Battlefield Dolomites: How Geology Shaped Mountain Warfare

The Great War (1914-1918), fueled by technological innovations and the industrial revolution, was a new type of war. Every corner of the world was touched, from the sea to the highest peaks of the Alps. Entire landscapes were devastated by high-energy explosives.

The Lagazuoi overlooking the Falzarego-Pass in the Dolomites. During WWI the Austrian front-line followed the crest of the mountain, the Italians occupied the ridge in the middle of the cliff.

May 23, 1915, Italy declares war on Austria-Hungary, bringing the war also into the Dolomites. The Austrian military high command fears that the Italian army now can reach the capital city of Vienna in just a few days, so the local troops are ordered to fortify the most important routes and mountain passes in the region. There was no experience with combat in such an extreme environment. Braced by snow-capped mountains, neither side can find a way to dislodge their enemy.

Simplified geological map of the Alps.

Of strategic importance was the Falzarego-Pass. The nearly vertical cliffs of the Lagazuoi, a 2.835 meter-high mountain, overlook this pass. The Austrian forces fortified the mountain summit, attacked from below by the Italian forces. It was almost impossible to directly attack the enemy, defending himself with machine-gun nests and taking shelter behind rocks. The military tried to solve this problem with tactics first successfully adopted in the plains of France. Tunnel warfare involves the construction of long tunnels beneath the enemy lines, large quantities of explosives are then detonated to form a breach. In the Dolomites, explosions were also used to trigger rockfall and kill the enemy.

Machine-gun nest overlooking the Lagazuoi, hidden in a cavern built into Cassian-Dolomite.

In July 1916, to reach the Italian position located on a rock ledge (formed by a large fault) on the southern side of the Lagazuoi, the Austrian army started to dig a tunnel from the northern side. Adopting a similar strategy, the Italian army tried to dig a tunnel beneath the peak of the Lagazuoi. The Austrians detonated the first mine on January 14, 1917.

The Lagazuoi is composed of the Cassian-Dolomite, the dolostone core of a former Triassic reef. The relative plain summit of the Lagazuoi is formed by erodible marl deposits of the Heiligkreuz- and Travenanzes-Formation. The Falzarego-Pass and nearby Valparola-Pass are located in the former basin sediments (soft sandstone and marl formations) separating the Lagazuoi reef from nearby carbonate platforms.

Cross-section through the Lagazuoi. a) San Cassiano Fm; b) shallow-water deposits of the San Cassiano Fm; c) Cassian Dolomite; d) Heiligkreuz Fm ; e) Dibona sandstone, (1) lower member of marls, calcarenites and sandstones; (2) upper carbonate beds; f) Travenanzes Fm; g) Dolomia Principale (Trombetta 2011).

The hard dolostone is deformed and broken by tectonic forces. However, the rock was much harder to excavate than expected. Working incessantly the miners were able to advance 9 meters a day. Between 1915 to 1917, when the war in the Dolomites ended, more than 34 such tunnel blasting operations were attempted, 20 by the Italian and 14 by the Austrian military.

WWI trench on the Lagazuoi summit dug into the softer Heiligkreuz- and Travenanzes-Formation.

In 1917, shortly before detonating a mine, the Italian soldier Luigi Panicalli wrote: “I realize that in just some moments the results of all the months of work and suffering will become visible. I’m like petrified. In the last moments my thoughts are by the enemy – poor guys – do they feel death approaching? Do they know, that the enemy is inside the mountain, ready to blast them from the mountain down into their graves?“

Detonation of a mine on the Lagazuoi by the Italian forces May 22,1917, to dislodge the Austrain forces still occupying the summit. 41 soldiers were killed.
Crater and debris formed by a mine on May 22, 1917.
Crater and debris formed by mine detonation on June 20, 1917.

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Autor: David Bressan

Bressan-Geoconsult bietet geologische Dienste im Alpenraum an, mit Schwerpunkt auf geologische Kartierung, Betreuung von Bohrungen, Quartärgeologie, Hydrogeologie und Baugeologie. Kontakt: david@bressan-geoconsult.eu

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