Battles of the Isonzo

For the Ostrogoth invasion of Italy, see Battle of Isonzo (489).

Isonzo front
Part of Italian Front (World War I)
Depiction of the Battle of Doberdò.
Date 23 May 1915 – 27 October 1917 (2 years, 5 months and 4 days) Location Isonzo River valley Result Five Italian victories Three inconclusive Three Austro-Hungarian victories and final Central Powers victory
Belligerents
Kingdom of Italy	Austria-Hungary German Empire
Commanders and leaders
Luigi Cadorna Armando Diaz	Rudolf von Steinstätten Svetozar Borojević
Units involved
2nd Army 3rd Army	5th Army
Casualties and losses
645,000 (pre-Caporetto)	450,000 (pre-Caporetto)

The plain at the confluence of the Soča and Vipava rivers around Gorizia is the main passage from Northern Italy to Central Europe.

The Battles of the Isonzo (known as the Isonzo Front by historians, Slovene: soška fronta) were a series of 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 River on the eastern sector of the Italian Front between June 1915 and November 1917.

Italian military plans

In April 1915, in the secret Treaty of London, Italy was promised by the Allies some of the territories of Austro-Hungarian Empire which were mainly inhabited by ethnic Slovenes and Austrian Germans.

Italian commander Luigi Cadorna, a staunch proponent of the frontal assault who claimed the Western Front proved the ineffectiveness of machine guns, initially planned breaking onto the Slovenian plateau, taking Ljubljana and threatening Vienna. 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.. It was overall a massive failure for the Italian army, as they failed to achieve their original objectives and suffered heavy casualties in the process, highlighting ineffective leadership that would plague Italy into the next world war.

As a result, 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.

Geography

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

The sixty-mile long Soča River at the time ran entirely inside Austria-Hungary in parallel to the border with Italy, from the Vršič and Predil passes 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 Karst Plateau to Inner Carniola and Ljubljana. The corridor is also known as the "Ljubljana Gate".

By the autumn of 1915 one mile had been won by Italian troops, and by October 1917 a few Austro-Hungarian mountains and some square miles of land had changed hands several times. Italian troops did not reach the port of Trieste, the Italian General Luigi Cadorna's initial target, until after the Armistice.

Primary sector for Italian operations

Italian soldiers during the Second Battle of the Isonzo, 1915

With the rest of the mountainous 400-mile (640 km) length of the Front being almost everywhere dominated by Austro-Hungarian forces, the Soča (Isonzo) was the only practical area for Italian military operations during the war. The Austro-Hungarians had fortified the mountains ahead of the Italians' entry into the war on 23 May 1915.

Italian Chief of Staff Luigi Cadorna judged that Italian gains (from Gorizia to Trieste) were most feasible at the coastal plain east of the lower end of the Soča (Isonzo). However he also believed that the Italian army could strike further north and bypass the mountains on either side of the river so as to come at the Austro-Hungarian forces from the rear.

Cadorna had not expected operations in the Isonzo sector to be easy. He was well aware that the river was prone to flooding—and indeed there were record rainfalls during 1914–1918.

Further, when attacking further north the Italian army was faced with something of a dilemma: in order to cross the Isonzo safely it needed to neutralise the Austro-Hungarian defenders on the mountains above, yet to neutralise these forces the Italian forces needed first to cross the river—an obstacle that the Italians never succeeded in overcoming.

In the south (along the coastal zone) geographic peculiarities, including an array of ridges and valleys, also gave an advantage to the Austro-Hungarian defenders.

Northeast Italy, farthest Italian advance against Austria-Hungary

Casualties

Italian infantry leaving the trenches, 1916

Austrian troops crossing the Isonzo, November 1917

Despite the huge effort and resources poured into the continuing Isonzo struggle, the results were invariably disappointing and without real tactical merit, particularly given the geographical difficulties that were inherent in the campaign.

Cumulative casualties of the numerous battles of the Isonzo were enormous. Half of the entire Italian war death total—some 300,000 of 600,000—were suffered along the Soča (Isonzo). Austro-Hungarian losses, while by no means as numerous, were nevertheless high at around 200,000 (of an overall total of around 1.2 million casualties).

More than 30,000 casualties were ethnic Slovenes, the majority of them being drafted into 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 where 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 debatable. Some historians have assigned distinct names to a couple of the Isonzo struggles, most notably at Kobarid (Caporetto or Karfreit) in October 1917, which would otherwise form 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:

• First Battle of the Isonzo – 23 June – 7 July 1915
• Second Battle of the Isonzo – 18 July – 3 August 1915
• Third Battle of the Isonzo – 18 October – 3 November 1915
• Fourth Battle of the Isonzo – 10 November – 2 December 1915
• Fifth Battle of the Isonzo – 9–17 March 1916
• Sixth Battle of the Isonzo – 6–17 August 1916
• Seventh Battle of the Isonzo – 14–17 September 1916
• Eighth Battle of the Isonzo – 10–12 October 1916
• Ninth Battle of the Isonzo – 1–4 November 1916
• Tenth Battle of the Isonzo – 12 May – 8 June 1917
• Eleventh Battle of the Isonzo – 19 August – 12 September 1917
• Twelfth Battle of the Isonzo – 24 October – 7 November 1917, also known as the Battle of Caporetto

Brief summary of Isonzo battles

Battle	Dates	Italian casualties	Austro-Hungarian casualties	Outcome
First Battle of the Isonzo	23 June – 7 July 1915	15,000	10,000	Limited Italian advance
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	Austro-Hungarian 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	75,000	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	Decisive Austro-Hungarian victory; end of the Isonzo Campaign
Total casualties	June 1915 – November 1917	950,180	520,532	Central Powers victory, counteroffensives on the Piave river (First and Second battle)

In media

• Ernest Hemingway's A Farewell to Arms is partly during the events along this front.
• Italian poet Giuseppe Ungaretti's autobiographical poem, "I Fiumi", was written about the Isonzo whilst he was stationed on the front.
• Mark Helprin's A Soldier of the Great War refers to parts of the Isonzo campaign.
• The twelfth battle is the subject of the novel Caporetto by the Swedish author F. J. Nordstedt, Stockholm 1972.
• The Isonzo Front is the theme for the video game Isonzo by Blackmill Games.
• Emilio Lussu's A Soldier on the Southern Front is an account of the Izonzo campaign from the Italian side.

Sources

• Thompson, Mark (2009). The White War: Life and Death on the Italian Front, 1915-1919. Faber & Faber. ISBN 978-0571223336.

External links

• FirstWorldWar.Com The Battles of the Isonzo, 1915–17
• FirstWorldWar.Com Battlefield Maps: Italian Front
• 11 battles at the Isonzo
• The Walks of Peace in the Soča Region Foundation. The Foundation preserves, restores and presents the historical and cultural heritage of the First World War in the area of the Isonzo Front for the study, tourist and educational purposes.
• The Kobarid Museum (in English)
• Društvo Soška Fronta (in Slovene)
• Pro Hereditate – extensive site (in English, Italian, and Slovene)
• Interactive map with the extensive documentation with 360° Surround photography virtual tours
• Rapporto Ufficiale. Published 1929–1974. 10 books - free access to the full texts (Italian))