On 23rd May 1915, the Kingdom of Italy declared war on the Austro-Hungarian Empire.
The Italian Army occupied Cortina, thus ending four centuries of Hapsburg Empire rule there.
The Austro-Hungarian troops withdrew onto the Lagazuoi to defend the Badia Valley and South Tyrol.
From that moment onward, the mountains of the Lagazuoi 5 Torri area became the theatre of an incredible war fought at high altitude.
The trenches of the two opposing armies wound along the ridges.
Today, thanks to the collaboration of our erstwhile enemies, the Italian and Austro-Hungarian emplacements on the mountains have been restored.
Out if this arose the most widely extended museum of the Great War, comprising the three open-air museums of the Lagazuoi, the 5 Torri and the Sasso di Stria, and the Museum of the Tre Sassi Fort.
The Italian advance towards Badia Valley, South Tyrol and Brenner was halted at the Valparola Pass in the face of the Austrian trenches.
Realising the futility of surface to surface attacks both armies began to excavate galleries and caverns in the mountain with the intent of blowing up their adversaries and fortifying their own positions.
Inside Lagazuoi today it is still possible to see the long tunnels, wooden huts, emplacements and trenches which form the open air museum of the Great War.
The trenches of the two opposing armies snaked their way along the summits of the mountains around Lagazuoi: Tofane, Castelletto, Great Lagazuoi, Sasso di Stria, Settsas , Col di Lana and Marmolada .
At the 5 Torri (Five Towers) and Averau spread the second Italian line with artillery emplacements and floodlights to light up the mountain side of Lagazuoi.
It was soon clear to both sides that the best protection from enemy artillery fire was provided by the mountain itself and so began the excavations with emplacements and encampments transforming Piccolo Lagazuoi into a natural fortification.
The only way to conquer the enemy's emplacements was to blow up a mine underneath them.
Five mines were detonated: four by the Austrian soldiers against the Martini ledge and one by the Italian troops in order to conquer the“Anticima” emplacement on the peak of the Lagazuoi.
The soldiers of the two armies lived in the mountain until 1st November 1917. After the Battle of Caporetto the Italian army was defeated and had to abandon the front line on the Dolomites.