The north-western Austro-Italian alpine front. A general overview.

The main battles of World War I on the Austro-Italian front were fought on its eastern portion, along the present Slovenian-Italian border and along river Piave, in the Venetian flat, after the Caporetto breakthrough.
Other important battles were fought in the central portion of the front, over the mountains and plateaus which dominate the Venetian flat on their southern side and the town of Trento on the northern side.
The western segment of the front, going approximately north to south from Switzerland to Garda Lake, was of very little strategic importance.
Deep in the heart of the Alps, only three roads connected Italy and the Austro-Hungarian Empire along 80 km of borderline. Even in case of a massive breakthrough along one of these roads, both armies would have had to march along 30 km of narrow valleys before reaching any place of some strategic importance. The front line there, remained then more or less unchanged from May 1915 to November 1918.
The border started at Stelvio Pass (2759 m) and was continuously over 3000 m for more than 30 km in the Ortles-Cevedale Group to Tonale Pass (1895 m), where it went up again over the glaciers of the Adamello Group for some 20 km and than down on lower but wild and rugged mountains to the Idro and Garda Lakes.
The need to cover a front line at such altitudes, without any previous experience, created new and unexpected problems both tactically and logistically.
War plans for the north-western alpine front were essentially defensive on both sides. As the war started on May 24 1915 the Tiroler Standschutzen were quicker than the Alpini in occupying the borderline and the highest positions along the border, from Switzerland to Tonale Pass, including Stelvio Pass and the surrounding tops. This is well explained by the large local autonomy that these formations had.
In the first months of war very few troops were available in this region so that only the most important and accessible positions had a permanent garrison.
While the troops were being deployed along the front line in summer 1915, several kilometres of the front on the highest glaciers were unmanned and just patrolled from time to time. This caused the first peculiarity of the war in this area. On both sides these patrols were lead by a few local professional Alpine Guides, usually enlisted as non commissioned officers. They all knew each other and were sometimes good friends: before the war they were just the villagers of the next valley!
In the summer of 1915 it happened that Italian and Imperial patrols met on a mountain top, many hours of walk away from the nearest officer, and sat together to share their lunch! These meetings are documented in personal memories and oral tradition.
A long series of such "unofficial" meetings took place in this area all along the war time, even when the war started to be a "real" war. Moreover a sort of chivalry seems to have persisted at all levels. A couple of examples: the Italian artillery avoided bombing the relief squads when a large Imperial barrack took fire in march 1917 near Trafoi and an Imperial officer asked the Alpini near the top of Monte Cristallo to avoid staying so exposed, because his command had asked him why they were not shooting at such easy targets.
The main reason for the long time needed to permanently occupy and garrison the highest positions was the logistics. Many valleys had no roads, but just narrow paths to reach the shepherd's summer huts.
Most strategic positions needed several hours to be reached from the nearest village, often without any path and intermediate rest places. This situation also slowed the deployment of artillery.
During the first summer of war there was very little fighting. Both armies dedicated their efforts in exploration and reconnaissance on the highest glaciers and in creating a logistical structure to survive the incoming winter and accommodate more troops and artilleries for the next summer. Building new roads and creating logistical structures was the main occupation of the troops when not in line. From summer 1916 installing and maintaining cableways also became an important duty.

Great efforts were also necessary to keep the roads and paths clean from snow in winter and from mud in spring. Snow avalanches and landslides also were a continuous danger along the roads. Being isolated from any supply for many days was pretty normal for the front line troops in winter.
Later in the war the Imperials took also advantage of the large number of Russian prisoners. Being them used to the cold of the winter in their country, they were extensively used for hard works and corvees on the Alps.
The useful period for works on the Alps goes approximately from May to October, but is much shorter above 3000 m. A normal summer thunderstorm down in the valley is often a snowstorm on the surrounding tops.
Thunderstorms are extremely dangerous on mountain tops over 3000 m: where there is nothing else around than ice, snow and rocks. Any piece of metal acts as a lightning conductor. During thunderstorms, soldiers had to get rid of their helmets, rifles and ice-axes. Huts, telephone lines, cableways and guns were also dangerous to be too near to.
A second peculiarity of warfare on high mountains was the number of troops, which was very little. Along the first 30 kilometres of front line only 1500-2000 men where deployed on each side. No more than 500 ever were in each first line. Big numbers proved quickly to be more of a problem. In many places there was simply no space to build more than a small hut and accommodate more than a few soldiers with big supply problems anyway. Mules, which are famous for their reliability on high altitudes, were extensively used but could not climb glaciers or ladders. Cableways could not reach any place and were a favourite target for artilleries. Moving many troops in the harsh environment of high mountains was very difficult and seldom was done unseen from the enemy.

A third peculiarity was the great number of tunnels bored in the ice. On the contrary than in Dolomites Alps, the kind of rock in this area is difficult to bore and not very suitable for mines.
Tunnels in ice are easy to dig, but hard to maintain. Glaciers are moving like rivers, only more slowly. Tunnels were mainly used as shelters and connection or access paths where the surface was too exposed to the enemy's view. A few tunnels were more than 2 kilometres long and a couple were more or less successfully dug by the Imperials to attack Italian positions.
The front line as it was in summer 1916 was quite different than in any other place in Europe.
On some mountains the first line trenches were very close to the enemy, 30 to 50 meters away near Stelvio Pass, but in other places they were divided by a valley or a glacier. It was some hundred meters or even a few kilometres of no one s land, pastures or stony ground, glaciers or rocky slopes without any coverage for a large number of troops. Only small patrols, very specialised and well equipped were able to cross the no one's land for sort of "commando" actions, like cutting or even intercepting telephone lines, killing or taking prisoner an advanced sentinel or setting fire to a hut.
When the weather was fine, nearly no position was safe from the enemy's view. Due to the complex geography of the area there was always an enemy's position which was higher or which dominated the access path or look at the rear of the opponents position.

The use of artillery also had to face totally new problems. The need was for a great accuracy due to the small dimensions of targets. In a flat land a shell which goes a little too long is not completely wasted, but when trying to hit a mountain top or a crest, a shell which passes a few centimetres higher falls down kilometres away, causing no damage.
Being accurate was extremely difficult. Winds are not constant on high mountains and do change quickly. Ascending and descending air streams are common and not very predictable and wind direction may differ from one side to the other in a valley. To complete the picture, add the difficulty to stabilise a gun over a soft snowy surface and the need not to waste shells where the nearest depot is many hours away and 1500 metres lower.
The average size of guns was little: judging from the fragments and unexploded shells that literally cover some places, the most common calibre was 65 mm. The 75 mm was relatively uncommon. 120, 149 and 210 mm howitzers arrived in numbers only in late 1917 when the roads and supply facilities were ready to accommodate such big transports. A couple of 305 mm appeared in 1918 on the Imperial side and were used for the counterattack on Monte San Matteo. Those were probably Italian guns captured after Caporetto.

Big howitzers anyway had to fire from very long distance and were not so effective.
Shrapnel shells were extensively used but were generally more bothering than really dangerous, according to diaries and oral memories. Grenade launchers were placed in every front line position and were used sometimes for close defence.
The most effective weapon were undoubtedly machine guns. A single one, well placed in a gallery or hidden between the rocks could inhibit any action on a whole mountain side.
Large empty spaces, long distance from the enemy, poorly effective artillery, very few battles, beautiful landscapes: one can think that life was non so bad for soldiers on the north-western alpine front. It was not. The need to keep the line, regardless of whether conditions, caused more casualties than the enemy's fire. The most common injury were frozen extremities and the second cause of death were snow avalanches. Rock and ice slides, lightning's, falls in precipices and crevasses also contributed to raise the number of casualties.
Modern alpinists do know very well how important is a good, well balanced, high calories diet when having heavy duties at high altitudes for a long period of time. Unfortunately nutrition was not yet a science. The repetitive unbalanced diet, the abuse of water melted from ice and snow, the prevalence of cold meals added to the poor hygienic conditions that every army suffered everywhere created big and unexpected problems, specially for the Imperials who really suffered hunger in 1918.
When the War ended it was already winter on the high mountains. The Imperials simply closed the doors of their huts, made their guns and machineguns unusable and went home to their families. The Italians brought down their guns and machineguns, closed the doors as well and moved forward to take possession of Trentino and SüdTirol, before being demobilised. Most of the equipment was left on site to be recovered on next summer, but mother nature provided a 1918/19 winter extremely snowy and covered many sites permanently for tenths of years. All ice galleries disappeared forever.
As the troops moved away, the local impoverished populations did their best to recover everything which was useful and reasonably easy to reach. Unguarded barracks and huts were spoiled. Even barbed wires and their stakes were taken away.
When the Alpini came back in summer of 1919 to recover the materials, they found that there was little to recover. What was not covered by the snow was already disappeared, except for places which were too difficult to reach or too far to be worth the effort.
With trench maps or direct knowledge of sites, they could recover most, but not all, of the small depots of ammunition and goods along the Italian highest lines, but could find very little around the Imperials positions. Without knowing were to search, digging the snow blindly was simply useless.
Most of the cableways, without maintenance for 8 months, were damaged and unusable, so that most of the ammunition found on the highest positions was simply piled up and exploded. I personally found traces of this in a couple of places were hundreds of cartridges are scattered around, cracked and twisted.

During the following years and up to the Great Depression in Thirties, the retrieval of metals was a way to survive for many poor people who retrieved all shells and their fragments everywhere it was worth the effort.
In recent years, the withdrawal of glaciers and permanent snow coverage, is bringing to the light a number of "forgotten" sites. Huts, dugouts and trenches are slowly appearing in the state they were in November 1918, revealing the "everyday" life of soldiers.