End of the Trentino offensive

The British chronology of the war records under 3 June 1916 the end of the main Austro-Hungarian offensive in the Trentino, which had begun in mid-May. It is a conventional date. On that day Austro-Hungarian mountain riflemen took the main summit of Monte Cengio, the last mountain on the south-western edge of the Asiago plateau, and the Italian Supreme Command announced in its war bulletin that the enemy would not pass the barrier of the mountains. The Austrians, however, went on attacking. According to their official history, the last attacks on the plateaux took place between 12 and 16 June, and the order to go over to the defensive reached the Army Group headquarters in Bolzano only on the evening of 16 June.

The fight for Monte Cengio

Monte Cengio (about 1,350 metres) rises above the Astico valley, where the plateau of the Seven Communes falls steeply towards the Venetian plain. From the end of May it was defended by General Giuseppe Pennella’s Italian Granatieri di Sardegna brigade, supported by the remnants of other brigades. On the evening of 31 May a Salzburg battalion of the 59th Infantry Regiment broke onto one of the domes of the massif and held it despite counter-attacks. The Austrians believed they had taken the summit, but it soon turned out that the main dome was still in Italian hands. On the night of 2–3 June the Italian 32nd Division, sent up from the reserves, tried to recover the lost ground and was repulsed.

On 3 June the Austro-Hungarian artillery opened fire before noon. According to the Austrian official history, at about half past twelve a battalion of Carniolan mountain riflemen, which had strayed from its assigned direction, unexpectedly broke into the fortifications on the main summit, partly hewn out of the rock. Behind it came soldiers of the 59th Regiment and Carinthian mountain riflemen. On the summit itself more than 1,400 prisoners were taken. Italian studies add that the attack came at the moment when the Modena brigade was relieving the exhausted grenadiers in their positions. In the evening two more battalions of mountain riflemen pushed the Italians off the ridge as far as Monte Barco. According to Austrian figures, the Italians lost about 300 killed and more than 2,000 prisoners on Monte Cengio and Monte Barco that day. The defenders withdrew through the Canaglia valley to the line of Monte Paù and Monte Busibollo. After this defeat Cadorna removed the commander of the 32nd Division, and on 4 June General Ettore Mambretti took command of the troops on the plateau.

The success, however, did not bring a breakthrough. On the same day the Austro-Hungarian 34th Division took the Busibollo hill south of Cesuna, but had to abandon it under flanking fire from Monte Lemerle. Beyond Monte Cengio the ground did not open into a valley but turned into wooded karst, in which the Italian positions were hard even to spot, let alone destroy by fire.

Why the attack stalled

On the western wing the offensive had slowed down even earlier. The Italians held the main ridge of the Pasubio (PL) massif and the Coni Zugna mountain above the Adige valley, and they had repulsed the heaviest attacks on the Buole pass at the end of May. The Austrians had to haul heavy guns over ruined roads, and every few days rain and fog immobilised the artillery on which each new attack depended. Meanwhile the Italians already had a new army behind them. On 2 June five corps of the 5th Army, formed on 21 May from troops brought from the Isonzo, assembled on the plain near Vicenza. From it Cadorna had already sent the whole of XXIV Corps into the mountains.

Luigi Cadorna wrote after the war that it was on 2 June that he became certain the enemy would not come down into the plain. On that day he ordered the 1st Army to seize the initiative: first to consolidate the front on the Asiago plateau, and then to strike the flanks of the Austro-Hungarian wedge. On 3 June he ordered the recapture of Col Santo north of the Pasubio, and the war bulletin of that day announced to the Italians that the offensive had been halted. Even the loss of Monte Cengio on the same day did not change this assessment.

Over the whole offensive there also hung a threat from the east. From 19 May the Italians had several times asked Russian headquarters for an attack that would relieve their front. The Chief of Staff, General Mikhail Alekseyev, speeded up the preparations and set the start of the South-Western Front’s offensive for the beginning of June. According to the Austrian official history, the Russians announced this attack to the Italians on 1 June. In Galicia and Volhynia there was now a shortage of the troops that Franz Conrad von Hötzendorf had taken to the Tyrol. The next day, 4 June, the Brusilov offensive began. Within a week it forced Conrad to send the first divisions from the Tyrol back east and to limit the aims of the attack against Italy.