Isonzo Front and its 12 battles

Ljubljana, 10 May - The Isonzo Front, the biggest mountain campaign in human history and the biggest military confrontation on Slovenian territory, started on 23 May 1915 when Italy declared war on the Austro-Hungarian Empire. The campaign comprised 12 bloody battles and ended in October 1917.

Bovec
Bosnian soldiers fighting for Austria-Hungary in WWI on Mt Rombon.
Photo: Archive of the Isonzo Front 1915-1917 Association

Kras plateau
Poison gas being deployed in WWI.
Photo: Archive of the Isonzo Front 1915-1917 Association

Soldiers wearing gas masks in WWI.
Photo: Archive of the Isonzo Front 1915-1917 Association

Italian prisoners of war, captured on the Isonzo Front in WWI.
Photo: Archive of the Isonzo Front 1915-1917 Association

Kobarid
The view of nearby mountains from the Kolovrat plateau, which was the scene of bitter fighting during WWI - left to right: Krn (2244 m), Batognica (2164 m), Vrh nad Peski (2176 m), Srednji vrh (2032 m), Maselnik (1906 m), Veliki Stador (1903 m) and Mrzli vrh (1359 m).
Photo: Anže Malovrh/STA

One of the main theatres of WWI, the Isonzo Front spanned some 90 kilometres along the Soča river (Isonzo in Italian) and resulted in over one million killed, wounded or missing soldiers. All the battles except the last one were initiated by the Italian side.

23 June - 7 July 1915 - The 1st Battle of the Isonzo: The Italian army attempted to take the western rim of the Kras plateau, south of Gorizia, attacking at Doberdo, but only winning the foot of the plateau with great difficulty. Although the Italians outnumbered the Austro-Hungarian army two-to-one, the offensive reached none of its targets and cost Italy 1,916 dead, 11,495 wounded and 1,536 missing soldiers. The losses of Austria-Hungary were almost as high, with 1,224 soldiers killed, 7,576 wounded and 1,150 missing.

18 July - 3 August 1915 - The 2nd Battle of the Isonzo: In their next thrust, the Italian army pushed towards the Austrian bridgehead south of Gorizia, briefly taking Mount San Michele, but losing it in a counter-attack by a group of elite regiments. On the northern part of the front, however, the Italians managed to capture Mount Batognica above Kobarid (Caporetto), pushing the Austro-Hungarians to the second defence line. Both sides suffered heavy losses, with 6,287 soldiers killed on the Italian and 7,702 on the Austro-Hungarian side.

18 October - 4 November 1915 - The 3rd Battle of the Isonzo: The Italians managed to establish a bridgehead at Plave north of Gorizia and capture Mount San Michele in an attempt to outflank the forces defending the town from both sides, but all other assaults were unsuccessful despite heavy casualties on both sides. The attackers lost around 68,000 soldiers, of whom 10,733 were killed, and the defenders lost around 42,000, of whom 8,228 were killed.

10 November - 2 December 1915 - The 4th Battle of the Isonzo: Although the next push was distributed along the entire front, most of the fighting took place around Gorizia and in the Kras plateau. The Italian advance was insignificant. They took a hilly area overlooking Gorizia across the Soča river, but were unable to reach the town despite five attacks. Around 7,500 Italian and 3,700 Austro-Hungarian soldiers died in this battle, while total losses amounted to almost 49,000 killed, wounded or missing soldiers on the Italian and over 25,000 on the Austro-Hungarian side.

11-16 March 1916 - The 5th Battle of the Isonzo: The first offensive after the winter consisted mostly of unsuccessful local attacks, mainly at Gorizia and Tolmin. The offensive was meant as a distraction for Central Powers from the other fronts and was among the least bloody battles, with each side losing around 2,000 soldiers, including those wounded or captured.

4-16 August 1916 - The 6th Battle of the Isonzo: This was the most successful of the eleven attacks launched by the Italians. With Austro-Hungarian lines depleted to reinforce an attack on Trentino, the Italians managed to capture a demolished Gorizia and pushed the Austro-Hungarians to the second defence line. Despite heavy casualties, the victory boosted Italian morale and the country officially declared war on Germany on 28 August. Over 6,000 Italian and over 4,000 Austro-Hungarian soldiers were killed, and around 33,000 were wounded on the attacking and 20,000 on the defending side.

13-17 September 1916 - The 7th Battle of the Isonzo: After taking Gorizia, the Italian offensive focused on the western part of the Kras plateau in an attempt to push towards the port city of Trieste. Starting with this battle, the Italians shifted their tactics from diversionary to focused single-point attacks. They pushed the defenders from Miren Castle and proceeded further towards the south. Despite a short duration, losses were high, with around 2,500 killed on each side.

9-12 October 1916 - The 8th Battle of the Isonzo: The Italian army continued to push towards the east but with little success. This time, the casualties on the Austro-Hungarian side were higher. In only three days of fighting, Italy lost over 20,000 soldiers, of whom some 3,000 were killed, while Austria-Hungary lost over 30,000 soldiers, of whom around 4,000 were killed.

31 October - 4 November 1916 - The 9th Battle of the Isonzo: Italian airplanes bombed Sežana, Dutovlje, and Miramar Castle near Trieste. Although the Italians almost won the war of attrition and almost entirely destroyed the defences, they failed to make a significant breakthrough and their own losses wore them out so much that they chose to fortify the positions they managed to take, thus allowing the Austro-Hungarian side to recuperate during the winter. Around 8,000 Italian and some 2,500 Austro-Hungarian soldiers died in this battle.

12 May - 5 June 1917 - The 10th Battle of the Isonzo: The next two offensives were by far the bloodiest in the two and a half years of the Isonzo Front. The Italians tried to push through to Trieste and into the Vipava Valley, but their attacks were mostly unsuccessful. Italy lost almost 159,000 soldiers, of whom 36,000 were killed. The defending side lost some 76,000 soldiers, of whom over 7,000 were killed.

17 August - 12 September 1917 - The 11th Battle of the Isonzo: The last Italian-initiated offensive was even bloodier than the previous one. The most bitter fighting took place on the Škabrijel hill north-east of Gorizia, which the Italians won and lost nine times during the course of this battle. Had they managed to hold this strategic position, they would have broken through the defence lines and had an open path into the inland territory of the empire. In their effort, the Italians lost 166,000 soldiers, of whom 40,000 were killed, while Austria-Hungary lost 85,000 soldiers, of whom 10,000 were killed.

24-28 October 1917 - The 12th Battle of the Isonzo: The only offensive launched by Austria-Hungary with the support of its German allies is referred to as the "Miracle of Kobarid", while the Italian name for the town, Caporetto, is still used in Italian as a synonym for a big fiasco. Using poison gas, the joint Austro-Hungarian and German forces broke through the front line at Kobarid, retook all the positions along the Soča and in the days that followed, pushed the Italians all the way to the Piave river, some 30 kilometres north of Venice. Around 10,000 soldiers were killed on the side of the Central Powers and between 10,000 and 13,000 on the Italian side. As many as 265,000 Italians were captured. The Isonzo Front was over after 885 days.

3 November 1918: The Austro-Hungarian high command signed an armistice with Italy, and on 5 November the Italians marched into the city of Trieste.

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© STA, 2017