The Italian front and the Trentino offfensive

Bearing little resemblance to today's borders between Italy and her Austrian and Slovenian neighbours, the WW1 front snaked for well over 400 miles (only approx. 200 miles as the crow flies). From Switzerland and its Alps in the west to the plains approaching the Adriatic Sea at Montfalcone just north of Trieste, this serpentine line created by Alpine topography held two enormous salients. The narrower Austro-Hungarian salient contained the Trentino region, subject to multiple Italian attacks in 1915. The broader Italian bulge was formed by the Dolomites and the Carnic Alps - difficult terrain for any strategic moves. This meant that the Italian offensive ambitions (and the majority of their forces) were mainly confined to pushing eastwards across the plains below the Alps. Many great rivers flow across this region from the mountains to the Adriatic, including the Po and Adige south of Venice, and the Isonzo at the eastern extreme. The Isonzo (today the Slovenian river Soca) became one of those infamous WW1 focal points: fought over time and time again with great losses.

  The vulnerability of a typical salient worked both ways for the Trentino. Although on paper it was exposed to Italian attack on all three sides, the Austrians held the high ground and all the mountain passes, making it hazardous for the Italians to advance over hostile steep terrain. In fact, this salient posed a greater threat to Italy, bulging into Italian territory and menacing the rear of the main Italian communications leading eastwards to the Isonzo region. This threat had caused the Italian 1^st and 4^th armies to make frequent difficult sallies against the Austrian positions during the winter of 1915-16. 

Marmolada in the Dolomites.
Hard to imagine this as a war
front - under 30ft of snow - in 1916

The physical and mental challenges of conducting war in the wintry conditions of the Alps must have been harrowing. Near Cortina in the Dolomites, the Italians tunneled into the mountain for three months, and in April mined a crucial mountain post and blew the Austrians out of it, creating a 150 foot crater in the mountain top. Further west, extraordinary feats by the Alpini – Italian mountain troops – captured small parts of the Trentino salient. In the east, Italy made further pushes towards Gorizia, on the Carso plateau (see map), and the upper gorges of the river Isonzo. Overall, their gains were small but sufficient to threaten important Austrian rail networks. The Austrians needed to counter these threats, and had been making plans to do so.

Upper Isonzo 1916.
Just how did they do it?

The Austrian Commander in Chief, Conrad von Hotzendorf, had been the most belligerent player in the build up to war in 1914. Starved of success, and close to humiliation in Serbia and Galicia, he got on badly with his German ally and opposite number, Falkenhayn. In December 1915 the latter had refused support for Conrad’s proposal to breakthrough from the Trentino, roll up the Italian main forces from the rear and put Italy out of the war. Falkenhayn was too pre-occupied with his own plans to reinforce Verdun from the Eastern Front to offer resources to a man whose abilities he disparaged. By spring however, the Austrians had gathered sufficient strength to try their assault without German support. An advance to the Venetian plain would cut off both main railway lines to the Isonzo.

The Italians were aware of an Austrian build up, but did not expect such a major counter-offensive as was launched upon them on 14^th May. A major bombardment, including 800 Howitzers blasted out from the Trentino salient. After eight days of fierce fighting the Austrians were approaching a key objective of Pasubio, north of Vicenza. Desperate defence held them off there, and at Asagio. Further east, heavy fighting in the passes came to a climax on 30^th May, when Austria lost 7000 men on that day alone. By 3^rd June they had reached the furthest point of their invasion, only 18 miles from Vicenza and the main lines. But they had exhausted their strength, and on that day the Italian Commander in Chief Cadorna announced confidently that the invasion had been halted. He was proved correct.

Luigi Cadorna, Italian C-in-C.
His forces only just managed to
hold off the Austrians

Austria’s major gambit had come close to success, but had failed. Italy was still in the war. Furthermore the cost of packing nearly a million troops and their equipment into the salient had been to weaken significantly their northern forces in Galicia. Although this front had been comparatively quiet through the winter, the Russians were preparing for the next major strategic campaign of 1916 – the Brusilov Offensive.