Trentino offensive begins

The British chronology of the war states that the Austro-Hungarian offensive in the Trentino began on 14 May 1916. That date is a convention. According to the Austrian official history, the main blow from South Tyrol, from the lands of today’s province of Trento, began only on 15 May: at six in the morning the batteries on the plateaux of Folgaria and Lavarone opened fire, at nine they moved on to destructive fire, and around noon the infantry went in to the assault. Many Italian works, however, write that the roar of the guns was heard over the Trentino as early as the afternoon or night of 14 May. The discrepancy arises largely because shooting really did begin that day, only not where the blow was to fall.

A feint on the Isonzo

The Chief of the Austro-Hungarian General Staff, Franz Conrad von Hötzendorf, had for many weeks been hiding from the Italians where he would strike. He brought divisions to Tyrol from the Isonzo, from the Balkans and from the Eastern Front, and in March ordered raids and feint marches to convince the enemy that an offensive was being prepared in the east. For the day before the attack a final deception was prepared. On the afternoon of 14 May the artillery of the Austro-Hungarian 5th Army opened fire along the whole Isonzo front, from Mount Krn to the sea. Infantry raids were to follow at night, and at dawn aircraft were to bomb railway junctions in Venetia and Italian headquarters. All this was so that the Italians would believe the great attack was beginning on the Karst.

At nine in the evening, after a short bombardment and the firing of a mine dug under the Italian trenches, units of the Austro-Hungarian 17th Division captured about 300 metres of Italian trenches on the Karst plateau, west of San Martino, and beat off counter-attacks. At Tolmin assault detachments broke into the Italian trenches, destroyed them and returned with prisoners. A night attack by Landsturm troops on the shipyard at Monfalcone failed because it waited for the navy’s seaplanes, which arrived late, although an advanced Italian position in front of the works was taken. In Carinthia rain and fog delayed similar operations until the next day.

The last hours before the assault

Meanwhile in Tyrol Archduke Eugen’s Army Group stood ready to attack: fourteen divisions, about 220,000 men according to the Austrian official history, and more than a thousand guns, including 30.5 cm mortars and 38 cm and 42 cm howitzers. The attack had been prepared since February, but deep snow on the plateaux postponed it several times. It was originally to begin on 10 April, then in the first days of May, and finally on 17 May. Only after urging from headquarters at Teschen did the commander of the 11th Army, General Viktor Dankl, finally set 15 May. At first only two corps were to attack: the XX Corps of the heir to the throne, Archduke Charles, on the Folgaria plateau, and VIII Corps south of Rovereto. III Corps on the Vezzena plateau was for the time being to support its neighbour with artillery fire.

The Italians knew something was afoot. Since March reports had been reaching them of a concentration of troops in Tyrol, and at the end of March and in April at least two deserters from the Austro-Hungarian army came over to them. The Chief of the General Staff, Luigi Cadorna, reinforced the 1st Army defending this sector, but did not believe in a large-scale offensive in such difficult terrain and kept his main reserves on the Tagliamento, with an eye to his own attack on the Isonzo. According to his later figures, the 1st Army had 176 battalions and about 850 guns between Lake Garda and the Brenta. On 8 May Cadorna removed its command from General Roberto Brusati, who had been raising the alarm about the threat and demanding reinforcements, and gave it to General Guglielmo Pecori Giraldi. The new commander had a week to acquaint himself with the front and expected the main blow in the Valsugana valley, where there had been heavy fighting in April. On the Folgaria plateau, where the real blow was to fall, a single division with 15 battalions was holding the line.

The next morning the fire of more than 350 guns fell on XX Corps’ six-kilometre sector of the front. By the evening of 15 May the Austrian Kaiserschützen and infantry had taken the first Italian line on the ridges of Costa d’Agra and Monte Coston, and near Rovereto the troops of VIII Corps began climbing the Zugna Torta ridge. The Austrians called this attack the spring offensive or the South Tyrol offensive; the Italians remembered it as the “punitive expedition” (Strafexpedition). The fighting on the plateaux lasted more than a month and forced Cadorna to bring a whole new army from the Isonzo front.