FORTRESS STUDY GROUP

Casemate 76

John Goodwin.

Illustrations by the Author.

From 1815 until 1918 the military frontier between the old Austro-Hungarian Empire and Italy crossed the northern end of Lake Garda. The lake is 52km long, but only 3km wide at this point where it is enclosed by high mountains. The fortifications here do not compare in importance with those around Peschiera and Pastrengo at the flatter end of the lake; even so they are not without significance, for within a small and compact border area they exemplify changes in design that were needed to keep up with developments in defensive tactics and artillery elsewhere in Europe. Riva, sited strategically at the head of the lake, was a port and commercial centre for the movement of goods up the valley of the river Sarca and through the mountains into Germany and it was this that led to its fortification.



Barrier forts sited round the head of Lake Garda.

After the departure of the French armies, the Austro-Hungarian policy for the permanent defence of their Riva frontier region was accomplished in four phrases. Between 1850 and 1862, the construction of barrier forts St Alessandro, St Nicolo, Nago, Pannore and the Tommaso Redoubt was undertaken in the mountains around Lake Garda. The first two forts overlooked the Sarca river valley and the lake, and the other three controlled traffic along the Torbole road and passage through the Loppio and Gresta valleys. Further inland similar small forts were built at Tonale, Giudicarie (Lardaro) and the Ledro valley. They were said to reflect the then current French school of fortress architecture, being built of stone blocks and standing proud of the ground. As smaller works there was usually no elaborate exterior protection other than a ditch. Referring to the purpose of barrier forts in the Alps, Sir George Sydenham Clarke said that:


'they were to provide not only a passive obstacle but to serve as a base for mobile forces capable of cutting the communications of an invading army which had passed by, or to compel that army to detach a large number of troops to guard its rear'.


The fortress artillery was mounted en barbette and designed to impede the passage of infantry and cavalry. At Lake Garda these forts remained in use for many years; some were subsequently dismantled, but others were enlarged or modified in the early years of the last century.


The second phrase is represented by the building of a new and substantial work, the Battery Mezzo, on Mount Brione in 1898. Four years later the Austrian government completely revised its views on the importance of defending Lake Garda and decided that the port of Riva should be surrounded by a girdle of armoured barrier forts commanding land exits from the lake. This third phase of fortification led to two new works, Forts Garda and Tombio being built, and at the same time improvements were made to the existing defences.


The fourth and final phrase came about because of an anticipated threat from Italy, which became reality when seeking to extend its borders, that country declared war on the Austro-Hungarian Empire in May 1915. This led to the building of new fortifications, Forts Bellavista, Teodosia, and a substantial underground complex of tunnels to seal off the Ponale Road from Italy. Although there was delay in implementing a plan for improving existing defences, the Austrian High Command policy decreed that the following four strategic objectives should be met:


1. The creation of an autonomous Riva fortress with supporting infantry defences and lines of field works in depth.
2. Closure of all communication through the Adige Valley and the flat country of Torbole to Linfano, and across the Cameras Valley to Lake Loppio.
3. Closure of the passage along the Sarca Valley and up the Ballino pass to the north of this valley.
4. The northern end of Lake Garda was to be defended against an attack coming up the lake from the south.




To achieve these objectives the Austrian military engineers chose Monte Brione as the kingpin of their permanent defence scheme. Wedged between the Sarca River and Riva this isolated mountain is an unusual semi-circular slab of rock, 3km long and 376m high, with a precipitous cliff on the river side, but descending on the other with steep terraces covered in olive trees to the town of Riva in the west. Not only does it have excellent visibility and clear fields of fire for miles around, including down the northern end of the lake, but it also had four older works of different periods which could be modified to strengthen the new field defences which were planned for this sector.



As a result the entire northern end of the lake was turned into a heavily fortified zone with the permanent fortifications reinforced with field works several miles in depth. Apart from a few traces these last have largely disappeared or been built over. The permanent fortifications which remain today merit a fuller description.


Monte Brione: Fort St. Alessandro


On the highest point of Mt. Brione overlooking the small town of Arco and the valleys which sweep down from the Apennines mountain range is Fort St Alessandro, described as an old-fashioned work. It was built close to the cliff edge in 1860-62 by the Austrians and its guns were ranged to fire across the valley 350m below towards the town of Arco 3 km away. It was one of the first generation forts built in the Trentino region. Subsequently because of its good all round visibility its chief function became to act as a signal station communicating with the surrounding forts on this part of the frontier. It stands on the peak of the mountain, built with heavy stone blocks, above ground, and without casemates or armoured cupolas. The entrance is through a medieval style gateway and it was armed with four 12cm calibre guns mounted en barbette. In the early C20th it was rearmed with a 15cm cannon and a magazine for two AA guns. In 1911 a radio telegraph station with a high mast was built over one of the magazines and this is still in use today, such is the commanding position of the fort, which soon became obsolete, for during the 1914-18 war batteries were emplaced outside the fort to support the field defences in the valley below. These were named as the Nord, (North) or Gampedell batteries and they were protected from assault by trench systems, belts of barbed wire and blockhouses, whose remains are possibly hidden amongst the undergrowth or along the banks of the Sarca River.



Monte Brione: Battery Mezzo.


At the end of the C19th the Austrian military high command decided to reinforce Fort St Alessandro, by building a second and more modern fort; Mezzo Battery. A compact fort, its design was based on principles which had been generally adopted in Europe as a consequence of the progress in developing heavier artillery and munitions. Thus it was totally enclosed, with a low profile and sunk partly into the ground.



Mezzo Battery (front) in 1908, with 12cm guns.




Mezzo Battery; the derelict front in 2004.




The guns were mounted in casemates, and its roof was protected by concrete on which there was a revolving observation cupola. It stood about halfway along the precipitous edge of the mountain between Fort Alessandro at the top and Fort St Nicolo on the lake shore at the bottom, hence its name, Middle Battery. Several versions of a design were prepared and the one finally chosen was a squarish shape with a projecting wing on the north side to enfilade the ditch and entrance. The fort was built deep into the cliffside with some exposed walling of stone and granite on the land side. Internal arches supported the roof which had a one metre covering of concrete under a blanket of earth and stones. It was described as a second generation fort in the style of the Trentino region with some medieval features, presumably referring to the drawbridge over the ditch which surrounded it on the flanks and land side. On the cliff front overlooking the Sarca river are four casemates a few metres back from the sheer cliff edge. The main armament overlooked the Loppio valley below and comprised four 12cm guns (1876 model) emplaced in casemates, sited to fire towards Torbole and Mt Baldo. In one corner of this side of the fort is an observation cupola now concreted over; inside the fort there was accommodation for a garrison of 70-80 men on two floors. The rear of the fort stands proud of the ground and today its grey bulk is visible from the top floor of some of the Riva hotels.



Mezzo Battery (rear), under construction c1898.




Mezzo Battery in 2004.




In 1915 some alterations were made which included excavating another observation casemate from the vertical rock face below the fort overlooking the Sarca river. At the north end of the building a large partly ruined blockhouse projects in an L shape and both walls of the angle have embrasures, some suitable for small cannon which serve to protect the entrance; part of the ditch has now been filled in or is much overgrown. The side wall overlooking Riva has several embrasures for a light armament of rifles and machine guns, but the ditch and steep fall of the ground beyond would make an infantry assault hazardous. Most of the building seems sound although the fronts of the main gun casemates are in a broken and ruined state. Access to the interior is difficult and probably dangerous.
The principal purpose of Mezzo Battery was to control the fire zones which included the mouth of the Sarca river where it enters Lake Garda, movement in the wide Loppio valley, and that part of the lake close to Torbole and Fort Nago.



Monte Brione: Fort Garda.


Further down this steep side of Mount Brione towards the lake shore is a third phase fort, Fort Garda built in 1907-8 to strengthen existing Austrian frontier defences with the latest of modern fortifications. This fort stands 4m from the cliff edge and about 600m up the mountainside from Fort Nicolo at the bottom. It is visible from the west but cannot be seen from the lake or the Linfano valley to the east, which lie several hundred metres below. It is of an irregular oblong shape, about 400m long and roofed over in concrete after excavating its site out of solid rock. Inside there are long galleries under arched floors, with barrack accommodation for 150-200 men. The rear of the fort which faces towards Riva has gun casemates which fire westward.



Fort Garda; rear gun casemates; caponier in foreground.





The entrance, also on this side, is protected by a deep narrow ditch about 7m wide and by the natural fall of the ground. Strong caponier type structures enfilade the ditch. Both the ditch which surrounds three sides and the rear of the fort are heavily overgrown with tall trees and bushes and the roof and some of the walls are deteriorating and covered in vegetation. Access to the interior has been roughly blocked off and investigation would be dangerous. The main armament comprises four armoured cupolas intended for 10cm howitzers, which are now concreted over presumably for protection against vandals and the weather.



Ft Garda; 10cm cannon, armoured turret, 1908.




Ft Garda; the sites concreted over, 2004.




The roof of the fort stands just above the footpath level on the cliff edge, making access easy. Outside the fort is an observation cupola also concreted over, and in the undergrowth nearby are emplacements for four 30cm mortars and some pillbox-like structures.
In its operational role with clear fields of fire the guns in the revolving turrets could swing towards Riva and Monte Rocchetta in the west and across the river Sarca to Lake Loppio in the east. The gun ranges are shown on Austrian military maps of the period and cover these areas well.



Monte Brione: Fort St Nicolo.


Fort St Nicolo stands on the shore below where the cliff face of Mt Brione slopes down past Fort Garda to the lakeside. Its function was to defend the lake against an Italian attack, to give enfilading fire towards the port of Riva and to control traffic along the road between Riva and Torbole, which now passes through the cliff at this point.
First generation, (1859) built of limestone blocks in the French style, the fort stands completely above ground, with rounded ends to deflect shells, and there is an adjacent bastion for a gun battery (Torbole battery), which juts out slightly into the lake from the shore. It was built on the instructions of the Austrian Minister of war in 1859, but by 1914 is described in military plans as alles werk, or old work. The walls are pierced with two levels of embrasures for cannon and numerous rifle loopholes.



Fort St Nicolo, 2004, shown on the plan as 'alles werk'.




In 1911-12 the Austrian engineers enlarged and modernised the fort and built new gun batteries on the cliff behind, strengthening existing walls and buildings with concrete, and adding magazines and barrack accommodation; a pre-existing villa also formed part of the site. This extension was named Felsbatterie (Cliff battery) although it remained part of the original Fort St Nicolo.





The original armament is said to have comprised four 15cm cannon en barbette, four 8cm rapid fire guns, searchlights, and machine guns. In 1880 a pit for a mortar battery was dug, trained on the road below. Today the original Fort St Nicolo building is well preserved and stands on part of a yachting compound and car park. Its exterior can be walked around and the Torbole battery and some of the cliff walls and foundations of the battery on the cliff behind are accessible, but not the villa, which is private property.



The fortifications on the NE Bank of Lake Garda.


The north east military border between Austria and Italy ended on the slopes of Mount Baldo close to the shore of Lake Garda at a point 10km south of Riva. Fortifications on and around the eastern shore were deemed necessary to flank the forts on Mount Brione and to deny an enemy access inland to the Linfano and Loppio valleys. Thus away from Lake Garda to the east along the Loppio valley were other older small forts or redoubts, now described as ruins, including Fort Pannore at the entrance to the Gresta valley, which was only in use until 1888. The other and more substantial fortification on the east bank of the lake was Fort Nago, standing on a commanding spur of the hillside on the outskirts of Nago village, looking down to Torbole, now a world famous windsurfing centre, on the lakeside. Its construction was ordered in December 1859 and it was completed two years later. It is described as one of the earlier generations of forts based on the designs of the French military school of architecture and is believed to be the work of Tomasini. In appearance it is somewhat similar to Fort St Nicolo of the same date, and was built of superior limestone blocks having some affinity to the stone work of Verona. It was armed with six 10cm and four 12cm cannon and one 15cm gun, although in 1909 the artillery was reduced to four 9cm guns in the fort and two outside in a battery covering the main road to Riva. Its guns were never equipped with armoured cupolas. If war broke out its function was to defend the road between Loppio and Torbole; to support the Mezzo battery on Mount Brione and to control movements in the Linfano valley. It was used mainly as reserve accommodation for troops engaged on guard duties. Finally disarmed about 1914, it is now a protected building which it is hoped to open to the public eventually.



The West bank Fortifications.


It was not until early in the C20th that the Austrian War Ministry decided to complete the defences around this side of Riva and Lake Garda. Undoubtedly the increasing military threat posed by Italy to extend its borders into the Trentino region, rendered this necessary. The small port of Riva huddles beneath the massif of Monte Rocchetta and the smaller Monte Brione. Before its development into a tourist resort Riva was an important commercial and warehousing centre for the transshipment of goods from Italy through the mountain passes into Germany. Its strong C12th moated Scaligeri castle was even used after 1915 by the Austrian army as a military barracks for troops serving on the frontier. On the north westerly outskirts of Riva, to complete the ring of defences protecting the head of the lake, the Austrians transformed Monte Tombio into an entrenched camp and banned civilians from the area.



Fort Bellavista.


Between 1909 and 1914 Fort Tombio, a third generation powerful armoured fort, similar to Fort Garda, was built in concrete on the top of the mountain, (841m) and lower down on the 608m contour line there was a a second smaller independent work named Little Tombio. Both are now deserted and in a ruined state. These fortifications had casemates, and armour plated cupolas with a thickness of 15cm, each mounting a 10cm howitzer. Their function was to support a deep line of entrenchments and belts of barbed wire, stretching across the valley and extending back from the head of Lake Garda for about 4 km. Their guns straddled the roads and river valley of the Varone stream and the Sarca river between Arco and Monte Brione.



Fort Tombio.


Fort Bellavista was constructed by the Austrians on a rocky spur named La Punta, 800m from the entrance to the port of Riva. The fort was really a substantial blockhouse built with rock and concrete into the cliffside, and was garrisoned by the Austrian military to protect the port of Riva during the 1914-1918 war. There were four guns in casemates, machine guns, and a complement of 32.
An iron chain 800m long stretched across to where the Varonne stream emptied itself into Lake Garda. Its purpose was to seal off the port from attack by motor torpedo boats. A bar or restaurant, Grotta Azura, has been built over the site of the fort, but some of the gun casemates are still visible from the lake ferries. Close by, where the harbour chain was fixed to the Riva shore and hidden behind the trees on private inaccessible land, lurks what appears to be a large concrete WWII gun emplacement, sited to fire down the lake.



Sketch of Fort Bellavista about 1918, with emplacements for 4 cannon, and the chain closing the port of Riva.




Fort Bellavista in 2004, now the Grotta Azura restaurant. Evidence of the fort is the pillbox top left of the roof.




A few kilometres further on past Fort Bellavista, and built by the side of the old Ponale Road which twists and turns inland up through the valley towards Lake Ledro, are further substantial fortifications, the last in this sector to be built by the Austrians in about 1913-14. The first of these is Fort Teodosia.



Fort Teodosia.


Standing high on the mountain side Fort Teodosia is mentioned in Italian accounts as being a fourth generation fort constructed by the Austrians as a late barrier fort just before the onset of the 1914-18 war. It is described as a bold work of military architecture and truly representative of the line of resistance built along this side of Lake Garda. It was excavated out of rock, and further protected by encasing parts of it with concrete. This made its three galleries on four levels bomb proof allowing the garrison to move safely between the gun positions, barrack accommodation and observation posts. Its armament comprised four 8cm guns, two with a rapid range of fire across Lake Garda, (the Riva front) and two towards Torbole on the opposite shore. Its purpose was to oppose enemy traffic on Lake Garda approaching Riva, but it could also range its guns on the entrance to the Sperone Valley and support resistance to any advance through it. The fort was connected to a defensive wall with infantry positions, also forming part of the defences of this small valley.



The Tagliata Complex.


Below the mountain side on which Fort Teodosia is perched is the Ponale cutting through which the principal road from Riva and Lake Garda winds in a succession of hairpin bends upwards to Biacesa and Lake Ledro. This route being close to the old border with Italy warranted a strong defensive position to secure the road. It was a late construction, possibly the last in the region by the Austrian military and probably considered necessary because of the onset of the 1914-18 war.



Plan of part of the Tagliata del Ponale tunnel complex.





A complex of underground tunnels, magazines, guard houses and casemates was excavated from the mountain rock face and was not finished until 1916. There were also storehouses, officer and troop quarters, kitchens and observation posts, mostly underground. Two main tunnels with chambers off, linked the gun positions, accommodation and service areas, the works spanning both sides of the Ponale Road; a flight of 200 steps led down to the lakeside and there was a light railway and trolley for hauling up ammunition and supplies.
I was not able to explore this complex, but I believe it is connected to Fort Teodosia on the mountainside above it.


In retrospect, the Riva sector fortifications planned and built by the Austrian military High Command served their purpose well, in deterring an invasion from Italy by this route. In 1915 and 1916 some military action including air attacks on Riva resulted in the evacuation of civilians for their safety, but otherwise nothing of consequence occurred. Later in May 1918 there was a surprise attack on Torbole by a squadron of Italian motor boats when two army magazines were blown up. The area saw no land or lake action in WWII.

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Further information


Information to write this article has been taken from a number of sources. These included a study of local maps and military plans and visits to some of the forts mentioned. Jeremy Crampton helped with the translation of Italian papers. Some literature which is relevant to the area follows:


Sir George Sydenham Clarke; Fortification; 1890
Col. Lord Waveney: The Italian Army; Journal of the Royal United Service Institution. Vol XIX, 1876.
Major Ardagh; The Military Position of Italy; United Service Institution Journal, Vol XXIV, 1880 (from the (Augsburg) Allgemeine Zeitung).
Capt.W A H Hare, DAQMG; The Engineer Arm of the Austro-Hungarian Empire; United Service Institution Journal, Vol XXX 1886.
Col Needham; Between the Chiese & Adige (translated from Rivista Militare Italiana);United Service Institution Journal Vol XLI 1897.
Musco Civico di Riva del Garda; Sguardi Militari sul Garda. (The line of Austrian and Hungarian fortifications in the High Garda and on the Italian frontier).
Prof. G Perbellini; The Austrian Fortifications of Verona; Fortress No 15, Nov. 1992.
Margaret Pinsent; FSG Tour report; Casemate 50, 1997.
Luigi Cortelletti; an article including a map of Austrian Hungarian forts in the Altipiani (I have been unable to find a copy in Britain). Notizie ai Soci No 29 Jan-Feb 1997.