Between the 1860s and the First World War the Kingdom of Italy built a number of fortifications along its border with Austria-Hungary. From 1859 the fortified border ran south from Switzerland to Lake Garda, between Italian Lombardy and Austrian South Tyrol. After 1866 it extended to include the border between South Tyrol and Veneto, from Lake Garda to the Carnic Alps. This frontier was difficult to defend, since Austria-Hungary held the higher ground, and an invasion would immediately threaten the industrial and agricultural heartlands of the Po valley. Between 1900 and 1910, Italy also built a series of fortifications along the defensive line of the Tagliamento to protect against an invasion from the northeast. The border with Switzerland was also fortified in what is known as the Cadorna Line.

The Cadorna Line, officially the Northern Frontier, was the Italian defensive system on the northern border facing Switzerland, designed and built between 1899 and 1918. Its purpose was to protect the Po Valley and its main industrial centres from an attack by France, Germany or Austria-Hungary violating Swiss neutrality.