Battle of Caporetto, 1917: the breakthrough on the Isonzo

The shells began to fall at two in the morning, many of them gas. By daylight the attackers were moving down the valley floors below the Italian positions on the heights, and by nightfall some had advanced 25 kilometers. Within two weeks the Italian army, which had attacked on this river eleven times in two and a half years, had lost everything it had won there and was fighting for Venice.²

Caporetto is the Italian name of Kobarid, a small town on the Soča river, the Isonzo of Italian maps, in today's Slovenia; the Germans called it Karfreit. The battle named after it is also called the Twelfth Battle of the Isonzo.³

Background: eleven battles on the Isonzo

Italy entered World War I against Austria-Hungary in May 1915. Its commander in chief, General Luigi Cadorna, held the Trentino on the defensive and attacked along the Isonzo, eleven times, at a heavy cost and for little ground: less than seven miles, about a third of the way to Trieste.⁴

The Eleventh Battle, in August and September 1917, took a large part of the Bainsizza plateau north of Gorizia, and it strained the Austro-Hungarian army almost to breaking point. Vienna asked Berlin for help. The Austro-Hungarian command had concluded that it could not withstand another Italian offensive, whether it came in late autumn or in the spring. The German high command at first regarded the Italian front as secondary, but it changed its mind for fear of an Austro-Hungarian collapse; Ludendorff, as Britannica quotes him, decided on the attack on Italy "in order to prevent the collapse of Austria-Hungary."⁵

Armies and commanders

The attackers. Germany sent seven divisions to the upper Isonzo. With Austro-Hungarian divisions they formed a new Fourteenth Army under the German general Otto von Below. Britannica counts seven German and eight Austro-Hungarian divisions in it; the 1914-1918-online encyclopedia, six German and nine Austro-Hungarian. The army was to break through the mountain barrier between Bovec and Tolmin, with Caporetto in the middle of the line.⁶

The plan rested on surprise. The arrival of the new army was concealed, and Britannica writes that the concentration went undiscovered, helped by the Italians' limited air reconnaissance. History.com, on the other hand, says that Cadorna learned of the Austro-German movements from the air. Either way, the Italians were caught unprepared when the attack came.⁷

Among the German junior officers was a young lieutenant, Erwin Rommel, who had already fought in France and Romania. Rickard notes that on the Italian front he earned the Pour le Mérite, one of Germany's top awards for valor, in a night operation.⁸

The defenders. The sector was held by the Italian Second Army of General Luigi Capello, who had led the attack on the Bainsizza in August. Cadorna ordered his armies onto the defensive in September, but his directives were vague and were not enforced, and Capello, who still wanted to attack, did not cooperate wholeheartedly. The World of the Habsburgs notes that adequate defensive positions were dispensed with and the guns were left on the front line.⁹

The battle in phases

24 October: the breakthrough. At two o'clock in the morning the bombardment began: hours of gas shelling, then a short and violent fire on the Italian positions, aimed above all at their communications. Then the infantry went in, not in dense waves but in small, independent groups that slipped past strongpoints and into the rear, using grenades and flamethrowers. Gas shells were aimed in particular at the Italian batteries dug into the mountainsides. The attackers broke through at Bovec and at Tolmin, and some units advanced 25 kilometers on the first day.¹⁰

From the mountains to the plain. Below's divisions pushed down the western slopes of the mountains, threatening the Italian armies to the north and south. Udine, the former Italian headquarters, fell on 28 October. The 1914-1918-online encyclopedia has the attackers almost at the Tagliamento by 29 October; Britannica has the leading units reaching it on 31 October. The defeat was so complete that the attackers themselves were surprised and lacked the forces to exploit it fully. With his center broken, Cadorna saved his wings by a headlong retreat: by the time the attackers reached the Tagliamento, the Italian Third Army from the lower Isonzo had crossed it or was about to.¹¹

The retreat. Cadorna ordered his armies back, first to the Tagliamento and then to the Piave. By 9 November, Britannica writes, all the Italian forces still under command were behind the Piave, some 70 miles from the Isonzo front; History.com gives about 60 miles. The new line covered Venice.¹²

Turning point: a front without depth

What turned a local breach into a catastrophe was the shape of the Italian defense. Jones points out that the Italians had failed to build a defense in depth, so that within hours the break-in at Bovec became a breakthrough; the 1914-1918-online encyclopedia stresses the cut communications that left troops without orders, and the lack of trained reserves.¹³

The line that finally held was on the Piave. On 9 November Cadorna was removed and General Armando Diaz took his place. British and French troops began to arrive to support the Italian army, a British and a French corps by Britannica's count, six French and five British divisions by that of the 1914-1918-online encyclopedia.¹⁴

On the Piave the Italian army recovered. Britannica writes that the invaders had outrun their transport and that the Italians, braced by the emergency, held the river against direct assaults; Rickard, that Diaz re-established a stable front and set about restoring the confidence of an army that had nearly been shattered.¹⁵

Aftermath: how many men did Italy lose?

The losses are disputed, and the argument is mostly about prisoners and men who left the ranks, not the dead. The 1914-1918-online encyclopedia counts 11,000 dead, 29,000 wounded, 300,000 prisoners and about 300,000 more scattered. History.com gives about 40,000 killed or wounded, 280,000 captured and 350,000 deserters; the World of the Habsburgs, the same 40,000 and 280,000 but only tens of thousands of deserters. Britannica counts 250,000 prisoners and nearly twice as many other casualties. The 1914-1918-online encyclopedia puts the attackers' losses at about 50,000 killed or wounded.¹⁶

Even the end date varies: Rickard ends the battle on 12 November, when the Piave line held, while Britannica follows the fighting until 19 December, when the snows ended the attacks in the mountains.¹⁷

In Italy the defeat brought anger and fear into the open. Violent anti-war protests reached a peak, and in Turin and Milan the army put down revolts and demonstrations with shootings and death sentences. Yet the defeat also hardened national resistance: Italy now fought a defensive war, with more men mobilized and allied help, under a new government and a new command.¹⁸

For the Central Powers the victory proved ephemeral. Britannica judges that the attack lacked a strategic context, and the World of the Habsburgs that it brought more danger than gain to the monarchy, which now had to feed several hundred thousand prisoners while its own cities ran short of food and fuel. In June 1918 the Austro-Hungarian offensive on the Piave failed.¹⁹ › How World War One Ended

Legacy and memory

Caporetto remains the worst defeat the Italian army has ever suffered, and the Italians themselves came to speak of the catastrophe of Caporetto.²⁰

The retreat also entered literature. In Ernest Hemingway's novel A Farewell to Arms, published in 1929, the American ambulance officer Frederic Henry deserts during the Italian retreat after Caporetto, narrowly escaping execution by the military police. Hemingway himself only reached Italy as a Red Cross ambulance volunteer in 1918, months after the retreat he described.²¹

Visiting today

Kobarid keeps the memory of the front. On Gradič hill above the town stands the Italian charnel house, built around the seventeenth-century church of St Anthony and opened by Benito Mussolini in 1938; the remains of 7,014 known and unknown Italian soldiers were brought there from the military cemeteries of the area.²²

The Kobarid Museum, devoted to the Isonzo front, won the Council of Europe Museum Prize in 1993. It also runs an outdoor museum on the Kolovrat ridge, where Italian third-line trenches, gun positions and observation posts have been restored, with a view over the whole Soča valley. Both the charnel house and the Kolovrat museum lie on the Walk of Peace, a trail of some 320 kilometers that follows the old Isonzo front from the Alps to the Adriatic.²³