The 60-mile-long valley of the Isonzo [Soca] River running from the Julian Alps south to the Adriatic Sea bisected the only practical area for offensive operations by the Italian Army during the Great War. Throughout most of the rest of the mountainous 400-mile length of the S-shaped Italian Front the dominating positions almost everywhere were in the hands of the Austro-Hungarian forces. A Delimitation Commission following the War of 1866 had intentionally given Austria a highly defensible frontier. But by attacking across the coastal plain east of the lower end of the Isonzo River, they could, so judged Supreme Commander Luigi Cadorna, feasibly acquire a series of territorial objectives from Gorizia to Trieste down to the Dalmatian coast. Secondarily, farther to the north they believed they could leapfrog the mountains bracketing both sides of the river and strike a strategic blow against their opponent's rear. Two offensives were mounted in the summer of 1915, but heavy casualties and ammunition shortages doomed them. In the fall Cardona mounted new attacks.
18 October–3 November 1915
The brutality of the fighting escalated even further with the Third and Fourth Battles of the Isonzo. General Cadorna was now looking for the "big breakthrough," but continuing his neglect of the principle of mass he committed forces the length of the front once again. He did try to narrow his areas of attack in each region and raised his artillery count to 1,200 guns, but, once again, he spread his forces too thin for what he hoped of them.
|Trenches on Mte. Sei Busi, Carso Plateau|
This Was One of the Worst Killing Grounds for the Italian Army in the War
Efforts to reduce his enemy's bridgeheads at Plezzo and Tolmino were ordered leading to innumerable, but indecisive, actions in those areas. Other attacks were mounted against Plava on the south edge of the Bainsizza Plateau. Also, the Carso heated up once more as St. Michele became the keystone to a flanking move on Gorizia. Nearby Monte Sei Busi, defended ferociously by the Austrian 106th Division, was the scene of at least four major assaults. Attacking on narrower fronts, though, meant the Austrians could focus more of their firepower over smaller sections. Borojevic also started receiving additional divisions from the Eastern and Balkan Fronts and staged some ferocious counterattacks against the Italians around St. Michele. In early November Italy's supreme commander ordered a temporary halt to reevaluate the situation.
|Crossing a Foot Bridge on the Isonzo|
Fourth Battle of the Isonzo
10 November–2 December 1915
The Fourth Battle of the Isonzo was really a second phase to the Third Battle. Fighting was more, but not exclusively, concentrated around Gorizia and on the Carso. In the first case, the Second Army mounted its greatest assault capturing Oslavia, but with not quite enough momentum left to gain Gorizia. South down to the Adriatic, the Third Army simply accumulated more and more casualties. Typical, was the fighting around Monte Sei Busi where five more assaults were mounted by the Italian Army.
|Looking South Down the Isonzo; Tolmino on Left|
The Austrians Occupied the High Ground on Both Sides for the Entire War
This Was One of Two Breakthrough Points During the Battle of Caporetto
Toward the end of the Fourth Battle, action heated up again up and down the Isonzo Front from Tolmino down to Monte San Michele reaching a peak at the end of November. From the first of December to mid-month action shifted from major frontal assaults to small local actions. Halting for the winter, the troops on the Carso would learn they had achieved little since June except exchanging the pounding sun of the summer for a crushing northern winter wind off of the Alps known as the Bora.
|Austro-Hungarian Defenders on the Carso|
Political turmoil and the urgency to gain something for all the sacrifices of Italy and ethnic instabilities in the Austro-Hungarian Empire meant that in 1916 Italy needed to continue attacking and Austria-Hungary needed to continue defending. The war of attrition would continue growing with both sides blind to the inevitable consequences.