The War of the Engineers I

The French engineers who designed the forts were well aware that the rifled, breech-loading guns that were increasingly coming into use in the 1870s were far superior to the cannon that Vauban and his followers had in mind when they designed and built their forts. The difficulty men like Séré de Rivières faced was unprecedented, however. In the decades between 1871 and 1914, there were three successive revolutions in gunnery.

These dramatic and sweeping changes transformed the nature of warfare in a fundamental way. This shift can be seen quite clearly, because, starting with the wars of the 1860s and 1870s, the medical services of many of the combatants began to keep records of their woundeds’ cases. As most of us would expect, the vast majority of wounds were caused by standard infantry weapons: rifles and sidearms. The only surprise revealed by these reports is the extremely low incidence of wounds caused by edged weapons—bayonets, knives, and swords. As the American summary of the Civil War data points out, there was very little hand-to-hand combat: “The bayonet and saber were military weapons of little significance,” is how the United States surgeon general put it. The contrary idea is a myth. But then, as Jean-North Cru pretty much established, a great many battlefield accounts are fictional.

The point is germane, suggests a certain healthy skepticism about stories of intense hand-to-hand fighting in the trenches. That is particularly the case given the dramatic shift in the causes of wounds that occurred in the First World War. Abruptly, the vast majority of wounds now came from artillery shells of various kinds. And this was true despite all the attention given to the power of the machine gun. In studying the data recorded by the medical services of the combatants, one comes to the conclusion that very few soldiers fell victim to rifle fire.

Another way of looking at what happened is to see it as a paradigm shift, as indeed it was. The successive revolutions in artillery transformed the nature of warfare. Some armies adapted to it much more quickly than others, which is why they were more successful in combat. As with armies, so with their chroniclers: A good many military historians continued to write about this war as though it were of a piece with the wars of Napoleon, with the Crimea, or South Africa. Nor is it fair to blame them. Stories of marksmanship and man-to-man combat are inherently more satisfying than Bernier’s image of human bodies being transformed into a ghastly confiture.

Moreover, just as gunners and engineers were always better educated than their counterparts in the cavalry and infantry, understanding their concerns, like mastering understanding their craft, requires delving into technical areas. But without a certain understanding of those areas, it is basically impossible to understand grasp both the battlefield successes of the Germans during the war, and the complicated sequence of events that led to the battles for Verdun. Besides, the story of these revolutions is intrinsically interesting.

THE FIRST TRANSFORMATION

As Séré de Rivières and his colleagues at the defense committee worked out their plans in the 1870s, they were well aware of how recent developments in the weaponry available both to the infantry and the artillery had impacted the battlefield. But to their way of thinking, the most recent advances would work to the advantages of the forts, with their prepositioned heavy artillery, safely shielded from view.

Up until the 1860s, or about the time of the American Civil War, the standard infantry weapon was a smoothbore musket. Although sturdy and durable, these weapons were highly inaccurate, and with a very short range. Forty meters was about the optimal, and even then the chances were pretty good that musket fire would miss.

In consequence, gunners who were one or two hundred meters back were basically invulnerable, could fire directly at their targets. So rifling, the practice of grooving the insides of the barrel of the gun tube, was a rude shock. A projectile fired from a rifled gun tube was vastly more accurate, and over a much longer range, particularly if it was a breech– as opposed to a muzzle-loading weapon.

Muzzle-loaded rifled muskets had been around for more than a century. But soldiers using rifles (as opposed to smoothbores) were specialists. Their weapons were finicky and fragile, and reloading them was a laborious process. The rifled weapon only became truly practicable on the battlefield when the technology improved to the point that a breech-loading weapon firing a metallic cartridge became cheap and reliable. By the mid-1860s, both the French and the Germans were equipping infantry with such rifles. These early weapons were a far cry from the rifles of 1914, but they were also a long way from the muskets of 1815.

Suddenly gunners realized that their traditional positions during battle turned them into so many targets. A volley of decently aimed rifle fire from a platoon of ordinary infantry could wipe out a whole battery of gunners, so the sensible response was to move out of range.

But that led to a problem: the gunners could no longer see their targets. So artillery fire became a much more complicated affair. The gunners needed observers to watch the fall of the shells and relay back corrections. This relatively new idea of not being able to see your target was called indirect fire.

Now it seemed to the committee, logically enough, that when it came to indirect fire, fortifications would give the defenders a great advantage. The observers were protected by the forts, would be looking out of small observation slits, or be in armored cupolas. The guns would mostly be well behind, but the beauty of the idea was that since both observers and guns were fixed in place, it would be an easy matter to dial in the exact location where you wanted to land your shells.

By contrast, the attackers would have to get into position to figure out what to do, and all the while they’d be under fire from the defense. Trying to attack a fort would be tantamount to suicide.

Producing infantry rifles was a much simpler process than producing rifled artillery, because the forces expended when the projectile was fired were so much less. Of course, the breech-loaded projectile fit much more snugly than the old muzzle-loaded one, so in consequence the forces generated were much greater, as there was hardly any leakage. But still, in order to make this principle workable for the ordinary soldier, the bullets themselves became lighter, even as their velocity increased.

Now the difficulty for artillery designers lay in scaling up the weapons. The forces required to propel a 75-millimeter-diameter shell were not simply ten times greater than what was required to propel a 7.6-millimeter shell, because the artillery shell weighed numerous multiples more than the bullet. And this was made all the more difficult if the gun was a breech-loader, since all rearward force was directed against this end of the barrel, which, in order to operate properly, had to have a mechanism that allowed it to open and close—otherwise the shell couldn’t be loaded into the rear.

But by the mid-1870s, about the time that fort building was well launched all over France (and Germany and Belgium and Austria and Russia), European gun designers began to close in on the problem. In Germany and Austria, this was done by private firms working on their own: Krupp and Skoda. In France the situation was slightly more complex, with individuals working for both government and private arsenals.

The key breakthrough for the French was made by a military officer, Charles Ragon de Bange, who figured out how to design a breech mechanism that would handle the forces involved. By 1878 his guns were in production, and in recognition of his abilities, French gunners referred to almost all the guns designed during this period by his name, even though some were actually designed by someone else. But De Bange became the generic designation for all French artillery designed right up until 1897.

Thus far—by, say, 1881—the engineers weren’t worried, because although the De Bange guns had more hitting power and longer range, they had factored all that into their designs. Even a direct hit from one of the new De Bange guns wouldn’t do any serious damage to their forts.

That was because there was a trade-off involved with these new guns. Since the expanding gases were so much more powerful, the gun tube and its mount had to be considerably sturdier. And although advances in metallurgy meant that immensely stronger metal could be employed, a certain mass was still necessary, and that mass meant weight.

Practically speaking, then, if an artillery piece was going to be mobile, able to accompany troops in the field, its weight was restricted to what could be pulled by a team of six horses. That worked out to a sort of constant; that is to say, everybody’s standard field gun turned out to be a weapon that fired a shell of around 80 millimeters over a relatively flat trajectory, with a usable range of about 6,000 meters at most. The shells fired by these guns could do horrible damage to infantry, but their explosive payload was too feeble to do anything much against fortifications, and indeed gunners mostly carried only shrapnel shells—effective only against masses of troops in the open.

Heavier weapons were thus not simply those firing larger (heavier) shells, but guns that weighed considerably more. To the extent that the armies all divided their artillery into two categories: field artillery, described above, and siege artillery. The latter was not really designed to be transported into the field and sent into action immediately. So the fort builders, eyeing their hundreds of batteries of heavy weapons, already in place, their magazines securely protected, naturally felt that the advantages were all on their side. The guns directed by the forts could destroy any enemy artillery before they could even get set up to fire.

Besides, there was no need for the fort to be invulnerable. It had to do its duty for only a week to ten days, by which time the armies would have been deployed, the battle joined.

THE GUNNERS STRIKE BACK

Unfortunately for the engineers, their great project was only just winding down when they received some truly frightening news. Between 11 August and 25 October 1886, French gunners conducted a series of experiments on the fort of Malmaison, outside of Laon. Malmaison was a 36,000-square-meter rectangle, and had been selected because of its relatively exposed position. While a delegation of delighted gunners and apprehensive engineers watched, the fort was bombarded.

The gunners fired 167 155-millimeter shells and 75 shells from 220-millimeter mortars, all system De Bange guns dating from 1878.

The results were very bad news for the engineers. To their consternation, the shells, particularly those from the mortars, smashed in the carapace of the fort, pretty much destroying it completely.

The guns hadn’t changed, but the explosives used in the shells had. The new explosive was substantially more powerful than what everyone had been using before. The forts had been designed to withstand the older version, but the new shells were devastating.

Now, by the 1870s, everyone involved understood the chemistry of high explosives. There was a whole family of trinitrates, including trinitrophenol (TNP) and trinitrotoluene (TNT), and any competent chemist could make them in a school chemistry lab—provided he had the raw materials. Assuming he didn’t blow himself to glory, since TNT in its pure state is an extremely volatile compound, and TNP is even worse—or better, in terms of explosive energy.

The difficulty is that the trinitrates are extremely volatile: any sort of shock will set them off, such as heat or vibration. Firing an artillery shell involves both of these factors, so the difficulty was figuring out how to adulterate the explosives so they could be used in shells. In modern parlance, this is called weaponizing, and by the mid-1880s the French succeeded in weaponizing trinitrophenol, which they called melinite, in a rather feeble attempt to disguise what it actually was.

A kilogram of this new material contained three or four times as much energy as what gunners had been using. So much so that the new melinite shells were promptly dubbed les obus torpilles, or torpedo shells, since, compared to the older shells, the new ones were more like naval torpedoes.

De Bange was no fool: His weapons, particularly the 120 – and 155-millimeter guns, were massively overbuilt, could easily fire the new shells. Prudently, the defense committee realized that the Germans probably weren’t far behind, and that in consequence everything built before 1885—which was basically everything—was now obsolete.

For the engineers who had been beavering away with fortifications, the system of De Bange weapons firing melinite shells was a horrifying development. As they saw with the Malmaison, the new shells were capable of destroying the masonry of their forts. Gloomily, they reckoned that everyone else would soon be filling their shells with some version of melinite, and they were right. Within a few years all the major powers were using some local variant of one of the trinitrates. The Germans, prudently, went for weaponized trinitrotoluene, which was less nasty to handle, but the end result was pretty much the same.

The 220-millimeter mortar shell was a particularly obnoxious development. Historically, siege artillery aimed to blow holes in the walls of a fort or castle. There were several practical reasons why gunners confined themselves to that function, the most significant being that, generally speaking, fortifications tended to be on higher ground, so the besiegers had to contend with steep angles of fire if they were going to get a shell over the wall. Before the advent of melinite, the actual explosive force of a typical shell was such that there wasn’t much damage to be done by one that simply flew over the walls and landed . . . somewhere.

Mortars were guns with very short barrels, capable of near-vertical fire over short ranges (one being a function of the other). They had been around for a long time, but, aside from naval uses, they weren’t very effective, precisely for that reason: the shells didn’t have enough explosive force to be worth the difficulties of aiming and firing, and, of course, gunners preferred to be able to see their targets.

But a 220-millimeter melinite shell was a different matter entirely. The relatively short range of the mortar meant less stress, because less explosive was needed to force it out of the barrel. Since the shell was less stressed, it could have a higher explosive payload. Drop one of these shells onto the roof of some part of the fort, and it would do enormous damage.

What made the situation truly distressing was that both of these new guns were, comparatively speaking, portable. Not in the sense that the standard field guns used by all the major powers were, but the weight and size of the shorter version of the 155-millimeter gun meant that it could be pulled along the same roads as its smaller brethren, albeit at slower speeds and with more effort. But it was light enough that you could mount it on a regular wheeled gun carriage, which meant that it could be pulled up and brought into action just like a field gun.

Now, the engineers had never claimed their fortifications were invulnerable, only that they could withstand the artillery that an army was likely to bring up during its advance. By the time it got its siege guns into place, mobilization and deployment would have been completed, and the traditional battles would begin.

So the Malmaison demonstration was the complete reversal of the basic suppositions that had led to the forts. The keystone of the national defense policy that Séré de Rivières had lobbied for was now dangerously obsolete.

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