The Chemistry of War
In the fall of 1914, the opposing armies on the western front huddled in their trenches near the Belgian town of Ypres, lobbing artillery shells at each other across a barren no-man's-land strewn with thickets of rusty barbed wire, craters, and splintered trees. Germany had launched the war in August by carrying out the Schlieffen Plan, a massive surprise attack through neutral Belgium that sought to achieve the rapid conquest of France in the west, followed by a knockout blow to Russia in the east before the United States decided to enter the war. The initial operations had gone according to plan, but when the kaiser's armies were thirty miles from Paris, a last-ditch counterattack by the French and British forces at the Battle of the Marne had halted the German offensive. Seeking cover from the lethal hail of shrapnel and machine-gun fire, both sides had dug in, building labyrinthine trenches that would ultimately extend some four hundred miles from the North Sea coast of Belgium to the Swiss border.
By fall, the adversaries found themselves trapped in a bloody stalemate in which neither side was able to advance. Infantry offensives inevitably bogged down after taking negligible amounts of territory, at a heavy cost in lives. Seeking to break the deadlock and regain the offensive, the Germans began to consider the use of toxic chemicals delivered by artillery shells to force the enemy out of his trenches. This idea was not entirely new: in 1862, during the American Civil War, a New York City schoolteacher named John W. Doughty had written to the Secretary of War suggesting the use of poison gas shells against the Confederate forces. He had designed a 10-inch projectile in which one compartment was filled with a few quarts of liquid chlorine and the second with explosives; when the shell burst, the explosion would convert the chlorine into an asphyxiating gas. But the Union's chief of ordnance, Brigadier General James Ripley, had been resistant to new ideas and had rejected Doughty's invention.
Because Germany possessed the world's most advanced chemical industry, it enjoyed an inherent advantage in this type of warfare. The main obstacles were the existence of an international treaty specifically banning the use of shells to deliver asphyxiating gases and the deeply held belief that toxic weapons were illegitimate. This "chemical weapons taboo" appears to have originated in the innate human aversion to poisonous substances, as well as revulsion at the duplicitous use of poison by the weak (including women) to defeat the strong without a fair physical fight. Efforts to outlaw the use of poisons in war dated back to the classical Greek and Roman period. During the Middle Ages, German artillery gunners pledged not to use poisoned weapons, which were judged "unworthy of a man of heart and a real soldier." The first known international agreement banning chemical warfare, a Franco-German treaty prohibiting the use of poisoned bullets, was drawn up in Strasbourg in 1675.
Before the second half of the nineteenth century, numerous poisonous chemicals had been discovered but could not be produced on a large scale. The emergence of the European chemical industry, which was capable of manufacturing vast quantities of dyestuffs and other synthetic chemicals, gave rise to new concerns over the potential use of lethal gases on the battlefield. In 1863, the U.S. War Department issued the Lieber Code of Conduct, which prohibited "the use of poison in any manner, be it to poison wells, or food, or arms." Similarly, the 1874 Brussels Declaration on the laws and customs of war, signed by fourteen European countries but never ratified, banned the use of poison, poisonous gases, and weapons that caused unnecessary suffering.
At the 1899 International Peace Conference in The Hague, representatives of twenty-six countries, including Germany, signed the first Hague Convention Respecting the Laws and Customs of War on Land. Article 23(a) of this treaty prohibited "poison or poisoned weapons," including the deliberate tainting of arms, bullets, food, or wells. The contracting states also signed a separate document, the Hague Declaration Concerning Asphyxiating Gases, which specifically outlawed "the use of projectiles, the sole object of which is the diffusion of asphyxiating or deleterious gases." This treaty effectively banned the use of chemical shells even before they had been developed.
In late 1914, however, amid the futile slaughter of trench warfare, the traditional legal and moral restraints on the use of poison gas began to erode under the pressure of military necessity. From the outset, the German High Command had interpreted the Hague gas projectile declaration as banning only the release of lethal gases from shells specifically designed for that purpose. The German military also considered tear gases and other nonlethal irritants to be equivalent to smoke and hence not covered by the legal ban. Indeed, the French had begun using tear gas grenades in August 1914, the first month of the war, albeit to little effect. Exploiting these loopholes, the Germans proceeded to develop a 105 mm artillery shell that was loaded with an irritant chemical (dianisidine chlorosulfate) and was also designed to generate shrapnel, so that its "sole" purpose was not the delivery of a toxic gas. In October 1914, the Germans fired three thousand irritant shells at the British forces near Neuve-Chapelle, but because the high-explosive charge burned the chemical agent and neutralized its effects, the British remained unaware that they had been subjected to chemical attack.
The Germans then developed a 150 mm howitzer shell containing seven pounds of another chemical irritant (xylyl bromide), once again combined with an explosive charge to disperse shrapnel. In January 1915, German troops fired more than 18,000 of these shells at the Russian positions near Bolimow, but the subfreezing temperatures prevented the liquid agent from vaporizing and rendered it harmless. The failure of these attacks with irritant gases, combined with a shortage of high explosives, led the German High Command to consider the use of shells containing lethal agents.
The individual responsible for developing chemical weapons for the German War Office was Professor Fritz Haber, a brilliant young chemist and ardent Prussian nationalist who directed the Kaiser Wilhelm Institute for Physical Chemistry in Berlin. Although born Jewish, Haber had converted to Christianity at the age of eighteen. In 1905, together with his colleague Carl Bosch, he had invented a revolutionary process for the large-scale synthesis of ammonia from atmospheric nitrogen. Because ammonia was used to manufacture nitric acid, a key ingredient of both fertilizers and explosives, the Haber-Bosch process freed Germany from its previous dependence on imports by sea of Chilean nitrates, which were cut off shortly after the world war began. Without a synthetic source of ammonia, Germany would have quickly run out of food and ammunition, and Haber's essential invention made him a national hero.
In late 1914, Haber had the idea of loading artillery shells with chlorine, which the German chemical industry produced in large quantities for the production of dyestuffs. When a shortage of artillery shells ruled out this method of delivery, he proposed instead that chlorine be released directly from pressurized gas cylinders, allowing the wind to carry the poisonous cloud over the enemy's trenches. This tactic offered a number of potential advantages: chlorine released directly from cylinders would blanket a far larger area than could be achieved with projectiles, and the gas would dissipate rapidly, allowing the affected areas to be occupied by friendly troops. Haber also noted that the release of chlorine from pressurized cylinders would not technically violate the Hague declaration, which banned only the use of specialized chemical shells.
In early January 1915, these arguments won over General Erich von Falkenhayn, the chief of the German General Staff, who considered poison gas "unchivalrous" but hoped that its use would result in a decisive military victory. As the site of the first chlorine attack, von Falkenhayn selected the Allied-held town of Ypres in Flanders, Belgium. Just west of the town, the line of Allied trenches extended about four miles into German-controlled territory, forming a bulge called the Ypres Salient that was nine miles across at its widest point. Holding the line on the left side of the Salient, near the village of Langemarck, were the French 87th Territorial Division and the 45th Algerian Division, made up of French-Algerian soldiers known as Zouaves. British and Canadian units defended the center and right portions of the bulge.
In mid-January, Haber ordered the chemist Otto Hahn and several other colleagues to help prepare the chlorine attack. When Hahn objected that chemical warfare would violate the Hague Convention, Haber replied that the French had already made use of gas-filled munitions and that countless human lives would be saved if the effective use of chemical weapons brought the war to a rapid end. The German chemists helped to organize a special unit for gas warfare called Pioneer Regiment 36. These troops received training and equipment for handling chlorine, including the so-called Dräger self-preserver (Drägersche Selbstretter), which they would don for their protection when releasing the lethal gas.
On January 25, 1915, General von Falkenhayn ordered Infantry General Berthold von Deimling, who commanded the German XV Army Corps at Ypres, to report to the field headquarters at Mezières. According to von Deimling's memoirs:
Falkenhayn revealed to us that a new weapon, poison gas, was to be used and that my corps area had been selected for the first attempt. The poison gas would be delivered in steel cylinders, which would be built into the trenches and opened when the winds were favorable. I must confess that the commission for poisoning the enemy, just as one poisons rats, struck me as it must any straightforward soldier: it was repulsive to me. If, however, the poison gas were to result in the fall of Ypres, we would win a victory that might decide the entire campaign. In view of this worthy goal, all personal reservations had to be silent. So onward, do what must be done! War is necessity and knows no exception.
Haber was dispatched to Flanders to organize and prepare the chemical attack. Under his direction, the German War Office shipped to the front 1,600 large and 4,130 small steel cylinders filled with pressurized liquid chlorine. On March 10, 1915, German troops from Pioneer Regiment 36 emplaced the cylinders along a four-mile line opposing the French trenches, burying them vertically in slit trenches to prevent them from being ruptured or destroyed by enemy artillery fire.
After emplacing the cylinders, the Germans waited for the wind direction to change. For more than three weeks, the prevailing winds at Ypres blew from west to east, which would have carried the poisonous cloud back over the German lines. Finally, in the late afternoon of Thursday, April 22, the wind shifted and began to blow from the northeast. The velocity was sufficient to carry the chlorine gas away from the point of release, yet slow enough for the cloud to linger over the opposing trenches before dispersing.
As the lowering sun bathed the Ypres Salient in a warm, golden light, the French and Algerian troops rested in their trenches, preparing the evening meal and enjoying the cool breeze that had sprung up. Around 5:00 p.m., the Germans began an artillery bombardment. The thump of heavy shell fire from 17-inch howitzers echoed from the northwest across no-man's-land, increasing rapidly in volume. Shell bursts flashed in the distance, spewing lethal fountains of dirt and shrapnel. Finally the bombardment stopped and it was dead still. Then over the German trenches rose a balloon on which three flares sputtered brightly.
At this signal, the German troops along the four-mile front simultaneously opened the cocks on the 5,730 buried cylinders. Pressurized streams of chlorine gas hissed from rubber hoses extending out of the German trenches and immediately turned white with the condensation of water vapor. A total of 168 metric tons of chlorine billowed out of the cylinders and merged into a vast, elongated cloud about five feet high. Heavier than air, the cloud drifted across no-man's-land toward the Allied trenches at a leisurely pace of about one mile per hour. Gradually the warmth of the ground caused the cloud to expand to a height of about thirty feet and assume a yellow-green color.
Sentries posted among the French and Algerian troops saw the strange cloud rising from the enemy trenches. Believing that the Germans were using smoke to mask an infantry assault, the French commanders ordered their men to mount the fire steps of their trenches and prepare to repel the enemy advance. But instead of the expected waves of German troops, the defenders saw only the roiling bank of yellow-green fog, moving inexorably forward. The usual explosions and cries of battle had been replaced with an eerie silence.
As the wall of yellow-green mist approached their lines, the French and Algerian troops smelled a pungent, acrid odor that tickled their throats, burned their eyes, and filled their mouths with a metallic taste. Moments later, the full density of the toxic cloud swept over them, veiling the world in greenish murk as if they had suddenly been plunged several feet underwater. Inside the cloud, the men could see no more than a few feet in front of them. The chlorine seared their eyes and burned the lining of their bronchial tubes, causing blindness, coughing, violent nausea, splitting headache, and a stabbing pain in the chest. Hundreds of soldiers collapsed in agony, their silver badges and buckles instantly tarnished greenish black by the corrosive gas.
On seeing the effects of the poisonous cloud on the forward trenches, the other French and Algerian units broke and ran in terror, dropping their weapons and equipment. Within an hour, two divisions numbering some ten thousand men had collapsed in disarray, tearing a gap four miles wide in the Allied line. Six miles away, the British troops of the Queen Victoria Rifles saw the yellow-green cloud in the distance and began to murmur in confused speculation. A soldier named Anthony Hossack later wrote in his diary:
Suddenly down the road from the Yser Canal came a galloping team of horses, the riders goading on their mounts in a frenzied way; then another and another, till the road became a seething mass with a pall of dust over all.
Plainly something terrible was happening. What was it? Officers, and Staff officers too, stood gazing at the scene, awestruck and dumbfounded; for in the northerly breeze there came a pungent nauseating smell that tickled the throat and made our eyes smart.
The horses and men were still pouring down the road, two or three men on a horse, I saw, while over the fields streamed mobs of infantry, the dusky warriors of French Africa; away went their rifles, equipment, even their tunics that they might run the faster.
One man came stumbling through our lines. An officer of ours held him up with leveled revolver, "What's the matter, you bloody lot of cowards?" says he. The Zouave was frothing at the mouth, his eyes started from their sockets, and he fell writhing at the officer's feet.
Excerpted from War of Nerves by Jonathan B. Tucker Copyright © 2006 by Jonathan Tucker. Excerpted by permission of Pantheon, a division of Random House, Inc. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.