The Jablunkov incident

In the early hours of 26 August 1939, six days before the outbreak of war, an armed group in civilian clothes attacked the railway station at Mosty near Jabłonków (Jablunkov), right by what was then the Polish–Slovak border. The attackers seized the station building, took a dozen or more prisoners and tried to capture the nearby railway tunnel under the Jablunkov Pass. They failed, and after a few hours they withdrew into the mountains, onto Slovak territory. They were a raiding party of German military intelligence, the Abwehr, led by a reserve lieutenant, Hans-Albrecht Herzner (PL). Their task was to open the way for the Wehrmacht in the first hours of a war which, according to the order issued the previous day, was to begin that very morning. On the evening of 25 August, however, Hitler had halted the attack, and the news never reached Herzner’s men, who were already on their way.

Popular war chronologies say that word of the postponement did not reach “Germany’s allies” and that it was they who attacked Poland. This is inaccurate. The raid was carried out not by the Slovak army or by any other state allied to the Reich, but by a unit subordinate to the German military. Slovakia served merely as a base: the group set out from its territory, from the area of Čadca, where German troops were concentrating in August 1939. Most of the saboteurs were local Germans from Cieszyn Silesia and the Sudetenland, recruited and trained by the Abwehr.

A tunnel on the border

The Jablunkov Pass, which separates the Silesian Beskids from the Moravian-Silesian Beskids, is one of the most important crossings of the Western Carpathians. Through it runs the Košice–Bohumín Railway, the shortest rail link between Silesia and Slovakia, and on to Hungary. Just beyond the station at Mosty the line enters two parallel tunnels about 300 metres long. Until 1938 they lay in Czechoslovakia. At the beginning of October 1938, after the Munich Agreement, Poland occupied Zaolzie – the Trans-Olza area – and with it Jabłonków, Mosty and the whole stretch of railway up to the pass. From then on the Polish–Slovak border ran just beyond the southern mouth of the tunnels.

In March 1939 the situation of this corner of the country changed fundamentally. Germany occupied the Czech lands, Slovakia declared independence and, in a treaty of protection, handed the Reich control over its foreign and military policy. The Wehrmacht could now concentrate troops in northern Slovakia, and the Polish–Slovak border became in practice another stretch of the border with Germany. Case White (Fall Weiss) provided for an attack from this direction too. The 7th Infantry Division of General Eugen Ott, assembled around Žilina, was to enter Poland through the Jablunkov Pass. An intact tunnel would have allowed the Germans, from the first day of the war, to move troops and supplies by rail into the rear of the Polish defence of Silesia. Destroyed, it would close that route for many months.

The Polish command was well aware of this. As early as June 1939 sappers of the 21st Sapper Battalion from Bielsko mined both tunnels. The work was directed by a reserve lieutenant, Witold Pirszel, a mining engineer by profession, who had been mobilised specially for the purpose. All summer long, every night after the last train had passed, the sappers armed the charges, and every morning they disarmed them. The tunnel was guarded by officers of the Border Guard (PL) post at Świerczynowiec and by soldiers of the 4th Podhale Rifles Regiment (PL) from Cieszyn, while the nearest National Defence battalion was stationed at Třinec (Trzyniec). The sector belonged to the 21st Mountain Infantry Division of General Józef Kustroń.

The Abwehr saboteurs

Germany’s preparations for war with Poland did not involve the army alone. From the spring of 1939, Abwehr Department II, responsible for subversion and sabotage, had been forming so-called combat groups (Kampftrupps, K-Trupps). On the night before the attack they were to cross the border in civilian clothes, seize bridges, tunnels, railway junctions and industrial plants before the Poles could destroy them, and hold them until the army arrived. They were recruited above all from members of the German minority who knew the terrain and the language. After the Polish campaign, such groups grew into the celebrated special operations unit Brandenburg.

Hans-Albrecht Herzner, born in Potsdam in 1907, was by training a historian of Eastern Europe: he had obtained his doctorate in 1938, and his study of socialism and the labour movement in nineteenth-century Poland was published in 1939. As a reserve officer he was posted to the Abwehr station in Breslau and joined the circle of Admiral Wilhelm Canaris. In August 1939 he was given the task of seizing the station at Mosty and the Jablunkov tunnels, disarming the Polish explosive charges and handing the pass over to the 7th Infantry Division. His unit, about 30 men strong according to Polish studies, consisted mainly of members of a secret combat organisation active among the Germans of Jabłonków (Kampf-Organisation Jablunkau), who had been trained in Slovakia. Other sources give figures ranging from twenty-odd to around 70 men. Some of them were reportedly wearing Polish uniforms, which would have been a flagrant breach of the Hague Conventions.

At around 3 p.m. on 25 August Hitler gave the order to attack Poland at dawn the next day. In the evening Herzner’s group set off towards the border. A few hours later, after news of the signing of the Anglo-Polish alliance in London and Mussolini’s letter saying that Italy was not ready for war, Hitler halted the attack. The countermanding order reached most units, but not the saboteurs making their way through the mountain forests. Their radio sets had no contact in the deep valleys of the Beskids, and attempts to find them by runners failed.

Night at Mosty

After a march of several hours across the ridges around Velký Polom (PL), the saboteurs came down into Mosty between three and four in the morning on 26 August. From a nearby hill they fired on the station building and on the neighbouring house of the head of the Polish school, where the sappers were quartered, and then seized the station. They detained a dozen or more railwaymen and workers on their way to the morning shift at the Třinec steelworks. What they failed to notice, however, was a military telephone exchange operating in the basement of the building. The telephonist on duty managed to alert the Polish command to the attack.

The shooting also alerted the tunnel’s garrison. Soldiers, border guards and sappers took up positions at both entrances and opened fire on the attackers. The saboteurs were unable to reach the charges or take over the tunnels. Accounts of what happened next differ. According to German sources, based mainly on Abwehr reports and later memoirs, Herzner’s men disarmed several hundred Polish soldiers brought to the station by train, and one of them drove a locomotive through the tunnel to Slovakia, tearing out the detonator cables on the way. Polish historians, relying on documents and the accounts of the defenders, regard these stories as exaggerated: the Germans occupied only the station building, and not even all of it, while the tunnels remained in Polish hands throughout.

In the morning Herzner finally made contact with the staff of the 7th Infantry Division at Žilina and learnt that the army was not coming, because the attack had been called off. Under Polish fire the unit withdrew on foot into the mountains, towards Skalka and Velký Polom. Around midday it crossed the Slovak border. According to some studies, the Germans had two wounded. A similar raid had been prepared against the tunnel under the Łupków Pass in the Bieszczady Mountains, but there the countermanding order reached the saboteurs at around 3.15 a.m. – after the first shots, but early enough for the affair not to grow into an incident.

Apologies

General Kustroń demanded an explanation from the German side. A Captain Kreisel came to the talks and insisted that the raid had been carried out not by the Wehrmacht but by armed members of the German border guard. The Polish general, offended by the envoy’s low rank, replied that such an incident could have had incalculable consequences, since the Polish soldiers had been held back in their positions only with the greatest difficulty. Soon afterwards the commander of the 7th Infantry Division, General Ott, formally apologised for a “regrettable incident”, supposedly caused by a deranged individual acting on his own initiative. Kustroń nevertheless agreed to release the people detained in connection with the affair.

The Polish government did not publicise the matter. Standing orders were not to respond to provocations and not to give the Germans a pretext for accusing Poland of starting the war, and Britain and France were urging Warsaw insistently to show restraint. For the Polish command, however, the incident was a warning that the German preparations were far more advanced than had been supposed and that war could break out at any moment. The emergency mobilisation ordered on 23 August in the districts along the German border was extended to further units on 27 August.

In Germany there was official silence about the raid. Canaris proposed Herzner and his men for decorations, but the Chief of the OKW, Wilhelm Keitel, is said to have refused because the war had not yet begun. Herzner received the Iron Cross Second Class only later, as one of the first Wehrmacht officers to do so in this war.

The first shots of the war?

The Jablunkov incident is sometimes called the first commando operation of the Second World War, or even its first engagement. The latter description is an exaggeration, since the war in the legal and military sense began only a week later, but the events at Mosty show clearly how close Europe was to war in the last days of August. German troops were already at their start lines, and some of them, like Herzner’s group, had set out to fight. Hitler had called off the attack, but not his intention to go to war. He used the six days’ pause for a last attempt to separate Britain from Poland, and in the meantime the Wehrmacht continued its concentration.

The affair also laid bare the method the Germans meant to use: the war was to begin even before the official attack, with operations by men in civilian clothes recruited from Polish and Czechoslovak citizens of German nationality. The Polish authorities, who had for months been following the activities of clandestine German organisations, now had hard proof that the fifth column was no invention of propaganda. In those same days the Abwehr was preparing further attacks and acts of sabotage in the rear of the Polish defences.

What followed

On 1 September 1939, when Germany really did attack Poland, units of the 7th Infantry Division again advanced on the Jablunkov Pass. This time the Polish sappers were ready. At around six in the morning, a few minutes before the Germans arrived, Witold Pirszel blew up both tunnels. The Germans partly restored rail traffic on the line only in February 1940, and fully in 1941. That same morning Abwehr sabotage groups, operating on the same pattern as Herzner’s unit, struck at many places in Silesia and Pomerania, trying to seize mines, steelworks, bridges and railway junctions before the Wehrmacht arrived. In Upper Silesia they were beaten off in the first hours of the war by former Silesian insurgents and Scouts.

The experience of Jabłonków and of the Polish campaign was put to use in the autumn of 1939 in creating the Brandenburg unit, which in the following years operated in the same way in the Netherlands, Belgium, Yugoslavia and the USSR. In 1941 Herzner commanded the Nachtigall Battalion, made up of Ukrainians and Germans, which entered Lwów (Lviv) in July that year. For decades the battalion was accused of taking part in the crimes committed in the city at the time, including the murder of the Lwów professors; today historians attribute responsibility for the murder of the professors primarily to the German Security Police. Herzner died in September 1942 at the SS sanatorium in Hohenlychen, in unclear circumstances. General Kustroń was killed on 16 September 1939 while leading his soldiers in an attempt to break through near Oleszyce. A plaque commemorating the attack on the station at Mosty was unveiled in 2022.