The Fehmarnsundbrücke, and the Cold War Threat

I recently wrote about the Rødby to Puttgarden train ferry, linking southern Denmark to northern Germany.  This route opened in May 1963 and slashed journey times for both rail and road transport between København and Hamburg.  Yet it was also a lesser-known part of the Cold War story.

The two ferry terminals were built at the points of each country nearest each other, which both happened to be on islands in the Baltic.  One of the consequences of this is that any journey from Denmark to Germany via this route not only necessitates a ride on a ferry – well, for the foreseeable future at least (construction of a fixed link will begin in 2018) – but leapfrogging a number of islands along the way.

Accordingly, the infrastructure that required constructing in 1963 was not confined to the ferry terminals and their associated roads and railways, but also two substantial bridges.  On the Danish side, there was the Frederik IX Bridge linking the islands of Falster and Lolland; on the German side, there was the Fehmarnsundbrücke linking the island of Fehmarn, on which Puttgarden port stands, and the German mainland.


The Fehmarnsundbrücke carries a two-lane road, a single-track railway, and a pedestrian walkway.  It is 963.4m long and is high enough for ships to pass under, and was built as a replacement for the little ferry that used to shuttle from the mainland to Fehmarn.  It was formally opened on 30 April 1963, although when severe weather had caused the suspension of the Fehmarn ferry three months previously, people had been permitted to use it at their own risk.  Its engineers were G. Fischer, T. Jahnke and P. Stein from the firm Gutehoffnungshutte Sterkrade AG based in Oberhausen, with architectural design overseen by Gerd Lohmer.

Lohmer (1909-1981) was a renowned West German architect who specialised in bridges.  In the wake of World War 2, he found gainful employment in bridge design – either on the reconstruction and redesign of bridges damaged in the conflict (e.g. the Nibelungenbrücke in Worms), or on brand new ones (e.g. the Konrad-Adenuer-Brücke in then-capital city Bonn).  In recent years, it has been granted the status of a protected national monument, and is well-loved by locals, who have nicknamed it the “Kleiderbügel” (clothes hanger) due to its distinctive shape, and adopted it as a local symbol.

The story would probably end here, were it not for the complicated and heated political environment which existed at the time of the bridge’s construction.

Photo from by Matthias Mueller (

In 1963, the Cuban Missile Crisis had only just passed and the Cold War was still at very real risk of turning “hot”.  The threat of a Soviet invasion of West Germany was one which was taken very seriously.  The area to the east of Fulda – termed the “Fulda Gap” – was generally considered to be the route the Soviets would most likely take if they invaded – as there was little by way of natural barriers to a massive tank attack.  However it was not the only possibility.

Denmark’s stance in the Cold War is a complex but interesting topic.  Breaking a tradition of neutrality, it was a founding member of NATO in 1949, which meant it courted hostility from the Soviet Union who now treated it as an enemy.  Denmark could well have held strategic importance for the Soviets – not least could it have constituted something of a stepping stone to Greenland, from where its nuclear warheads could have reached the USA – but also a way into neutral Sweden – from where Norway, and thence the North Atlantic, would have been feasible targets.  Sweden boasted strong coastal fortifications, intended to defend it from a Soviet attack, therefore an “entrance” via Denmark would have been a clever way for Warsaw Pact forces to circumnavigate them.

Occupation of Denmark would have put West Germany – and from it the rest of Western Europe – within easy reach.  The existence of the newly-constructed train ferry would have made the movement of rail based forces, armaments, supplies, and so on much easier.  Equally, it could have formed a route for Soviet forces that had already conquered West Germany, into Denmark.  In either event, the Fehmarnsundbrücke may have taken on an immense strategic importance.

As a result, the design of the bridge featured six “Sprengschächte” – or “explosive vaults” – beneath the tarmac of the road’s surface.  In the event of an invasion, explosives could be placed into the vaults by soldiers and then detonated remotely (from a military location approximately a mile away), thereby causing significant disruption and delay to the advance.  Fortunately, this was never required.  However, the remnants of the Sprengschächte can still be seen today – in the form of six patches of darker tarmac on the surface of the road, at the mainland end of the bridge.  You can actually see them in very brief passing on my video above – although here is a far more useful photo!

These were by no means the only Sprengschächte that were placed on German roads for this purpose.  Indeed, whole hosts of them existed in the Fulda Gap and were officially maintained up until the early 1990s and the reunification of the two Germanies.  However the fact that these existed within the design of such a famous structure makes them noteworthy indeed.

Today, trains from Hamburg and Lübeck to Puttgarden (most of which continue across to Denmark via the train ferry) as well as high volumes of road traffic, continue to thunder across the bridge, their passengers most likely unaware of what used to lie beneath.


HMS Onslaught, 1960-1991

D832 "Onslaught" nameplate

Isn’t it strange to know that something is historically significant, but that most of us may never find out exactly why?

Today I enjoyed a ride behind the only currently operational ex-British Railways “Warship” Class locomotive – no. D832 Onslaught – at the East Lancashire Railway, a heritage railway centred on the town of Bury, roughly 10 miles north of Manchester.

The “Warships” were born out of the British Railways Modernisation Plan of the mid-1950s – directly replacing steam traction on the routes of the former Great Western Railway – and were essentially a scaled down version of the highly successful West German V200 class.  In the best tradition of the GWR, they all carried names on a theme – in this case, Royal Navy vessels – the irony being that these locomotives of impeccable German pedigree were named after a number of particularly renowned ships that, just 15 years previously, had played key roles in the defeat of Germany in World War 2.  Indeed, the destroyer HMS Onslaught herself was a veteran of convoys both in the Atlantic and off Scandinavia (where she was credited with putting the finishing touches to the destruction of the U-boat U-472 which scuttled itself in March 1944) and also of the D-Day landings in Normandy.

Following the sale of the destroyer HMS Onslaught to the Pakistani Navy in 1951, the name has been re-used by the Royal Navy just once – for an Oberon class submarine, pennant number S14 – which was coincidentally launched from Chatham Dockyard exactly 56 years ago today: Saturday 24th September 1960 – is of the same vintage as the locomotive, and is the subject of these ramblings.


The Oberon class were conventionally (i.e. non-nuclear) powered patrol submarines and were designed as a key British weapon for the Cold War.  At 295ft in length – equivalent to the proverbial football pitch – and carrying a crew of 65, they were sizeable enough beasts, yet intended to be stealthy, hunting down their Russian peers preferably without being detected.  Being both smaller and quieter than their nuclear counterparts, these diesel-electric submarines were deemed more appropriate for this type of work.  A total of 27 were built – 13 for the Royal Navy, with others for Canada, Australia, Brazil and Chile.

Following commissioning in 1962, HMS Onslaught first saw active service from Singapore during the Borneo confrontation (when fighting broke out after the creation of Malaysia in 1963) then during the British withdrawal from Singapore later in the decade.

However, it is what happened later in her life which is open to conjecture – the details remain classified information.  What is commonly accepted is that HMS Onslaught and her sisters spent a considerable amount of time in the Baltic Sea in the late 1970s and throughout the 1980s, engaged in clandestine operations against the Soviets at the height of the Cold War.  Iain Ballantyne in his book “Hunter Killers” recounts how HMS Onslaught once spent seven weeks in the Baltic with 17 intelligence specialists crowded on board, alongside her usual crew.  It has even been reported fairly extensively that British submarines even sent commandos ashore in the Soviet Union.  That in itself would be interesting enough, but it has also been suggested that commandos were secretly sent ashore to neutral nations on the other side of the Baltic – Finland and, particularly, Sweden.  These two countries formed a buffer between NATO and the Soviet Union and therefore were, usually passively, politically volatile during the Cold War.  They would definitely have been a target for Soviet invasion if they decided to mount an offensive heading West.  Sweden was aware that there were submarine incursions into its territorial waters on an increasingly frequent basis as the 1980s progressed – these were generally accepted as being of Soviet origin – but could they in fact have been Royal Navy?  Perhaps they were testing Sweden’s responses and anti-submarine infrastructure, to investigate what may happen if the Soviets did actually attempt an invasion?  The entire Cold War was shrouded in mystery and (particularly) suspicion, even of one’s own “friends”.

Britain has apparently publicly maintained that its Oberons were never in the Baltic.  They certainly have not admitted to any such covert operations within Scandinavia.  But the very fact that any information on the broad subject remains top secret, might be taken by the cynics among us as a hint that there remains something worth hiding…

What might HMS Onslaught and her sister vessels have been looking for?  More importantly, what might they have found?  It is possible that we will never find out, but equally, it is possible that our entire understanding of the Cold War may shift if we do.

HMS Onslaught was decommissioned in 1990 and scrapped in Turkey in 1991.  However, eight Oberons have survived in various forms around the world, and a number can be visited – although just one of them is in the UK.  Whereas HMS Onslaught was the penultimate Navy warship manufactured in Chatham, and did not survive; the final one, HMS Ocelot (S17), has returned “home” to the Kentish town, to form an important part of the Historic Dockyard Chatham attraction.  HMS Ocelot, too, retains her Cold War secrets – one day, we may know more about the service life of these enigmatic vessels.