Start of the First Battle of the Isonzo

The British chronology of the war records under 29 June 1915 the start of the First Battle of the Isonzo. The Italian official history and most historians, however, date its beginning to 23 June. At dawn that day the Italian artillery opened fire along the whole front on the Soča, from the mountains above Tolmin to the Adriatic coast, and the infantry went into its first attacks. By 29 June, therefore, the battle had already been going on for a week, and its first stage was drawing to a close without a decision. We have not been able to establish where the date in the British list came from.

Cadorna’s plan

In the month since crossing the frontier the Italian army had advanced slowly. It had occupied the land between the old frontier and the Soča, Monfalcone and the summit of Krn, but had not managed to take the strong positions on the river. In the meantime General Svetozar Boroević’s Fifth Army had manned the hills of the Gorizia bridgehead and the edge of the Karst plateau and surrounded its trenches with barbed wire. General Luigi Cadorna decided to break this line with a single great offensive. In the north General Pietro Frugoni’s Second Army was to attack at Plava and the Gorizia bridgehead, and in the south the Duke of Aosta’s Third Army was to cross the Soča and break onto the Karst. The Italians had more than a twofold numerical superiority, but little heavy artillery and ammunition.

The first week

Most happened on the lower Soča. On the morning of 23 June the Siena Brigade crossed on pontoons the de Dottori canal, whose waters the Austrians had earlier let flood the plain, and moved towards Sagrado and Redipuglia. The Pisa Brigade spent two days crossing the Soča itself, first by boat to an islet in the middle of the river and then to the left bank. On 25 June Italian engineers repaired the bridge at Sagrado, the Pisa Brigade crossed to the other side, and the Bologna Brigade took the village of Castelnuovo on the edge of the plateau. This was the most important gain of the first week. Further attacks on the hill of San Michele and the village of San Martino del Carso on 26–28 June, however, were held up in front of the wire and were halted.

On the other sectors the results were even more modest. At Plava brigades of the Second Army stormed the Austrian positions above the bridgehead in vain for several days. In front of Gorizia the infantry advanced on 24 June against the hills of Sabotino and Podgora before the artillery had had time to destroy the wire, and was stopped at the wire. On the southern sector of the front, north of Monfalcone, the Austrians retook the village of Selz on 28 June. On 29 June the Italians recovered it in a counter-attack.

What came next

The first week showed that the defenders, though more than twice as weak, could stop an attack thanks to trenches cut into the rock, barbed wire and machine guns. The Italian artillery bombardment was too short and too weak to destroy the obstacles, and the infantry did not have enough wire cutters. Cadorna, however, did not break off the offensive. In the last days of June and at the beginning of July the Italians renewed their attacks along the whole front, from the Tolmin bridgehead to the hills above Redipuglia. The heaviest fighting took place on 4 and 5 July on Monte San Michele, on the hill of Sei Busi and at Gorizia. On 7 July Cadorna halted the battle. It cost the Italians about 15,000 and the Austrians about 10,000 killed, wounded and missing, and did not bring a breakthrough.