The White War was a sector of the Italian front of World War I that saw high-altitude fighting among the Dolomintes, the Ortles-Cevedale Alps, and the Adamello-Presanella Alps from 1915 to 1918.
At the outbreak of World War I, Austria was in control of the Trentino border region, which extended southwards towards the River Po and enabled the Austro-Hungarian Army to strike towards the lower Adige and Mincio to cut off Veneto and Friuli-Venezia from the rest of Italy. Road and rail systems did not allow the Italian general Luigi Cadorna to mass his forces near the favorable Kreuzberg Pass, forcing him to instead concentrate on the Isonzo front further east, where he hoped to make a decisive breakthrough. The Italians closed off the northern passes, leading to both sides maintaining a static posture rather than the Austrians threatening the industrial cities of Lombardy or the Italians invading Tyrol. Both armies built a network of roads, mule tracks, and pathways, employing 900 porters to maintain garrisons of 100 men on 3,000m peaks. General Roberto Brusati's Italian 1st Army, consisting of Vittorio Camerana's III Corps and Florenzio Aliprindi's V Corps, was deployed to cover the Alpine front from Verona, reinforced by that fortress' garrison. General Luigi Nava's Italian 4th Army was deployed to the Dolomites sector. Meanwhile, the Austro-Hungarians established sectors facing the Italian armies, and they were later reinforced by the German Alpenkorps.
While the Italians enjoyed numerical superiority, they did not take the offensive on the alpine front, as they lacked intelligence about the strength of Austro-Hungarian numbers and were risk-averse. Likewise, the Austro-Hungarians' goal was merely to hold off any Italian invasion, while their resources were directed to Eastern Galicia on the Russian front. Conrad von Hotzendorf neglected the defense of the Dolomites in favor of strengthening his position on the Asiago plateau, as a base from which to attack the Veneto. Both sides established mountain fortresses and excavated caves, tunnels, trenches, walkways, shelters, and underground depots, creating entire underground towns relatively safe from enemy fire.
By April 1915, about 32,400 Austro-Hungarians were defending the Tyrol, while 13 battalions of the German Alpenkorps arrived on 26 May; meanwhile, the Italians had between 100,000 and 120,000 troops to defend their northern front. Significant battles occurred at the Sasso di Sesto and the Marmolada glacier throughout the campaign, and both sides suffered heavy losses while fighting in dismal conditions. While the Italians abandoned the Marmolada sector following the Battle of Caporetto, a final Italian attack on the Tonale Pass on 1 November 1918 resulted in the mass surrender of Austrian troops in the Adamello-Presanella sector, and the Italians advanced into the entire Val di Sole and on to Trento. The August 1918 Battle of San Matteo was the highest-altitude fighting seen anywhere in the war, as unusually hard ground made it almost impossible to dig trenches and tunnels or to fight. By November, the Austro-Hungarian surrender led to an Italian victory on one of the most brutal fronts of the war.