, hoisted to the loading platform, and its tray locked to the massive gun-breech. The crew that had done this in practice so often fitted the rammer carefully to the base, slid the projectile forward to the end of the powder-chamber, carefully turned it to fit into the grooves in the gun, and then, with a mighty heave, rammed it home. The powder- charges were already coming up to the loading platform; the first was slid into the powder-chamber, then the second; each was pushed forward into place with the rammer. Then two tiny pressure gauges were fitted into special sockets in the wall of the chamber, and the brass-cased base-charge was put in. The gunnery officer with his sergeant inspected every move critically; the order to close the breech was given, and, with the turning of the crank, the huge block of steel moved across, sealing in the projectile and powder. The block was locked in place, and the crew scrambled down from the platform. The sergeant inspected and set the firing mechanism and signalled” All’s ready” to his officer. At once the switch was closed, and, with the hum of the elevating motor the great gun began to rise to its firing position.
What an impressive, awe-inspiring sight! The massive carriage, twenty-five feet high, and a gun whose length equalled the height of the average ten-story building slowly raising its muzzle far above the tree-tops. All of this in a clearing in a wood, early on a foggy morning, with a death- dealing instrument to be sent to far-off Paris in a few minutes. How could one describe the emotions? Were they those that would be experienced as the switch is about to be closed in a death-chamber for an execution; or as a great battleship is ordered into action? Perhaps both.
The gun was up; everyone was out of the way who had no special function. The elevation was carefully set, checked by a special quadrant and by a second gunner. All was ready. The gunnery officer had all batteries on the ‘phone, and when he received the final signal that the elevation had been checked he called to all to stand by for the order. At exactly 7. 17am he gave the order on the ‘phone; instantly heavy guns, north, south, and west, fired practically in unison; in a second the order -to the Paris Gun sergeant. With a terrific, crashing roar the great gun belched forth a huge cloud of orange-red smoke and incandescent gas. The projectile had gone. The great gun recoiled violently in its cradle, came to rest, and then slowly slid forward into battery.
At once the elevating motor was set going, and the gun slowly descended to be inspected and loaded again as before. Meanwhile the seconds ticked off as the projectile mounted to unknown heights in its Bight toward its target. From a position of rest in the gun it had been set into motion with violent twisting and pushing. A million pounds pressure had been exerted on its base while it travelled up the gun. There had been a terrific straining to set it turning at the rate of a hundred revolutions per second before it left the gun so that it would remain head on throughout its journey. In a fiftieth of a second it left the muzzle of the gun at a velocity of 5260 feet per second, a mile per second, and with the energy of 8,000,000,000 foot-pounds. As the projectile emerged into the air it encountered a pressure of two thousand pounds from the force attempting to stop it. In twenty-five seconds it was twelve miles high and in air only one-tenth as dense as that at the surface of the earth. It had lost heavily in velocity getting through that layer of dense air; from 5260 to 3000 feet per second. And the temperature had dropped below anything experienced on earth, at least to 70 degrees below zero. In ninety seconds it was at its maximum height, twenty-four miles, and turning over. There was no air to speak of up there. For at least fifty miles of its range it travelled in a virtual vacuum. The velocity at the top of its path had dropped to 2250 feet per second. And then it began its downward journey. It gained steadily in velocity, until at the twelve-mile level it had regained the 3000 foot- seconds it had before. But there began the real resistance to its flight; its velocity increased slightly, 75 foot-seconds, and then it began to slow up even while falling.
At the gun officers were studying their watches; 150 seconds; 160; 170; in just a few seconds, at the 176th, at some place in Paris that projectile would strike and burst. With what effect? Not for forty-eight years had the great city of Paris been shelled. Not since 1870, when the besieging German Army fired more than a million solid shot, some hot, and spherical shell into the city. In a few seconds it would again be a city bombarded by German guns. Perhaps in that great city from which the projectile was now only ten seconds, eight seconds, distant, certain people were walking toward a corner, to walk into the projectile or out of danger. One hundred and seventy-six seconds; 7.20. The projectile had burst.
Before the cloud of smoke from the discharge had floated away over the trees the elevating motor was bringing the gun slowly down to its loading position. Two of the crew at the breech crank slid the great block slowly to the side. As was expected, the brass case of the base-charge had been almost melted away; the base was thick and heavy, and most of that remained. But it would not be possible to use these cases again, as with the ordinary gun. As soon as the case was removed there was a rush of air through the bore that swept out the remaining gases. The bore was hastily inspected, the pressure gauges removed and tossed down to the waiting ballistic officer, and, after swabbing out the powder-chamber, the crew at once entered, placed, and rammed the next shell. As soon as it had been rammed they measured the distance from its base to the breech face of the gun with a special gauge provided for that purpose. This was a part of the procedure in calculating the weight of the next charge of powder. No addition would be made to the charge of powder for the first four and a half inches of advance of the point of stopping of the shell. But as soon as the advance equalled 4.5 inches the powder-charge would be increased by 2.2 pounds. Then when the advance had progressed 100 millimetres, or 3.94 inches, further, and for each hundred millimetres thereafter an additional kilogram of powder would be added. So the measuring of the point of stopping of each shell would be an invariable part of the procedure in loading and calculating the powder-charge.
Again was the gun unique. In no previous gun had such instruments as pressure gauges been employed to learn the probable point in range at which the projectile struck and to correct the calculated weight of the powder for the next charge. The gauges were quickly opened, and the tiny cylindrical pellets of copper removed and measured with a micrometer gauge. Those pellets had been cut from bars of copper which had been compressed under a definite pressure. The pellets had been machined carefully to the diameter and length which they had before the gun was fired. When the gun was fired the terrific pressure of the gases in the gun passing through a tiny hole in the end of the gauge, a hollow cylinder of steel, forced a piston within down on the copper, crushing it slightly. The new and reduced lengths of the copper pellets then indicated the maximum pressure of the gases in the gun for that shot. From the range-table it should have been 59,000 pounds per square inch for the corrected range of 67. 1 miles. But the gauges said that the pressure had been only 53,800 pounds. This was perhaps to be expected; a cold gun. Seven and a half pounds extra powder were quickly added to the variable powder-charge, and the bag sewn up for loading. The crew then fell to with enthusiasm to finish loading the second charge.
Meanwhile the ballistic officer continued his calculations to learn where the first shot had probably fallen. He found that it had probably burst at a distance of seventy and a quarter miles from the gun. This was plotted on the map and found to be up in the north-east section of Paris proper, probably in the region of the Boulevard de la Chapelle or Quai de Seine, provided, of course, that it had not deviated far to the right or left. Not at all bad for the first shot from a cold gun. Perhaps the extra powder would land the second closer to the centre of the city. It was not probable that there had been much deviation to the right or left, for there would be but little drift to these projectiles. Since the rifling of the gun had a right-hand twist, the projectile rotated in a clockwise direction, considering it from the rear; but the atmosphere through which most of its 92-mile path passed was so rare that there could be but little of the usual drift or deviation to the right for a right- hand rotation.
The unique device, the pressure gauge, which revealed to the gun crew approximately where each shot had fallen almost as soon as it had struck, was a fair substitute for the air observer’s reports in its effect on morale. It was an indispensable accessory in conducting the fire of so unique and valuable a weapon. As the crew scrambled down from the platform after loading the second round they examined the map eagerly and with enthusiasm over the result.