On June 10, 1917, Italian troops launch a renewed assault on Austro-Hungarian positions in the mountains of the Trentino region in northern Italy, on the border with Austria.
The formidable nature of the northern Italian terrain—four-fifths of the 600-kilometer-long border with Austria was lined with mountains, with several peaks rising above 3,000 meters—made the Italian, of all the fronts during World War I, the least well-suited for battle. Nevertheless, upon their entrance into the war in May 1915 on the side of the Allies, the Italians immediately took the offensive against Austria in the Trentino, with little success. By the end of 1915, after four battles fought on the Isonzo River, in the eastern section of the Italian front, Italy had made no substantial progress and had suffered 235,000 casualties, including 54,000 killed.
The Tenth Battle of the Isonzo—by the end of the war there would be 12—in May 1917 had met with a similar lack of success for the Italians. A major Austro-Hungarian counter-offensive launched on June 3 reclaimed virtually all of the ground Italy had gained; Italian Commander-in-Chief Luigi Cadorna shut down the attacks on June 8.
Two days later, the increasingly frustrated Italians renewed the battle, attacking six mountain peaks in the Trentino. Italian deserters had revealed details of the assault to the Austrians, however, and they were able to counterattack successfully and hold their positions. The Italians did manage to capture one mountain peak, however—the nearly 7,000-foot-high Mount Ortigaro—and take some 1,000 Austrian prisoners. Two weeks later, the Austrians seized control of Ortigaro again, taking 2,000 Italian prisoners. By the end of June, after three weeks of heated battle on the mountain peaks and passes, the lines of territory had barely changed, at the cost of 23,000 Italian and nearly 9,500 Austrian casualties.