Austrain-Hungarian guards circa 1916

WW1: Civil engineering achievements at the Great War's Southern Front

The least-known First World War theatre in the Dolomites was the area of bloody battles over freezing precipices which called for some extreme civil engineering.

The least known of the First World War theatres, the Southern Front in the Dolomites was resplendent with drama and tragedy. Most of all, it was a challenge for military engineers forced to work under extreme conditions. Its Front Line ran almost entirely through the mountainous, difficult terrain along the border of the Kingdom of Italy with the Austria-Hungary Empire. The beauty of the Dolomites contrasted sharply with the hurdles this kind of terrain presented to soldiers: the stand-alone, ragged massifs created a micro-geography where an enemy position just a few metres away could be hidden from view. This high-altitude war called engineers - a profession rarely basking in the limelight of military history - to the forefront.

The fort belt

The most visible contribution of civil engineering to the war effort is probably the string of fortresses built well before the conflict by both Austria and Italy. The “fort belt” was at the time probably the most advanced in the world - a real breakthrough in the fields of construction, armour and metalworking.

Technological innovation in weaponry, particularly introduction of high-explosive grenades with shrapnel instead of black powder projectiles, rendered masonry and earth fortresses obsolete. Early 20th Century forts, built mainly of reinforced concrete, were advantageous for defence: the war was, above all else, a tragic conflict of attrition.

The idea, developed by Belgian General Brialmont, called for a string of heavily armoured big fortresses, with the artillery well protected inside. His concept was ideally suited to the rugged terrain of the Italian front. Of the two opponents and future enemies, Austria-Hungary had a better developed economy, more resources and a well-functioning engineering corps. The Austrian forts along the southern border were more modern and efficient than their Italian counterparts: 300mm-thick steel domes protected concrete roofs of up to 5m thick, while Italian buildings only had domes half that thickness and only able to withstand medium-calibre artillery fire.

The open highlands of the western section of the Front, on the border of the Austrian-held Trentino salient, were ideal for the line of fortifications, whose remains are visible to this day. The well-preserved Belvedere fortress, brainchild of Count Franz Conrad von Hoetzendorf, was a formidable guard of the city of Trento. Built on a sheer cliff overlooking the Valdastico Valley, it was a perfect example of state-of-the-art military engineering.

Conrad, Chief of the General Staff of the Austrian armed forces, knew very well that from this point a deep penetration into the Venetian plain below would cut off enemy forces from the east and win the war. The Belvedere was built between 1908 and 1914.

The fort, which could host a 200-men garrison, was constructed around a three-storey central building, protected on three sides by the cliffs and covered with a 2.6m-thick concrete roof, with access to three heavy batteries, armed with 100mm mortars, two 80mm and two 60mm cannons. The heavy mortars had a range of up to 7km. The fort survived repeated bombardment during the conflict, but never faced a direct attack from the ground.

With the start of military operations, the pre-war doctrine of holding the Front by a series of strongpoints was promptly - and rather ironically - replaced with a more outdated one aimed at holding the line permanently by using terrain morphology itself. This implied the use of high altitudes to obtain all that was needed: from artillery pieces and ammunition to food, water and construction materials.

Aerial railways

The importance of logistics in this first industrial war cannot be underestimated: to keep up the fight, immense quantities of supplies had to be transported to the Front Line continuously and on time.

A whole network of roads, mule tracks and aerial cableways had to be built from scratch, often in combat conditions, on very difficult terrain. Construction techniques developed then are still in use today. The logistic infrastructure had to assure not only the flow of combat material to the Front Line but also, and perhaps more importantly, the delivery of the survival basics.

While railroads were the backbone of the second industrial revolution and influenced military strategy in the second half of the 19th Century, they were not very useful on the Southern Front. Trains could only come so far, and before the war only a couple of railway lines were operating in the region, among them the Padova-Belluno on the Italian side and the narrow-gauge Pusteria - a branch of the main Brennero line - from the north. In order to reach the actual combat theatre, both were extended rapidly at the beginning of the conflict, but even so the logistic network had to be integrated with mountain roads and with the most characteristic feature of this theatre - aerial cableways.

In his war correspondence from the Italian Front, Rudyard Kipling called them “aerial railways”, and rightly so. Cableways were effectively the continuation of the railway network and brought freight to every position in the mountains.

While hundreds of kilometres of roads were built, especially on the Altipiani - the highlands that were the main feature of the western part of the Front - the cableways were a real engineering wonder. They constituted a complex network which could be divided into three sectors. The first, directly connected to the railhead in the rear, was similar to the cableways used in mines. It could carry up to 200 tonnes and was of the non-stop kind, with self-locking carts. 

For the most part, these were three-cable systems with two load-carrying cables and a transmission one. Austria-Hungary was able to enlist the help of the German Alpenkorps to build aerial highways, suspended over the valleys on big wooden lattices and stretching for dozens of kilometres.

To speed up the installation, modular kits, the forerunners of modern industrial building methods, were used. Pre-built elements allowed the engineers to adapt easily to the terrain by assembling the needed components. An operative plant could be completed in a few days. The three-cable systems had a capacity of up to two tonnes. They were mostly powered by diesel engines, but some electric plants existed too.

The last leg of the long journey the supplies had to endure to reach the soldiers was carried out by ‘telefori’ - small mono-cable installations, often built with locally available materials and servicing single positions even on precarious ledges and peaks. One cable and a lone winch were enough, and on many occasions the telefori were manually operated. Let us not forget that the cableways often doubled as communications networks, carrying on their lattices telephone and telegraph cables.

Engineering works

Wherever possible, roads were built. One of the most important engineering accomplishments of the whole Southern Theatre was the so-called ‘Road of the 52 tunnels’ - a mule track built on the Pasubio massif between February and December 1917. This was a key position, because a collapse of the line there would have allowed for an easy penetration of the Venetian plain by the Austrian forces, possibly cutting off the whole Italian army from the rest of the country.

The Front Line split the rocky summit between the two warring sides, but the Italians had a problem: their supply lines were exposed to enemy fire. A new high-altitude road was needed, one that was protected and available all year round.

The task of building it fell on the shoulders of the 33rd Sappers company of the 5th Regiment - part of the growing engineering corps of the Italian Army, which grew from 12,000 men at the beginning of the war to 17,000 men on the day of the Armistice, when one in every four men was an engineer.

The road was to be more than 7km in length, with a vertical gradient of nearly a kilometre. Its width was to be enough to allow the transit of two mule trains in opposite directions. Hand tools, such as picks and axes, were used, but most of the work was done with explosives and pneumatic sledgehammers, often by soldiers literally hanging from cliffs. The hammers were powered by a central compressor with individual wires for each tool.

The road’s most striking feature, however, was the tunnels - all 52 of them dug into rock. Some of the galleries had the form of a corkscrew with up to four coils worming into the mountain. Being pressed for time, the engineers had to dig each gallery from up to ten points at the same time. The track gained altitude rapidly and ended up hugging the cliff in its final span. The road was supplemented with safety rails, resting areas, avalanche protection devices and a truly monumental tunnel entrance.

The mine war

During the First World War, engineers were meant not just to build their own installations, but also to destroy enemy structures. Long underground tunnels were dug with the sole aim of getting underneath the enemy’s strategic positions, mine them and blow them up.

The mine war changed the appearance of many an alpine peak, levelling their tops. The challenges the soldiers on both sides faced are hard to imagine. Under the Dolomites’ tract of the Front alone, dozens of large mines were uncovered in November 1917. A network of frequently intertwining underground galleries, packed with explosives, crisscrossed the body of the mountain, their aim to entomb the enemy.

Like in many other bloody First World War battles, no meaningful territorial or tactical gain was achieved in this alpine version of the war of attrition of which civil engineering seemed the only benefactor. *

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