Fortifications of Austria-Hungary during the WWI



A 305mm Skoda Emma howitzer.



To secure their Balkan territories, the Austrians built a variety of fortifications in the area. Some of the most unusual forts were part of the fortress defences of the ports of Pola and Cattaro where the construction programme began in the 1880s. Pola was encircled with an inner and outer ring of forts. By 1900, the outer ring consisted of five forts converted from earlier field works and the inner ring included several older ones. Some of the old forts and most of the new ones mounted batteries of eight to ten 150mm Kanone M-61 and 90mm Kanone M-75 on a lower rampart. In 1914, battery positions and some strongpoints were added to the outer ring. In the 1880s, the coastal defences of Pola included twelve batteries and a few forts mounting mostly 150mm, 210mm, 240mm, and 280mm Krupp guns as well as a few 210mm M-80 coast mortars. In 1914, some of the positions were improved and Fort Gomila, near Pola, received two 420mm howitzer turrets. These were the first of the 420mm weapons produced at the Skoda Works. Several forts and strongpoints formed Cattaro’s landward defences by 1914. Both ports had torpedo batteries for their coastal defences.

Several Panzerwerke were built along the border with Serbia and Montenegro, some of which were not completed until 1916. Most mounted two 100mm howitzer turrets. At Visegrad, Sperre Avtoac had four turrets, as did another werk at Bileca. The three werke at Trebinje and one at Krisovije each mounted two turrets. There were two other werke at Krisovije, including one with four turrets and another with the standard two 100mm howitzer turrets and two 150mm mortar turrets. Some of these positions were the most recently built in the empire.

By 1914, every front of the empire sported an array of forts of various sizes, shapes, and armoured components. Thus, it would be impossible to describe a typical Austro-Hungarian fort of the empire since they varied within fortresses and styles were very different in various parts of the empire.

It seems curious that the Austrians lavished so much attention on fortifying the Italian frontier in the twentieth century when the main threat appeared to be from Russia. Italy was after all a member of the Triple Alliance and supposedly an ally. However, the Germans did not seem fully convinced the Italians would honour their agreement. The Austrians also knew that the Italians still coveted the Trento and Trieste regions.

When war finally broke out, the enemy turned out to be Serbia. The Austro-Hungarian defences on the Balkan Front were adequate and relatively modern. The Galician Front continued to be important, especially after the Germans left minimal forces in the East to concentrate their great offensive in the West. Rumania’s status was questionable, increasing the importance of Austria’s position in Transylvania. Since Italy, which was still an ally in theory, had not entered the war, low-grade reservists were left to watch the Italian Front. When Italy eventually entered the war in 1915, it abandoned the Triple Alliance and joined the Allies.

The war began as a result of the assassination of Archduke Franz Ferdinand in Sarajevo and Serbia’s subsequent refusal to accept all of Austria’s demands. The 6th Austrian Army stood on watch along the Montenegrin border while the 5th Army invaded Serbia by crossing the Drina River. Since the Austro-Hungarian Empire was just across the river, Belgrade could not have a fortress ring to protect it from heavy artillery. However, the Austrians chose another route into terrain that favoured the defender for their August offensive into Serbian territory. As a result, their incursion ended in ignominious defeat as their troops retreated across the river forming the border at the end of the month. In September, a Serbian army crossed the Danube giving Belgrade some breathing space in case the Austrians decided to assault the city. The Austrians launched a second incursion across the Drina River but fared little better than the first time. Trench fighting continued on that front until December 1914 when the Serbs, because of attrition, finally pulled back and abandoned their capital. The Serbs went back on the offensive in December and retook their capital. Serbia did not fall until September 1915 after Bulgaria entered the war opening a new front against it. However, the odds were stacked against Serbia despite the early failures of the Austro-Hungarian Army. Its Montenegrin ally was only able to attack the empire in places where the terrain was not greatly different and favoured defence rather than offence. In addition, the Austrians had fortifications.

In late August, Paul von Hindenburg’s German Army in East Prussia handed the Russians a major defeat at Tannenberg, well before they reached the German fortifications of Königsberg. Before this, General Franz Conrad von Hötzendorf, who still had not had to contend with the fiasco in Serbia, had ordered four Austrian armies in Galicia to advance toward Lublin to cut Russian lines of communication south of the Pripet Marshes and to threaten Warsaw. Two Austro-Hungarian armies advanced and two held the right flank from Lemberg to the Gnila Lipa River. The Russians drove back one of the two armies and, on 30 August, the Austrian right wing was in retreat while Hindenburg was scoring his victory in the north. The other two Austro-Hungarian armies advancing on Lublin and Kholm were now exposed to the Russian forces advancing through Lemberg to the south of them. The Austrian forces were beaten back before Lemberg in the first week of September. Conrad ordered his forces to take up a position on the San River, which put the fortress of Przemyśl right in the centre of it. By mid-September, the retreating armies had not been able to take up positions on the San and continued to fall back having lost about 400,000 men (half of the troops engaged). Before Przemyśl was surrounded in September, its garrison swelled by about 70,000 men who had retreated from Lemberg. This was more than the fortress’ provisions could support. By mid-September, the remnants of the four Austrian armies had taken up positions between Tarnów, Goryce, and the Carpathian Mountains. Fortress Przemyśl came under siege deep behind the lines. On 18 September, the Russians bombarded Przemyśl as the Austrians abandoned the San River Line and the fortress was surrounded. The Russians bombarded two of the northern forts of the ring, but they had no heavy artillery. During this time, the defenders had dug a trench line that linked all the forts, making it difficult to penetrate the outer ring. During two weeks of fighting, the Russians attempted to storm the Austrian lines and break the ring. Russian infantry only managed to reach the ramparts of Fort I/1 ‘Łysiczka’ where the defenders drove them back and took many prisoners.

Meanwhile, Hindenburg formed a new German army on the left wing of the Austrian armies in Galicia and together they launched a new offensive at the end of September with the intention of taking Warsaw from the south while the Austrian armies in Galicia drove the Russians back to the San River Line by 7 October. During this offensive in late September, a relief force coming through the Dukla Pass finally broke through the Russian lines reaching the fortress on 9 October and being greeted with great celebration.

The German offensive came to a halt about 20km south of Warsaw and failed to reach the Vistula. Thus, by mid-October the Germans prepared to pull back after the 1st Battle of Warsaw. At this time, Conrad pushed the Austrian offensive until it collapsed and another retreat began. The Austrians retreated from behind the San River Line on the night of 4/5 November. Before the retreat, between 28 October and 4 November Przemyśl had received 128 trainloads to resupply the fortress. The advancing Russian forces isolated Przemyśl one more time on 8 November and shortly after took the Carpathian passes. Winter was approaching, and offensives at that time of the year were generally undesirable, especially when mobility was limited by weather and chances of another relief force reaching the fortress before the spring of 1915 were not good.

The Austrians tried to breakthrough with another relief force coming out of the Carpathians in December after recapturing the Dukla Pass. On 15 December, a force of 30,000 troops assembled in the fortress and launched an attack in a southwesterly direction to break out of the encirclement. Even though it advanced almost 25km (15 miles), this force was unable to go any further and it was 45km (30 miles) short of the relief force coming through the Carpathians. On 19 December, the Russians forced the Austrians back into their fortress. Late in the month, the Austrians attempted another sortie, but they were quickly repulsed. On 23 January, the Austrian 7th Army on the far right flank launched an offensive towards Czernowitz driving the Russians back to the Dniester River. Finally, the Austrian 3rd and 4th Army tried without success to force the Russians back to the San River and relieve Przemyśl, but they were bogged down in deep snow. The Germans were more successful on the left flank striking out of East Prussia, but that did not help Przemyśl. Another sortie was launched from the fortress on 17 February, but it too was driven back, while the Austro-German offensive came to a halt.

The situation in the fortress steadily worsened as food supplies dwindled. The troops started slaughtering the horses for food. The Austrians developed a scheme for flying in supplies, but nothing came of it. One of the aircraft that flew from the fortress carried documents from the fortress commandant, General Hermann Kusmanek, which described a dire situation. Unfortunately, the plane went down and the documents were captured by the enemy. The Russians began a major bombardment of the fortress on 10 March and succeeded in capturing some of its outposts. The Russians finally brought up their heavy artillery, which may have included 280mm guns. On 18 March, a force consisting of Hungarian troops launched a sortie to the east with the objective of capturing Russian supply dumps in an effort to resupply the garrison. It was a fruitless effort because the troops could not even reach the Russian trench line.

With no options left, the Austrians blew up all the bridges and tried to destroy the remaining munitions and the armoured positions of the forts. On 22 March, the garrison of 123,000 surrendered. None of the forts of the fortress had been damaged by either Russian siege. The only damage was inflicted by the Austrians who destroyed many of the positions before surrendering. The Russian divisions that conducted the siege were rushed to the front. Russian forces took the key Carpathian passes and advanced toward the Hungarian Plain until the spring rains mired them in the mountains. Meanwhile, Hindenburg prepared German and Austrian troops for a new offensive in April. At the beginning of May, he launched a massive offensive. The battle for the San River began on 16 May and this time an Austro-German force laid siege to the Russian-held fortress. The Russians resisted for a few days. Heavy artillery including 305mm mortars and a 420mm howitzer pounded the forts until the end of May. The part of the fortress ring involved was between Fort IX and XII on the northern front. Forts VI and VII were hit by 305mm rounds. The Russian garrison capitulated on 5 June. Meanwhile, Russia’s position in the Polish territories weakened as offensives from the Galician Front and East Prussia formed pincers threatening to encircle Russian forces in their Polish territory. Before long, the Russians withdrew their forces and abandoned their own fortresses in a defeat more crushing than the one they had suffered at Tannenberg the previous year. Except for an offensive towards Lemberg in 1916, the Russians would no longer be a serious threat for the remainder of the war. They had been driven far from the German and Austrian forts, which, like the German forts on the Western Front, no longer played a role in the war. Fortress Przemyśl had stood like a rock in an angry sea holding off the enemy for months, and possibly preventing a greater disaster in Galicia and a Russian advance into Hungary.

Italy remained neutral for months, but when the Austro-Hungarian armed forces in Serbia were beaten back by an inferior force and collapsed in Galicia, the temptation to seize disputed territories prevailed. Italy declared war on 23 May 1915. At the time, the Trento Front was held by anything but the cream of the Imperial Army. The Italians launched an offensive with a force that outnumbered the 40,000 defenders by 6 to 1.

The Italians had built several other forts on the front with Austria late in the first decade of the twentieth century to counter the Austrian forts. The first three Austrian forts to engage in battle were Lusern, Verle, and Vezzena. Fort Lusern, nicknamed the ‘Steel Trench’ and considered the strongest in the Austrian line, was surrounded with trenches and barbed wire obstacles at the start of the war, like most of the other forts. The first rounds fired after the declaration of war came from the battery of four 149mm turret guns of Italian Fort Verena early in the morning of 24 May. Several thousand rounds, most of large calibre, struck the fort. The bombardment, which did not stop until 12 June, was heavy and inflicted so much damage on the Austrian fort that its commander raised the white flag. The man was relieved of command when Austrian troops repelled the assault with the help of the adjacent forts. The Italians quickly discovered what others had early in 1914: machine guns devastated ground assaults and those located in forts were the most difficult to suppress.

Fort Campolongo was intended to counter the Austrian Fort Verle and had a battery of four 149mm long-range guns in turrets. Since their fort guns were unable to inflict much damage on the Austrian position, the Italians moved a battery of 280mm howitzers and a 305mm howitzer closer to their target. Many of their rounds missed Fort Verle altogether and struck the nearby town. During the intense bombardment, Fort Verle was virtually destroyed and Italian Alpini tried to take it twice. The first attempt on 30 May took place in the dark and the rain. The attackers and the follow-up troops never reached the fort because they were unable to negotiate the barbed wire barrier covered by the fort’s machine guns. The five days of heavy bombardment had put one of the 100mm howitzer turrets out of action and inflicted major damage on the fort.

Werk Vezzena, perched on a mountain top just north of Fort Verle was also subjected to heavy bombardment during the first month of the war, but most of the enemy rounds went right past it. A company of Alpini tried to assault the position on 30 May at the same time as their comrades were attacking Fort Verle. This attack failed as well, but the Italians managed to take an advanced post of Werk Vezzena.

At the other end of the line, the unfinished Werk Valmorbia fell on 3 June to an Italian infantry attack, but only after a failed attempt on 1 June. The Italians attempted to strengthen the position by digging trenches facing northward, towards the town of Rovereto, one of their main objectives. When the Austrians launched a counterattack, the Italians abandoned the fort. During another night attack, the Italian troops mingled with retreating Austrian units in order to reach the fort from the rear. After they eliminated the guards, someone sounded the alarm. For several hours, 2 Italian companies were trapped in a crossfire that eliminated almost all of the 500 Italian soldiers.

On 12 June, Fort Verena was targeted by Austrian artillery, including 305mm mortars placed beyond the range of the Italian guns behind Fort Lusern. The Austrian rounds hit their mark, killing forty defenders and destroying casemates. The problem with Fort Verna, located on a commanding position at 2,015m, was that it was one of the last Italian forts to be built. It was completed in 1914, but the Italians had had to skimp on its construction. Its sister fort, Campolongo, and probably other forts, were also built on the cheap. To cut costs, their concrete was not reinforced with iron. Instead, the Italians had used broken tools, wood, and stones to strengthen the concrete. The gun turrets were only 160mm thick and the flanking batteries of 75mm did not have the required range to reach the Austrian forts. The Austrian mortars knocked out the turrets of both forts and their rounds smashed through the un-reinforced concrete roofs. In July, the commander of Verena was ordered to remove his artillery and place it in open positions.

The Italians renewed their efforts on the Trento Front on 15 August when, once again, they bombarded Fort Verle with 210mm, 280mm, and 305mm guns for ten days. Once they convinced themselves that the fort had been smashed, they sent their infantry on the attack. In fact, only one howitzer turret was operational at the Austrian fort and twenty men had died. The Austrians illuminated the assault troops with their searchlight, sprayed the assailants with their machine guns forcing them to pull back after taking heavy losses, and plastered Italian infantry assembled at Mt Basson with their only working turret. During a respite in the fighting, they repaired the damage to the fort. The Italian offensive wound down at the end of the month after the Alpini were prevented once more from taking Vezzena by the barbed wire barriers and the fort’s machine guns. However, the Italians prevented the Austrians from resupplying the fort during daylight hours from the outpost they had taken earlier. In the spring of 1916, the Italians were driven from this outpost without succeeding in taking Werk Vezzena, which did not surrender until 1918 along with the other forts.

In 1916, it was the Austrians’ turn to take the offensive. Conrad concentrated his forces in the Trento region and assembled what heavy artillery he could get. His plan was to break through the Italian 1st Army and drive towards Vicenza and Venice, cutting the line of communications to the Italian armies on the Alpine and Isonzo Fronts in the east. The offensive opened with an M-11 305mm mortar bombardment of the Italian Fort Verena and Fort Campolongo.

The Austrians repaired the damage to their forts from the 1915 engagements and by the spring of 1916, they had reinforced them with thicker concrete roofs. In 1916, the Austrians brought up two of their new 380mm howitzers named ‘Barbara’ and ‘Gudrun’ and three 420mm howitzers. ‘Barbara’ was set up about 2km north of Fort Lusern, which had been virtually destroyed in April 1916 by another Italian artillery bombardment. The battery site for ‘Barbara’ had escaped untouched. ‘Gudrun’ was delivered later in April. When the offensive began on 15 May, ‘Gudrun’ was assigned to bombard Werk Matassone and Valmorbia, which had been captured by the Italians early in the war. The two guns joined the 305mm mortars in an attack on forts Verena and Campolongo. Werk Sommo supported the advancing infantry by bombarding Italians positions. For many weeks prior to this, the Italians had tried to drive a mine gallery under Fort Verle, but the Austrian offensive ended that effort as the Italian forts fell to the Austrians. The Austrians held these forts for the rest of the war.

Conrad’s plan looked good on paper, but the mountainous terrain was not easily traversable. The Italians pulled back from the towns of Asiago and Arsiero, leaving only one mountain barrier between the Austrian forces and their main objective, the plains of Northern Italy. The exhausted Austrian troops were unable to go any further after advancing almost 20km in some sectors. On 16 June, the Austrians gave up over half of the ground they had gained in the face of a counterattack from Italian reserves. In addition, a Russian offensive toward Lemberg forced Conrad to transfer some of his divisions from Trento to Galicia. During another, but more limited Austrian attack on 2 July 1916, the Italians smashed Werk Serrada with 280mm howitzers located in the Borcola Pass and halted the Austrian advance. In September, Italian infantry tried to recapture Werk Valmorbia, but they abandoned the attempt when they lost the element of surprise. This part of the front remained stable for the rest of the war. It is difficult to estimate how much difference the Austrian forts made in holding this front because the terrain itself is a formidable barrier and it can be defended with field works alone.

The Allies broke up the empire at the end of the war and the new Austrian republic had little in the way of modern fortifications. In the 1930s the Austrians prepared certain sites with mainly field positions and barriers to block an enemy advance. Italy and the new nations of Poland, and Yugoslavia inherited what remained of Austria’s most modern fortifications, while Hungary and Czechoslovakia took over much older ones.

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