The Fifth Battle of the Isonzo was fought between Austria-Hungary and Italy as part of the coordinated Entente response to the German Verdun offensive in France. Nothing much was achieved before the Austrians launched their own Tyrolean offensive, driving out of the mountains across the Asiago Plateau sector of the Trentino Salient with the intention of breaking through to the coastal plain and severing the Italian communications running east to the Isonzo and Alpine fronts. Though the Italians managed to check the Austrian advance, the offensive had political consequences in Italy: the Antonio Salandra cabinet fell, and Paolo Boselli became Prime Minister.
With a 48-hour bombardment, the Fifth Battle of the Isonzo concentrated on the middle reach of the river between Tolmein and Mount San Michele. This involved the usual bloodbath on the hill of Podgora, where the Austrian units resisted with their normal doggedness. The Italians gained one hundred metres of altitude on Mount Sabotino – a genuine achievement, made possible by long preparation over the winter. On San Michele, the Third Army gained ground near the hamlet of San Martino, only to lose it when the Austrians used tear-gas shells. Offensives around Tolmein and on Mount Mrzli met with no better success.
The Asiago attack was conceived by Conrad von Hötzendorf, the Austrian Chief of the General Staff, who was desperate to stamp down on the Italians, whom he still considered as traitors to the cause of the Central Powers. This planned offensive would cause a considerable amount of friction with Erich von Falkenhayn, the German Chief of the General Staff. He believed that it was a distraction from the main battle against Russia and France.
The Austrians attacked. This was an amazing venue for modern warfare, the jagged ridges of the great mountains liberally slashed by yawning chasms, the splintering rock magnifying ten-fold the effect of bursting shells to produce a spray of deadly splinters. The heavy Austrian guns had a terrible effect on the Italians, who were forced back across the Asiago Plateau. For a while it even looked as if the Austrians might break through to the Po River and the coastal plains.
By this point, Cadorna had survived a government bid to unseat him. Following the loss of Arsiero and Asiago, Salandra sought the King’s backing to oust the Supreme Commander. The King indicated that, if Salandra had full cabinet support, he would not stand in the way. However, the general had public support. When parliament opened, deputies blamed Salandra for the crisis so narrowly averted. The Prime Minister hit back, accusing Cadorna of failing to prepare his defenses. Most deputies backed the army, and Salandra lost a vote of confidence. ‘Hanged in his own noose,’ was Cadorna’s pithy comment.
A mixture of exhaustion and the knock-on effects of the successful Brusilov offensive on the Russian Front began to impact the Austrian effort. Conrad was forced to divert divisions to help shore up the Eastern Front, and the Austrians slowed to a halt. Taking advantage of this, the Italians managed to divert some troops from the Isonzo front and counter-attacked hard, regaining much ground as the Austrians fell back to their prepared defensive positions. Falkenhayn was furious, for by diverting troops and guns from the east, Conrad had enabled the Russian General Aleksei Brusilov to launch a successful offensive.
By the middle of June, the offensive was slowing down in the face of Italian reinforcements. Italy’s entry into the war, which had been planned for the sole purpose of draining off Austro-German resources, was now moving in the opposite direction. The reverse flow, of Allied troops into Italy, had not yet begun, but the danger signals were there. But once again, the Russians came to the rescue with a grand offensive in the East, and by the start of the Somme in France, Austrian troops had been driven back from their forward positions around Arsiero and Asiago.