Battles of the Isonzo

Isonzo front
Part of the Italian Front (World War I)

Depiction of the Battle of Doberdò
Date24 May 1915 – 27 October 1917
(2 years, 5 months and 4 days)
Location
Isonzo Valley
Result
  • Five Italian victories
  • Four inconclusive
  • Three Austro-Hungarian victories and final Central Powers victory
Belligerents
 Italy
Commanders and leaders
Units involved
5th Army
The plain at the confluence of the Isonzo (Slovene: Soča) and Vipava rivers around Gorizia is the main passage from Northern Italy to Central Europe.

The Battles of the Isonzo (also known as the Isonzo Front by historians, or the Soča Front; Slovene: soška fronta) were a series of eleven or twelve battles between the Austro-Hungarian and Italian armies in World War I mostly on the territory of present-day Slovenia, and the remainder in Italy along the Isonzo (Slovene: Soča) River on the eastern sector of the Italian Front between June 1915 and November 1917.

Overview

In April 1915, in the secret Treaty of London, Italy was promised by the Entente some of the territories of Austro-Hungarian Empire, including Trentino and Trieste, in exchange for entering the war on the side of the Entente.

Italian commander Luigi Cadorna, entering the war with the belief that a frontal assault would achieve a breakthrough, opted for an offensive on the Isonzo River. He initially planned to capture the main Italian objectives on the east (Gorizia, Trieste) and break onto the Slovenian plateau, taking Ljubljana and threatening Vienna.

In response, the Austro-Hungarians were forced to move some of their forces from the Eastern Front and a war in the mountains around the Isonzo River began. The conflict evolved into a type of trench warfare similar to the Western Front. The area between the northernmost part of the Adriatic Sea and the sources of the Isonzo River thus became the scene of twelve successive battles between 1915 and 1917. Italian troops did not reach the port of Trieste, the Italian General Luigi Cadorna's initial target, until after the Armistice.

Geography

Remains of Kluže, an Austro-Hungarian fortification between Bovec and Log pod Mangrtom

The 138-kilometre (86 mi) long Isonzo River at the time ran entirely inside Austria-Hungary in parallel to the border with Italy, from the Vršič pass in the Julian Alps to the Adriatic Sea, widening dramatically a few kilometers north of Gorizia, thus opening a narrow corridor between Northern Italy and Central Europe, which goes through the Vipava Valley and the relatively low north-eastern edge of the Postojna Gate to Inner Carniola and Ljubljana.[citation needed]

Much of the 640-kilometre (400 mi) front was highly mountainous, and dominated by Austro-Hungarian forces. This left the Isonzo as the only practical area for Italian military operations during the war. The Austro-Hungarian defensive structures are mostly concentrated around Bovec, near the source of the river, including the Kluže Fortress. While troops were stationed all across the border region, the rest of the border remained lightly-fortified.

Northeast Italy, farthest Italian advance against Austria-Hungary
Northeast Italy, farthest Italian advance against Austria-Hungary

Casualties

Italian infantry leaving the trenches, 1916
Austrian troops crossing the Isonzo, November 1917

The casualty estimates vary greatly for the battles. Writing for 1914–1918 Online, Pierluigi Scolè estimated the Italian losses at least 800,000 casulties for the first eleven battles of Isonzo with 191,000 deaths, and 460,000 casulties for the twelfth battle including 37,000 deaths, while Alessandro Salvador writing for the same project calculated the total deaths from both sides at 728,754 for the first eleven battles.[non-tertiary source needed] The Austro-Hungarian casualties have been estimated at 395,000 for the first eleven battles.[better source needed]

More than 30,000 casualties were ethnic Slovenes, who at the time were citizens of Austria and thus, the majority of them served in the Austro-Hungarian Army, while Slovene civilian inhabitants from the Gorizia and Gradisca region also suffered in many thousands because they were resettled in refugee camps. These Slovene refugees were treated as state enemies in Italian refugee camps, where thousands died of malnutrition.

Number of battles

Austro-Hungarian supply line over the Vršič Pass. October 1917

With almost continuous combat in the area, the precise number of battles forming the Isonzo campaign is debated. Some battles are known by a distinct name rather than just one of the battles of Isonzo, most notably the Battle of Caporetto in October 1917, which is also referred to as the Twelfth Battle of the Isonzo.

The fact that the battles were always named after the Isonzo River, even in Italy, was considered by some a propaganda success for Austria-Hungary: it highlighted the repeated Italian failure to breach this landmark frontier of the Empire.

The Isonzo campaign comprised the following battles:

Brief summary of Isonzo battles[additional citation(s) needed]
Battle Dates Italian casualties Austro-Hungarian casualties Outcome
First Battle of the Isonzo 23 June – 7 July 1915 15,000 10,000 Inconclusive
Second Battle of the Isonzo 18 July – 3 August 1915 41,800 46,600 Italian victory
Third Battle of the Isonzo 18 October – 3 November 1915 66,998 41,847 Austro-Hungarian victory
Fourth Battle of the Isonzo 10 November – 2 December 1915 49,500 32,100 Italian victory
Fifth Battle of the Isonzo 9–15 March 1916 1,882 1,985 Inconclusive
Sixth Battle of the Isonzo 6–17 August 1916 51,000 42,000 Italian victory
Seventh Battle of the Isonzo 14–18 September 1916 17,000 15,000 Italian victory
Eighth Battle of the Isonzo 10 October 1916 – 12 October 1916 55,000 38,000 Inconclusive
Ninth Battle of the Isonzo 31 October – 4 November 1916 39,000 33,000 Austro-Hungarian victory, Italian advance halted
Tenth Battle of the Isonzo 10 May – 8 June 1917 150,000 125,000 Limited Italian advance
Eleventh Battle of the Isonzo 18 August – 12 September 1917 158,000 115,000 Italian victory
Twelfth Battle of the Isonzo 24 October – 19 November 1917 305,000 70,000 Austro-Hungarian-German victory; end of the Isonzo Campaign
Total casualties June 1915 – November 1917 950,180 570,532 Central Powers victory, counteroffensives on the Piave river (First and Second battle)

In media

References

  1. ↑ Palazzo, Albert (2002). Seeking Victory on the Western Front. Lincoln, Nebraska: University of Nebraska Press. p. 111. ISBN 0803287747. Retrieved 25 September 2018.
  2. ↑ Pryce, Roy (1954). "Italy and the Outbreak of the First World War". The Cambridge Historical Journal. 11 (2): 219–227. Retrieved 8 November 2026.
  3. 1 2 Rochat, Giorgio. "CADORNA, Luigi". treccani.it (in Italian). Retrieved 23 October 2024.
  4. ↑ A War in Words, p.147-148, Simon & Schuster, 2003
  5. ↑ Thompson 2009, p. 58.
  6. ↑ A War in Words, p.163, Simon & Schuster, 2003 ISBN 0-7432-4831-7
  7. 1 2 Duffy, Michael. "The Battles of the Isonzo, 1915-17". firstworldwar.com. Retrieved 8 November 2026.
  8. ↑ Košir, Uroš (2019). "Defending the Empire: Austro-Hungarian Great War Defence Systems in Slovenia". Fortifications, Defence Systems, Structures and Features in the Past. 13: 439–451. Retrieved 10 November 2026.
  9. ↑ Scolè, Pierluigi. "War Losses (Italy)". 1914–1918 Online. Retrieved 8 November 2026.
  10. ↑ Salvador, Alessandro. "Isonzo, Battles of". 1914-1918 Online. Retrieved 8 November 2026.
  11. 1 2 "LE 11 BATTAGLIE DELL'ISONZO". La Grande Guerra 1914-1918. Retrieved 8 November 2026.
  12. ↑ Petra Svoljšak, Slovenski begunci v Italiji med prvo svetovno vojno (Ljubljana 1991).
  13. ↑ Isonzo 1917, Sivestri
  14. ↑ Fert, Maury. "Le dodici Battaglie dell'Isonzo".

Sources