Early in the morning of 24 October 1917, the newly constituted Austro-German 14th Army launched the Caporetto Offensive – known on the Austrian side as the Das Wunder von Karfeit or the Miracle of Caporetto. An integral part of the “miracle” was “Der Durchbruch bei Flitsch” – “The Breakthrough at Bovec”. In the two-pronged offensive, the use of gas shaped the deadly results in both zones of the attack.
Gas did not figure into the Isonzo Front as much as on the Western Front. Uncertain wind conditions, topography and climate made such attacks carried out by the Austrians a chancy operation. Many times, the gas would come back onto the attackers instead of the other way around. In the cold mountains, gas did not normally serve as an effective means of attack.
On the Western Front, gas accounted for about 25,000 deaths. On the Italian Front, gas still claimed about 7,000 lives, many of those in two operations (By contrast, it is estimated at least 60,000 lives were lost from avalanches, most in the Dolomites to the west, but ten thousand in the Julian and Carnic ranges to the east.).
CHEMICAL GAS ON THE BATTLEFIELD OF THE GREAT WAR
Forms of gas used against enemies predated World War 1. “The use of projectiles the sole object of which is the diffusion of asphyxiating or deleterious gases” became one of the methods of war prohibited by the 1899 Hague Convention. That treaty had been signed by Germany, Britain, France and Russia. Regardless of the treaty, Germans and French were quick to dump tear gas upon their enemy as early as 1914. Many of the first attacks were relatively harmless. One attack on the Eastern Front against Russian troops at Bolymov in Poland saw tear gas shells failing to volatize and disperse because of the frigid conditions encountered in the attack of 31 January 1915.
TEAR GAS LEADS TO STRONGER MEASURES
While tear gas did not seem to have a future in the war, German scientists were hard at work on other chemicals. As important as the gases was the means with which to introduce the gases onto the battlefield. Chemist Fritz Haber – winner of the Nobel Prize in Chemistry in 1918 – suggested mortars as a more effective way to bring gas onto the battlefield than explosive artillery shells. He also suggested gas discharged from cylinders could form a cloud. The problem was the gas cylinders required excavations which the enemy could notice. Artillery fire could then destroy the cylinders leaking the gas into the wrong trenches.
Germany moved from tear gas – non-asphyxiating – to chlorine – definitely, an asphyxiant. By not using artillery shells for delivery but through release from the gas cylinders, the gas clouds were not a direct violation of the Hague Convention. The chlorine gases first came into use on the Western Front during the Second Battle of Ypres in an attack 22 April 1915. After the initial use, the Germans gained a breakthrough with their new weapon. However, they failed to fully exploit the surprise weapon and their attack was halted. Very quickly, anti-gas measures would quickly negate the use of gas. Even so, the gas genie let out of the bottle would not go away as both sides used gases in one form or another for the rest of the war.
GAS CYLINDERS AND GAS SHELLS
Gas clouds could only affect front line trenches before dissipating. Leaking cylinders were prone to counter artillery fire which could then destroy the cylinders. Chemical shells were improved upon for artillery delivery of the different poisons used by the various armies. Gas shells could land with a plop that defenders might dismiss as a dud. The gases could then go to work before the soldiers took measures to counter the aerial poisons. Shells could also be used to spread the gases to rear areas. The main flaw was the small payload of gas included in a shell. Many gases needed to form a cloud to be effective killers. Mustard gas was one gas effective without forming a cloud. It was an ideal gas for the artillery delivery.
GAS MORTARS
Both sides developed gas mortars by 1917. The British used the Livens projector, an 8-inch diameter tube dug into the ground at an angle. A propellant would fire a gas cylinder of 30-40 pounds of gas out to a range of 1,900 meters. A grouping of such mortars would then saturate an area similar to the earlier gas cylinders, but at distances not achievable by the earlier cylinder releases. First used at Arras 4 April 1917, the British would mass 3,728 cylinders for an attack a year later -31 March 1918 – at Lens.
GAS ON THE ISONZO FRONT
Austria-Hungary had chemical capability, but the Emperor Franz Jozef saw it as a coward’s weapon. The first usage by the Empire did not occur until an attack on Monte San Michele in the lower Isonzo 29 June 1916. Italian defenders were taken by surprise by the chlorine gas attack and the first two Italian lines were captured. Subsequent counterattacks regained a status quo for the Italians.
Gas would not play a significant role along the Isonzo until the Twelfth Isonzo. Italian gas masks were simple filter affairs, effective against chlorine, but so were wet rags. Phosgene had developed as a chemical six times more potent than chlorine. Used first by the Germans, phosgene became chemical of choice for the Allies. A few months later, diphosgene was developed – phosgene plus chloroform. Diphosgene was able to destroy chemical filters then attacking the lungs. Estimates put 85% of chemical deaths on the doorstep of either phosgene or diphosgene. Not only could diphosgene overcome simple gas mask designs, but the gas was also harder to detect by defenders on the ground.
TWELTH ISONZO – BREAKTHROUGH AT PLEZZO
In response to the slow attrition grinding away at Austria-Hungary’s ability to defend along the Isonzo Front after eleven Italian offensives, German command decided to help their ally, at last. 1917 saw the Russian Empire collapse with the resultant government no more successful at fighting the war. By the autumn, the country was well on its way out of the war freeing up units of both Germany and Austria-Hungary.
Hindenburg, over Ludendorff’s objections, agreed to send German troops to the Isonzo to help push the Italians back from their recent gains in the tenth and eleventh offensives. He had a couple of requirements before sending German troops: one was to put the offensive force, the newly created 14th Army under German command; another was that German troops would only be available until December at which time they would return to the Western Front where they would ready for the 1918 Spring Offensives. So, seven German Divisions plus ten Austro-Hungarian divisions became part of the new army commanded by German general Otto von Below.
CHEMICAL PREPARATION
Another chemist serving with Haber was Otto Hahn. Like Haber, Hahn would win a Nobel Prize in chemistry in 1944 for work he helped on regarding the discovery of nuclear fission. Hahn spent a lot of his time during the war scouting for positions along the various fronts for gas attacks. Disguised in Austrian uniforms, he and two other officers selected such a site near the town of Bovec – Flitsch in German and Plezzo in Italian.
To deliver the chemicals, rifled minenwerfers, similar to the British Livens projectors, were selected. In the days just before the 24 October attack, 912 gas mortars were dug about 130 meters behind Austrian lines just south of the positions on the little hill of Ravelnik by a special engineering company specializing in gas warfare – 35th Pioneer Battalion.
The target selected was a small valley just to the west leading down to the Isonzo River from the plains around Bovec. Both the gorge and the entrances were targeted, only reachable by high trajectory weapons like a mortar. All of the mortars were wire together so they could be fire together electrically. Just after 2 am on the 24th, following an artillery gas bombardment, the mortars went off.
GAS ATTACK
Gas attacks launched from mortars required close range and concentration into a small area. Weather had to be correct for such an attack to be successful in order to keep the gas concentrated enough to do its damage. Firing at night meant the winds were light with fog in the area. Rain developing later in the day after the gas attack. That would have diluted the results.
From the 912 mortars dug, 894 were ready for firing. 818 gas canisters were firing off into the gorge delivering 6.5 tons of diphosgene and dichoro-arsenic gas. Another 29 mortar barrels burst affecting seven of the men from the Pioneer unit while another two men got enough exposure, they later died. Of the 47 failed charges, they were refired a half an hour later. The pioneers then tried to reload the mortars with explosive charges, but due to barrel bursts, only 269 fired again between 0630 and 0830.
The Austrians launched an infantry attack at 0900 to the north of the gassed area. Storm troopers, men of the 22nd Austrian Schützen (Rifle) division, attacked the Italian positions at 9 am. Seven hours after the gas attack, the air was free. Only a few Italians still lived and those seriously injured from exposure. The gas settled into the little canyon creeping into all of the little dugouts where many of the soldiers had been sleeping. The gas killed most of the 600-800 men of the 87th Regiment of the Brigata Friuli. Very few men were able to put their masks on before dying. Italian masks were ineffective against the gases used, but no masks on either side could help when enough gas was concentrated onto a small area. Even with a mask on, there would not have been enough air to breathe.
The collapse of the Italian front line and failure to establish a defensive depth posture led to an open door through which the Austrians punched. The entire Bovec basin soon fell with the pass to the west – Passo Tanamea – captured. That opened a passage to the Friulian Plains of northeastern Italy beyond. Here is maybe the best map of the immediate days of the campaign.
LANDSCAPE TODAY
The mortars were dug in just to the south of the road leading from Bovec to the camping areas of Vodenca along the confluence of the Koritnica and Isonzo. The targeted gorge was a bivouac area for the Italians defending the first two front lines. A road leads down through the little valley to cross the Isonzo on a bridge across to Čezsoča. Near where the road begins its descent, a small monument inside a little cavern can be found to the Italian defenders who died that morning. Other monuments to the defenders have been moved to the east side of the Italian ossuary at Kobarid-Caporetto.
After the war, the entire Bovec basin would be given to Italy. That land exchange lasted until the end of the next war.
POSTWAR AIRFIELD
GAS CHEMIST POSTSCRIPT
Fritz Haber went on to invent Zyklon A, an insecticide used to fumigate grain. Awarded the Nobel Prize in 1918 for work on synthesizing ammonia from nitrogen and hydrogen – an important part in the development of large-scale fertilizers for food production. Hahn was Jewish by birth though he had converted to Christianity. He would die before the next war when it was used on a wide scale to murder millions of Jews in the extermination camps – many from his extended families. Haber and his immediate family fled Germany in 1933. He died shortly afterwards.
Otto Hahn worked with the Nazi atomic programs and after the war was a frontline critic of nuclear armaments. He was a critic later on of the Nazis and their racial programs, but early on Hahn was seduced by Hitler and his movement. In an interview with the Toronto Star in 1933 when he a was a visiting professor at Cornell University, Hahn noted: “I am not a Nazi. But Hitler is the hope, the powerful hope, of German youth… At least 20 million people revere him. He began as a nobody, and you see what he has become in ten years.… In any case for the youth, for the nation of the future, Hitler is a hero, a Führer, a saint… In his daily life he is almost a saint. No alcohol, not even tobacco, no meat, no women. In a word: Hitler is an unequivocal Christ.”
Frightening to read about the use of gas warfare in WW1.
Frightening what it led to in the years beyond, too, even with the Nobel Prize.