Italy’s entrance into the Great War on May 23, 1915, had opened up a new front stretching 600 kilometers—most of them mountainous—along Italy’s much-contested border with Austria-Hungary in the Trentino region. Upon declaring war, the relatively ill-equipped Italian army immediately advanced into the South Tyrol region and to the Isonzo River, where Austro-Hungarian troops met them with a stiff defense. The snowy and treacherous terrain made the region poorly suited for offensive operations, and after several quick Italian successes, combat settled into a stalemate.
Luigi Cadorna, the chief of staff of the Italian army, determined that his forces could most easily make territorial gains against the enemy in the region of the Isonzo, a 60-mile-long river running north to south just inside the Austro-Hungarian border with Italy (present-day Slovenia) and flanked on either side by mountains. The Italians launched their first offensive in the region, known as the First Battle of the Isonzo, in June 1915.
The Seventh Battle of the Isonzo, fought between September 14 and 17, 1916, attempted to repeat the successes of the sixth and most successful Italian offensive, fought one month earlier. In that battle, the Italians had forced the Austrian forces back some five kilometers before Cadorna called off the offensive, claiming success. Unfortunately for the Italians, the follow-up attack in September was less effective: though the Italians captured several mountain peaks, including the 7,723-foot Mount Cardinal in the Trentino, the Austrians managed to hold the line, and actual Italian advances were minimal, at a cost of heavy casualties.
The treacherous terrain surrounding the Isonzo River would see no fewer than 12 battles from June 1915 to November 1917; these battles, culminating in the disastrous Battle of Caporetto, or the Twelfth Battle of the Isonzo, cost the Italians some 300,000 casualties—fully half their casualty total during the entire war.