27 April 2021

100 years of the (Czech)Slovak Danubian border



In 1910 there were only two Slovak majority settlements on the banks of the Danube. One of them remained in Hungary after the Trianon decision, the other was annexed to Yugoslavia. The fact that there were practically only Hungarians on both sides of the Danube was not a factor in the drawing of the (Czech) Slovak-Hungarian Danube border in 1920. In today's post, we use a series of border maps recently posted on mapire.eu to explore what has changed along the 142-kilometre-long Danube border over the past 100 years. 

Before we start to discuss the changes in the course of the river and its surroundings, it should be noted that since 4 June 1920 the border between Hungary and Czechoslovakia has changed several times. It has changed so much that by the end of this post we may want back the absurd, unrealistic 'Trianon' borders along this stretch.

Before 1920, the Hungarian section of the Danube stretched from the mouth of the Morava river to Ada Kaleh, initially over a thousand kilometres in length. By 1893, this figure had fallen to 997 kilometres as a result of river regulation. Today, the Hungarian section of the Danube is 417 kilometres long (637 kilometres periodically between 1941 and 1944), of which only 275 kilometres are exclusively in Hungarian territory.

The Slovak-Hungarian section of the Danube by right and left bank (source: wikipedia)

On 4 June 1920, at 4:30 p.m., Hungary signs the peace treaty ending the first world war. Under this treaty, the main shipping route on the Danube between the mouth of the Ipoly and the northern administrative boundary of Horvátjárfalu (Jarovce) village south of Bratislava automatically becomes the border between Czechoslovakia and Hungary. The islands are divided between the two countries according to which side of the shipping route (Thalweg) they fall on. This line is not the same as the river's centre line, which connects points equidistant from both banks. And it did not necessarily coincide everywhere with the drift line of the river, which is officially defined as the imaginary line connecting the points of maximum velocity of successive cross-sections of the river.

The demarcation did not take ethnic considerations into account at all. There were Slovaks living along the Danube, but nowhere did their proportion exceed 25% (Dévény, Devín), and in the free royal city of Pozsony (Bratislava) it was only 10%. On the Slovak side, the closest Slovak-majority settlement to the river was Pozsonyhidegkút (Dúbravka) between Dévín and Bratislava, 3.2 km north from the banks as the crow flies. On the Hungarian side, Mogyorósbánya was slightly closer to the Danube, at 3.1 km.

A further ethnic geographical curiosity was that 88% of the Slovak population living in Esztergom County, cut in two by the Danube border, remained in Hungary, as most of them lived south of the Danube in the district of Esztergom. The same was true to a lesser extent in Komárom county, where 58% of the Slovak population remained in Hungary. Perhaps this is why the Entente negotiating delegation seriously considered leaving the Csallóköz, with its 98% Hungarian population, to Hungary. In the end, this was only an idea, as strategic considerations weighed more heavily. Under the Trianon decision, a short stretch of the Danube flowed exclusively through Czechoslovak territory, as Czechoslovakia was given the village of Pozsonyligetfalu (Petržalka), which belonged to the Transdanubia region.
On 2 November 1938, the First Vienna Award largely abolished the Danube border, except for a short section. Since Germany also received two settlements from Slovakia, such as Dévény and Pozsonyligetfalu, the Slovak Danube border was reduced to a short stretch between Bratislava and Szemet (Kalinkovo), which village was returned to Hungary. The capital of the independent Slovakia, Bratislava remained the only exit to the Danube. The border, measured on the basis of a pharmacy scale and taking ethnic relations into account as much as possible, remained in force until 1945. (you can browse this border here)

On 10 February 1947, under the Paris Peace Treaty, the Danube border between Hungary and the re-created Czechoslovakia was restored with one modification: three Transdanubian villages, the so-called Bratislava bridgehead, were transferred to Czechoslovakia. Dunacsún, Horvátjárfalu and Oroszvár were again separated by a strategic idea, as the majority of the inhabitants (mainly in Oroszvár) were ethnic Germans, while the other two settlements were Croatian-majority, with a significant Hungarian minority and a negligible Slovak population. There were plans to include Rajka and Bezenye in Czechoslovakia, but this was not supported by the Peace Conference. In 1947, the length of the Danube River within Slovak territory nearly doubled. As it later turned out, the decision had a disastrous effect on the Danube, which later allowed the construction of the Bős (Gabčíkovo) power station and the unilateral diversion of the Danube in October 1992. After the construction of the "Variant C", many in Hungary believed that since the border between the two states was still the shipping route, Doborgaz, Vajka and Nagybodak had effectively been transferred to Hungary through the diversion of the river. Unfortunately, as we will see, this is not the case, as the Danube border is not like the border of the Ipoly or the Maros rivers, where the border has to be redrawn at regular intervals to follow the changes in the river's channel.
After the long introduction, let's see what changes have taken place along the border in terms of islands. The map sections for the Danube show a close relationship with the 1:5000 scale site plan of the Danube of 1911. The inscriptions have been replaced by Slovakian ones, but there is still a typical phonetic transcription of Hungarian nomenclature, e.g. sihoť instead of ostrov. Since the 1925 version focuses mainly on the boundary line, all other distractions such as drift lines and inscriptions have been removed. 


The Muzslai-island, below Nyergesújfalu on the Slovak side, was still there. Its closed upper side branch has been almost completely silted up in the last 100 years. It will be worth visiting the buried enclosure one day.


The island of Nyergesújfalu was placed on the Slovak side, despite being closer to the Hungarian side. At that time it was much smaller, and the stone dyke to the Slovak coast did not yet exist. Over the last century, the island has grown upstream, and the forest that has grown on the gravel bar is still well marked by vegetation.


The island of Süttő is also on the Slovak side. Here, the stone dyke was already in place. Fortunately, it was later opened up, and the intervention created some interesting alluvial deposits. There are two islands in the Karva bay that have disappeared, one of them was the island of Karva, the other one I could not find a Hungarian name for, called Vrbinová sihoť in Slovak. 


Above Gönyű the situation is getting complicated. The regulation has changed the sedimentation of the river, creating gravel bars in the middle of the riverbed, which later became forested. However, they 'grew' out of the Danube, just along the shipping lane, so the unchanged border line bisects the upper island. 


The next stop is near Ásványráró at river mile 1818. The situation in Gönyű has deteriorated further, due to the Bős hydroelectrical plant's service water channel shown in the initial image. The discharge of the Old Danube has been reduced to a quarter and an eighth depending on the season due to the diversion. Due to the reduced flow the width of the river has halved since 1993. There are wide gravel bars on the river banks where the encroachment of vegetation seems unstoppable. The border is not on the shipping lane, just as ships no longer pass through. 


A part of the Bős dam and the artificially created Slovak Danube region. The meandering tributary system is mostly silted up, forested and gone.


The abandoned Dunakiliti dam was originally intended to divert the Danube. After the Hungarian side cancelled the treaty, the Slovak side built its own facility upstream at Dunacsun, which was made possible by the already mentioned 1947 Paris Peace Treaty and allowed the Danube to be diverted. 


At Dunacsún you can still see the inscription M.O. Hongrie, marking the pre-1947 border line. The settlement, which has a Croatian population, was annexed to Czechoslovakia in 1947, and a dam was built on its outskirts to divert most of the water flow to Bős. It is used to regulate the flow of water into the Old Danube and the Moson Danube. 


We see the former northernmost point of Transdanubia, northeast of Horvárjárfalu, in the Danube. Between 1920 and 1947 this was the point where the Danube entered Hungarian territory, between the 1860 and 1861 river kilometres. Nowadays, this point is 10 kilometres further south, at Dunakilit at river kilometre 1850. This section of 10 Danubian river kilometres have changed the inter-island landscape of the Danube Valley forever. 

It is quite certain that the Danube, the Szigetköz and the Csallóköz would look different if the "Trianon" Danube border were still in force...

Translated with www.DeepL.com/Translator (free version)

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