First Battle of the Isonzo

Italian Forces, 750,000
General Luigi Cadorna, Commander-in-Chief
General Brusatti
General Pecori-Giraldi
Duke of Aosta
Admiral Patris

Austrian Forces, 750,000
General Boroevic
General von Hofer
General Koevess
General von Rohr
General Dankl
Archduke Eugene
Archduke Charles

At midnight on May 23, 1915, the Armies of Italy were set in motion northward to seize and close the gateways of the Austro-Italian frontier, which extended 450 miles from the Swiss border to the Adriatic Sea, a stretch half again as long as that covered by the Allied front in Belgium and France. Throughout its greater part, this frontier was formed by the natural barrier of the Alps, whose myriad peaks tower miles in air, overlooking the sunny plains of Venice and Lombardy. Along this mountain barrier the Austrians had constructed a system of defensive works, which seemingly defied frontal attacks.

From foothills to summits, these awesome Alpine slopes were seamed with parallel lines of trenches, protected by wire entanglements and with permanent gun emplacements and turrets fixed at intervals. To assault this mountain fortress in mass was deemed impracticable; only by attacking each fortified peak in separate operations and by relatively small bodies of troops might success be attained. Yet it was necessary to cover the whole extent of the frontier with Italian troops, lest the Austrians should pour down into the Northern plains of Italy. The actual goal of the Italian Armies, however, was not the Trentino and Tyrolean regions in the North, but Trieste in the East.

The way to Trieste, through a 25-mile passage along the Isonzo River, between Cividale and the Adriatic Sea, was unopposed by the Alps. Instead, two parallel railways, some ten miles apart, led eastward from the Isonzo front, one from Gorizia following the course of a branch of the Isonzo River; the other from Monfalcone by way of Carso, following the seacoast direct to Trieste. The central pivot of the...

In many ways the Battles of the Isonzo mirrored those on the Western Front, albeit on a smaller scale. As with the ongoing battle raging in France and Flanders the lines across the Isonzo were defined by the onset of trench warfare. For a single-article background to the Isonzo battles click here.

Despite having been part of the pre-war Triple Alliance with Austro-Hungary and Germany, in 1914 Italy had remained neutral. Over the next few months both sides attempted to convince the Italians to join them. The British and French had a big advantage in this effort – the Italians had claims on two parts of the Austro-Hungarian Empire. At the end of the Italian Wars of Independence two major Italian speaking areas had remained within the Empire – the Trentino, north of Lake Garda, and the Littoral, the lower Isonzo valley and the area around Trieste. The Allies were able to promise that Italy would receive these areas at the end of the war; and so on 23 May 1915 Italy declared war on the Allied side.

The Italians had one major problem in 1915. Their 400 mile long border with the Austro-Hungarian Empire ran through the Alps. In some places the mountains were so rugged that no offensive could even be contemplated. The only real gap in the mountains led along the Adriatic coast to Trieste, but that was a dead end, surround by more mountains. If the Italians were to launch an effective assault on the Austrians, then it would either have to be on the Trentino, or towards the Isonzo valley.