After the crushing loss suffered by the Austro-Hungarian Empire at the battle of Sadowa in 1866, The Empire lost more lands in Italy to the Kingdom of Savoy. The entire Veneto added to earlier losses of Lombardy and smaller duchies in central Italy like Tuscany. Austria’s old defense system centered around the forts of the Quadrilateral. Those forts were all given up after 1866 with the loss of the Veneto and Friulian. A totally new defensive system became needed – enter the Kärtner Sperren.

In the far northeast of Italy, Austrian fortifications were not as elaborate as those in South Tyrol. Here, a modern fort system developed in the early 20^th century to both defend and to serve as a potential base for offensive operations against potential Italian aggression – even though, Italy supposedly was an ally to Austria-Hungary.