The Italian advance towards Val Badia, Val Pusteria and Brennero was halted at the
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,
di Lana and
At the Cinque 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.