On May 12 the Italians began an offensive along the entire Isonzo line. Although the offensive claimed 100,000 German and Austrian casualties, it did not bring the Italians any closer to their objective of Trieste.

Internal unrest in Italy, caused by the strain of war on the economy, made a speedy victory by Italian forces desirable. A new offensive, which resulted in the 11th and last Battle of the Isonzo, was launched August 18. The first rush on August 19 carried the Italians into the Austrian front-line trenches along the entire 23-mile (37-km) front from Plava to the sea. For two weeks fierce fighting raged around Monte San Gabriele and on the Bainsizza Plateau. The Italians took San Gabriele September 4. The Austrian position was shattered, and the Austrians were saved only by the fact that the Italian troops outran their artillery support and supply lines. The fighting died down by September 12.

By this time, Ludendorff had become the real power in the German high command. Realizing the potentially disastrous situation on the Isonzo, Ludendorff sent six German divisions, under the command of General Otto von Below, to reinforce the Austrians and attack the Italians. On October 24, the German and Austrian forces struck near Caporetto, a village on the Isonzo. After a short, intense bombardment, German infantry came pouring down on the Italians and routed them. At Tolmino, farther south, the Austrians swept through the Italian lines on the first rush. The whole 16-mile (26-km) sector collapsed within a day.

General Armando Diaz became the Italian commander on November 7, replacing General Cadorna. By November 10 Italian troops, reinforced by French and British units from France, regrouped and entrenched themselves on the Piave River, 60 miles (97 km) southwest of Caporetto. During the fighting at Caporetto, the German and Austrian forces captured 2,300 guns and took almost a quarter of a million prisoners. In addition, an estimated 300,000 Italians deserted.