Blasting the Schwalleck

MAGYARUL

Despite the fact that sirens throughout the city had given half an hour's notice of the historic event, the explosion of the Schwalleck rock in Grein, which overlooks the Danube, caused serious collateral damage. Collapsed walls of apartment blocks, roads buried by debris and damaged railway embankments signalled the beginning of the process of making the "Austrian Iron Gates", the infamous Strudel Strait, navigable. 

The Schwalleck peninsula. A detail from the map of Strudengau. (Leopold Franz von Rosenfelt, 1721.)

The term "Austrian Iron Gates" is no coincidence, the Strudengau in Austria was as much a dreaded passage for sailors as the Iron Gate, Islás or Tachtalia on the Lower Danube. On this 25-kilometer stretch, the Danube cuts its way through the 300-million-year-old granite cliffs of the Bohemian Massif between Ardagger/Dornach and Ybbs/Persenbeug, where the rocky reefs and the whirpools they create have caused the destruction of many ships, for example between Wörth and Werfenstein. Just as the (second) regulation of the Iron Gates began in 1890 with the blowing up of a symbolic rock, the Grében, so the regulation of the Strudengau began with explosions, the first being the castle of Donaudorf on the right bank near Ybbs on 20 December 1955, and the second being the blowing up of the left bank of the Schwalleck promontory near the town of Grein in Upper Austria.

Outlook from the Schwalleck towards the town and castle of Grein.

Until Friday, 13 June 1958, at 12.30 pm, the Schwalleck Cliff reached far into the Danube, and in a very bad place, for navigation, as the drift line of the river led ships travelling downstream straight into it, while above it, at the mouth of the Greinerbach, a shoal was formed where flating ice were regularly stuck, and the cross-section of the river at the cliffs was also narrowing, causing the river to speed up, which made life difficult for sailors heading in the opposite direction, towards Linz. Geographically, the 250-260 m high Schwalleck was a counterpart to the cliff on which Grein Castle was built at the end of the 15th century, and these two heights defined the local skyline, the town of Grein being either depicted from here or depicted as being on the picture. It was about 40 to 50 meters above the Danube's zero level.

The doomed Schwalleck, and the evacuated buildings at its foot. (source)

It was originally topped by a cross called Halterkreuz, the origin of which is told in a local legend: a shepherd from Grein used to graze his cattle near the cliff during high water. While grazing, he was trying to fetch scrap wood out of the flood, which he wanted to store for firewood during the winter. When he tried to drag a large branch ashore, he slipped and fell into the water. Unable to swim, he desperately squeezed the drifting branch and, fearing for his life, vowed that if he managed to escape, he would place a cross on the shore to the glory of God. The river eventually swept the branch ashore, where he managed to cling to a tree hanging in the water and was lucky to escape. He kept his vow and the so-called Shepherd's Cross stood at Schwalleck Cliff until the explosion. [1] There was another cross here, the Schwalleck Kreuz, which was also destroyed by the blast, but was later reerected on the side of the cliff face opposite the Halterkreuz [2]. 

The moment of the explosion (source)

Austria's first hydroelectric power plant on the Danube was built jointly with Germany between 1952 and 1956, on the border between the two countries, just next to the unique Jochenstein cliff, which fortunately was not blown up along with the statue of St John Nepomuk on it. Austria then began to barrage the Danube, and construct the next power station which was located at the lower end of the Strudengau, between Ybbs and Persenbeug, precisely because of the navigability of the Strudengau. 

On 11 June 1958, the mayor of Grein sent out a leaflet informing the population of the impending explosion. The precaution was certainly justified, as there were already inhabited houses less than 100 metres from the Schwalleck cliff, which the town did not wish to demolish. Some nearby structures had to be sacrificed, such as those built at the base of the cliff. Doors and windows had to be left open, parked cars were removed, and valuables and furniture were moved to the far corners of the rooms for safekeeping. However, due to the proximity of the site, the blast caused significant damage to the city [3]. 

Landscape after the blast (source)

On that day, 5,800 kilograms of explosives blew up the cliff, from which more than three hundred thousand cubic meters of stone were then extracted in several stages, ensuring the unobstructed flow of ice and the necessary width of the shipping lane. Interestingly, a small cliff was left as a memorial between the Danube and the new main road, and the Shepherd's Cross was put back on it when the works were completed. Since then, the vegetation has conquered the cliff, the cars the new route and the boats the less dangerous bend in the river. The Ybbs-Persenbeug hydroelectric power station has raised the water level by 11 metres at the power station, about 5 metres at Wört and slightly less at Grein, and has removed the rapids, reefs and cliffs of the Strudengau. There is now no threat to navigation on the uniform river.  

The boulder of Halterkreuz left as a memento (forrás)

Everyone seems to have well served. If you're passing by, you don't miss anything, as if everything was already like this. What we don't know doesn't hurt. To those whose hearts we might have hurt by this old story, we apologise. 

But we will continue.  

Translated with DeepL.com (free version)

Danke an die Autoren des Österreichischen Donaubuchs für die Idee!

[1] https://www.grein.at/Tourismus/Sehenswuerdigkeiten/Halterkreuz

[2] https://www.grein.at/Tourismus/Sehenswuerdigkeiten/Schwalleck_Kreuz

[3] https://www.im-fundus.at/das-greiner-schwalleck-gefuerchtetes-schifffahrtshindernis/

Where the Amber Road Crossed the Danube

MAGYARUL

Stopfenreuth is probably not one of the best-known settlement names along the Danube, even in Austrian terms, and the riverine forest on the outskirts of the village, which barely belongs to Engelhartstetten, might even seem like the end of the world from Vienna, even though in ancient times one of the arteries of European trade, the Amber Road, ran crossed the Danube here. There is no visible evidence of the site's importance in the muddy riverine forest today, but when archaeologists scratch the sediment layers of the Danube, they come across ancient Roman walls.  

The tower of the military camp, unlike what we are used to, was located inside the wall.  

On 20 February 2025, the website of the Donauauen National Park published an article that archaeologists from the Carnuntum Museum and the Austrian Archaeological Institute had discovered a Roman fortress in the Stopfenreuther Au area of the Austrian national park. To be more precise, only what was left of it by the Danube; a short section of wall in the northern corner of the military camp, together with the base of an inner tower. The island, called Stopfenreuther Au, is located on the left bank of the Danube, in fact in the Barbaricum, opposite today's Bad Deutsch-Altenburg, but slightly to the north-east of the ancient legionary camp of Carnuntum. Excavations began towards the end of the vegetation season in order to minimise disturbance to wildlife, as the ruins lie on the floodplain, under 0.5-0.8 m of sediment, which is now completely covered by a vast riverine forest.

The fine-grained Danube sediment, which covered the ruins in thick layers, is clearly visible.

The Boris flood on the Danube in September delayed and hampered the work, but the excavation was completed in November, the trenches were reburied and, despite the fact that the Roman fortress (unlike Hungary) has been a World Heritage Site in Austria since 2021, the national park has requested that the vegetation be allowed to reoccupy the strictly protected area. This will be followed by an evaluation of the finds, which will hopefully shed light on the circumstances of the fort's construction and destruction, and will allow conclusions to be drawn about the hydrological conditions of the period, since archaeology is currently unable to say for certain on which bank of the river this Roman military camp, which was largely destroyed by the Danube, was originally built.  

The Stopfenreuth excavation in 2024 as seen from above.  

Erőd-ellenerőd példákat a Duna számos pontjáról ismerünk a római kori Pannoniából, Brigetioval szemben ott állt az izsai Leányvár, Pestről ismert a Március 15. téri erőd, a kisebb kikötőerődökről nem is beszélve (Dunakeszi, Nógrádverőce, Dunaszekcső, stb.) Stopfenreuth-nál alig maradt valami a római erődből, de a meglévő falszakasz alapján egyértelműen látszik, hogy kiserődről van szó, nem pedig kikötőerődről, erre utal a fal íve és az ív belső oldalán épült trapéz alaprajzú torony, sőt a toronyalap helyzete alapján azt is feltételezik, hogy ez nem egy későrómai építmény, amikor a patkó alakú tornyokat az erőd falsíkjához képest kívülre építették. 

Examples of fortress and counterfortress pairs are known from many places on the Danube from Roman Pannonia; the fortress of Leányvár in Izsa opposite Brigetiovo, the fortress of Március 15. square in Budapest, not to mention the smaller harbour fortresses (Dunakeszi, Nógrádverőce, Dunaszekcső, etc. ) At Stopfenreuth, hardly anything remains of the Roman fortress, but the existing section of wall clearly indicates that it was a small fortress, not a harbour fortress, as is indicated by the trapezoidal tower built on the inside of the arch and the position of the base of the tower, which suggests that it was not a late Roman structure, when the horseshoe-shaped towers were built outside the wall plane of the fortress.  

Location of the Ödes Schloss fortress and the ferry crossing on the III. military survey (1870s)

Although all the remains of the fort are covered in floodplain sediment, the ruins were not unknown to archaeologists, with substantial wall stumps still standing on the bank in the 1860s. Where the Danube had just cut through the walls of the fortress, a cross-section of the stone wall was cropped out perpendicular to the bank, and the places where it was built were referred to by several names, one of the most common being 'Ödes Schloss', or Desolate Castle, a name that also often appears on maps, However, there were also expressive hydrological names, such as 'Hungerstein' or 'Durstkugel', which refers to lean years with significant draughts, as their appearance was probably related to record low water levels. 

The archaeological interest in the nearby legionary camp of Carnuntum (Bad Deutsch-Altenburg) and its civilian settlement (Petronell), despite the three kilometre distance, was the main reason why excavations were carried out here relatively early, at the end of the 19th century (1896, 1898, and 1900), when researchers already assumed that it was an important element of the fortified Roman Danubian border (ripa) connected to Carnuntum. The figure below shows the same section of wall as the one excavated in the autumn of 2024. On this site, archaeologists fount the brick stamp of the leg. XV Apollinaris, a legion known to have been stationed in Carnuntum between 9-61 AD and 73-117 AD, i.e. either the camp was built at this time or the building material was reused at a later date.

Site plan of the 1898 excavation.

Between Klosterneuburg and Bratislava, the Danube meandering through the Marchfeld was once a major obstacle to north-south traffic. This 60-kilometer stretch of the Danube cannot be characterised by a single main riverbed, which widens to 4.5 kilometres in places, where the constantly changing pattern of tributaries, backwaters, gravel bars and islands made it virtually impossible to create permanent crossings until the river was regulated. At Carnuntum, however, this Danube floodplain narrowed slightly, with the Kirchenberg limestone block, which emerged as a peninsula, forming a flood-free surface directly on the bank of the main branch, while at Stopfenreuth the floodplain narrowed to 1.7 km. This is still a relatively large distance, but the generally lower Danube water levels of Roman times allowed the establishment of a river crossing, which was an important cross-continent economic artery of antiquity, leading to the Baltic amber deposits from Aquileia. 

The stump of a section of wall destroyed by the Danube.

At the time of the first archaeological excavations between 1896 and 1900, the section of the fortress wall formed a spur in the Rosskopf branch of the Danube, and behind it the backwash formed a small bay in the inner part of the fortress. At the end of the 18th century, the Rosskopf branch was even wider than the branch that washed the high bank of the Carnuntum, now the main branch. Generally speaking, the river's course was constantly changing due to its course, and there were no two maps alike in that the islands, gravel bars or the banks are in the same position, which is why the cartographic representation of this stretch is much less accurate than that of other, more stable stretches of the Danube. The confluence of the two branches was generally at the foot of the Kirchenberg, where, according to contemporary maps, a ferry crossing operated. The southern crossing point of the ferry occupied a fixed position in the northern part of Deutsch-Altenburg, but on the northern bank the ferry port was constantly in flux, where it landed on the island surrounded by the Rosskopf branch, but mostly landed at the Ödes Schloss, suggesting that the crossing continued to operate after the loss of the importance of the Amber Road, albeit with less traffic.

The route of the Amber Road between Aquileia and the Danube border.

Geographical considerations were the main reason for the route of the Amber Road between Aquileia and Carnuntum, which avoided mountainous areas impassable in winter and was as close as possible to them, it had to cross as narrow a watercourse as possible in the province of Pannonia, the Sava at Emona (Ljubljana), the Drava at Poetiovo (Ptuj), the Mura and then the Zala at Sala (Zalalövő), the Raba south of Savaria (Szombathely) before reaching the Danube east of Carnuntum (Deutsch-Altenburg). At this point, it is assumed that there was a temporary pontoon bridge, which was replaced by a ferry crossing in the Middle Ages and modern times. After 1951, this was replaced by a cable ferry, which also transported cars. The latter was a relatively brief moment in the history of the crossing, and in January 1973 a new Danube bridge was inaugurated on the site of the crossing, which since 2012 has borne the name of the Lower Austrian Landeshauptmann Andreas Maurer, the only bridge between Vienna and Bratislava to date. The fact that the bridge now crosses the Rosskopf branch where the Roman army built the military camp almost two millennia ago says a lot about the Roman engineers' choice of location. 

Translated with DeepL.com (free version)

Source of news, pictures: 

• https://www.donauauen.at/aktuelles/news/das-roemische-brueckenkopfkastell-in-der-stopfenreuther-au
• https://de.wikipedia.org/wiki/Kleinkastell_Stopfenreuth
• https://www.lobaumuseum.wien/cms/erinnerung-an-die-rollfaehre-bad-deutsch-altenburg/

The Castle in the Middle of the Danube

 MAGYARUL

Spielberg castle on the Danube / Litography of Jacob Alt

It's not necessarily the Inség (Hunger) stone at Budapest that comes to mind when talking about rocky islands on the Danube, but rather the Babakai cliff on the Lower-Danube, or Jochenstein on the German-Austrian border. There were also island forts on the Danube, Ada Kaleh was perhaps the finest example, with its ramparts and bastions almost occupying the entire island on which it was built, until it was sunk by the "progression". However, there is another island in the Danube that fulfils both criteria, a rocky promontory and a castle, built in the middle of the Danube. Today, Spielberg's castle is a little difficult to find; it has been moved from the middle of the Danube by river regulation and is hidden in the middle of a riverine forest on the left bank of the Danube at river km 2116, opposite to the town of Enns in Austria.

 Ruins of Spielberg in 1840. (W. Mossman, W.H. Bartlett)

Spielberg castle on Matthias Vischer's engraving, 1674 (source)

Spielberg castle in 1650., sr. Matthäus Merian's engraving (source)

Without the river regulation works, it could be a true castle for hydrologers, ideal for landlords exploring the Danube, as an icebreaker fixed point in the middle of the ever-changing floodplain archipelago between Linz and Mauthausen. On the slower-flowing stretch behind the granite cliff jutting out of the riverbed, gravel bars, sandbanks and islands have formed and transformed after each flood, taking on a new shape. The Danube's turbulent, swirling course over the smaller reefs made navigation in the northern tributary difficult, as did the construction of the castle. 

Originally, Spielberg's granite cliff may have been closer to the right bank of the Danube, as evidenced by the Roman archaeological atrifacts found on it. The legionary camp of LAURIACUM at the mouth of the river Enns, where the veteran Roman soldier St Florian was pushed off the bridge with a millstone around his neck, was situated opposite. The discovery of Roman relics is no less sad a story, as the 1940/41 excavation season was carried out by prisoners from the Gusen concentration camp, a part of the Mauthausen Lager. Prior to that, in the 1930s, in keeping with the spirit of the times, the courtyard of the ruin had been the site of so-called knightly ceremonies held by local Nazis.

The Enns estuary and Spielberg Castle in the middle of the river (drawn by Charles de Feignet)

Spielberg Castle is almost a thousand years old, the earliest part of it dating back to the first decades of the 12th century. It was probably already on an island in the Danube when it was built, as its owners used it primarily as a castle of refuge rather than a residence. In times of war, this impregnable fortress was used by its lords as a refuge for their families, treasures and other valuables. Perhaps that is why its owners treated it like a hot potato, its first half-millennium of history being one of constant changes of ownership. It has been privately owned, owned by ruling families, the Babenbergs, the Habsburgs, and has been owned by various ecclesiastical estates, of which Regensburg was perhaps the most distant, with St Florian's monastery the closest. In 1619 it was a Danube toll-house, but the inhabitants of the castle were fond of plundering Danube sailors shipwrecked on the granite cliffs. Interestingly, the destruction of the castle was not due to siege, fire or frequent changes of ownership, but to the neglect of the longest-standing Weissenwolff family, who owned the castle and later its ruins until 1961. 

The oldest part of the castle is the late Romanesque tower, originally five storeys high, which was added two storeys higher in the early 1500s when the outer castle wall was built. The age of the engravings in the entry can also be determined from the collapsed roof structure in 1840. The best preserved part of the castle is the outer castle. A forester still lives here and carries out basic maintenance work.

The castle on the 1st military survey (1773-1781)

The castle on the 2nd military survey (1809-1818)

The castle on the 3rd military survey (1869-1887)

Parallel to the gradual destruction of the castle in the 18th century, a process was taking place in the Danube riverbed that was slowly removing the castle from the middle of the river. The main riverbed was shifted by the development of the bends to the Enghageni branch, south of the castle, and the 19th century river regulation preserved this situation, which was made worse by the construction of the hydroelectrical power plant between Abwinden and Asten, where the floodplain forest that was home to Spielberg Castle was located directly below the dam, and the drying out of the river had a major impact. The small tributaries forming the archipelago were filled up and the forest covering the different levels of geomorphology grew on the alluvium. To complete this process, Spielberg Castle was officially transferred administratively from Enns to Langenstein on the left bank on 1 January 1997. Spielberg Castle is still privately owned and a local NGO was established in 2013 to maintain and preserve it.

Spielberg castle as it seen today, south from the Gusen bridge (Google)

However, even if they succeed in restoring the castle, the Danube is unlikely to be diverted back to the lonely granite cliff, so the floodplain castle will not again become a unique hydrological curiosity; an island castle on the Danube. 

Translated with DeepL.com (free version)

Three Sentences on Haynau

IN HUNGARIAN

True, it has nothing to do with that Haynau, born in Kassel, Germany, but there was an island of that name on the Austrian section of the Danube, namely west of the castle of Wallsee, roughly opposite Mitterau/Ledererhaufen, which was nominated in the 2023 Danube Island of the Year vote.

Haynau on the Danube (mapire.eu)

Now that the 150 years have passed and it is safe to write about this island, which originally belonged to Upper Austria, it is worth mentioning first that Haynau (also known as Hain Au, or, in English, a Danubian sandbank with groves) is, like many of its Austrian Au counterparts, a young landform, because, like the Gemenc region in Hungary, islands and reefs on this originally braided stretch of river were very often born, disappeared or transformed.

Haynau was formerly part of a larger river bend, Grünau, in the south, and only later became an 'independent' island, sometime in the 1870s, as it first appears on the sections of the 3rd military survey, while its present form as a tied peninsula is due to the Wallsee-Mitterkirchen hydroelectric power station, built between 1965 and 1968, which eventually connected it to the Lower Austrian riverside.

Record discharge measured on the Drava!

The record discharge on the Drava was surpassed today. At the city of Ptuj they measured 3100-3200 m³ per second, which surpassed by 500 m³ the highest ever measured value of 1965. To compare this data, the Danube's discharge at Budapest was 1760 m³ recently. Within days they can observe at the mouth of the river a rare hydrologic phenomenon, when the fourth largest tributary of the Danube will deliver twice as much water as the main river.

 

Lavamünd under water, 06. 11. 2012. (photo: Standard.at)