Brabant farmstead Valkenhorst housed 1943 German spy station

Secrets about site in Geenhoven revealed decades later

VALKENSWAARD, the Netherlands - A rural Brabant estate once owned by a family of Dutch diplomats, played a serious role in the German war effort. Although it soon became known locally that a large farmstead newly built by the Germans in 1943 was actually a concealed bunker, its purpose remained a mystery for decades. Dutch journalist Hans Knap in a recent book based on newly available documents and other information reveals that ‘Forschungsstelle Langeveld’ was used as a sophisticated listening post where the Germans were able to hack into Allied transatlantic telephone conversations.

In 1940, one of the many Dutch properties appropriated by the Germans was the Valkenhorst estate in Geenhoven, a hamlet between Eindhoven and the Belgian border. The owners were the Loudon family with scions at the Dutch embassies in Paris and Washington.

While regular farming at the estate continued, the German Reichspost (postal, telephone and telegrapgh services) established itself in the manor, setting up an experimental listening post. Behind the main house, a huge, directional dish antenna and some peripheral antennas were set up, all well camouflaged. The local public took them for searchlights.

Manor well disguised

A nearby bunker was selected to house the ‘hackers’ and necessary guards, and to expand the listening post. Berlin architects drafted plans to conceal the entire operation within a real farmstead that for all intent and purpose would look like a farm. Construction on the extensive manor began in 1943 and the ‘Birkenhof’ was fully operational by December of that same year. Records show that approximately 500,000 guilders was spent on building the place.

Birkenhof in all exterior details looked like a large two-story U-shaped farmhouse typical of the area. Inside, the manor was well-appointed: it had central heating, a large living room with a fireplace, a large kitchen and spacious dormitories. The expanded bunker held all the technical facilities.

The existence of the pre-Birkenhof bunker was known throughout the area and its location was subsequently made known to the Allies by members of the intelligence resistance group Albrecht. The Dutch underground however never could report on the bunker’s function. American author Ladislas Fargo in his 1971 book ‘The Game of the Foxes’ detailed some of the Reichspost activities in Geenhoven, and the information was also used in the definitive Dutch history of World War II, ‘Het Koninkrijk der Nederlanden in de Tweede Wereldoorlog’.

Birkenhof in fact was an around-the-clock listening post that tapped into telephone conversations between civilian and military leaders and offices in England and the U.S.A. Reichspost technicians also were decoding the messages which then were sent to Berlin, where Reichspost Minister Dr. Wilhelm Ohnesorge put them at the personal disposal of Heinrich Himmler, the leader of the S.S. and after August 1943, Interior Minister.

Calls unscrambled

Even the existing hotline between London and Washington was tapped into on occasion, as the Germans in Geenhoven were somewhat able to unscramble Allied telephone calls. Most of the intercepted conversations however were meaningless, as the Allies were well aware of the possibility that any communications could be tapped - they themselves had been able to break all Japanese codes. British mathematicians in 1940 had been able to break German codes by developing the ‘Enigma’ decoding machine.

Part of the reason the Germans were adept at intercepting the transmissions was the Reichspost familiarity with Dutch technology and equipment. Ever since the beginning of the century, Dutch and German telecommunication systems had closely cooperated and exchanged information and technologies. The Germans had built on that knowledge in 1940 to start up a first telecom listening post inside a youth hostel in the coastal town of Noordwijk.

By the middle of 1944, the Dutch resistance had gathered more evidence about the German presence at Valkenhorst, including details about troop movements and the number of Germans stationed. These evaluations reached Allied command in England which decided to follow up on the matter. Reconnaissance flights in August 1944 showed a peaceful manor surrounded by acres of freshly harvested grain. The RAF dismissed the possibility of a more sinister role. Upon the pressing of the Dutch resistance, a second reconnaissance flight was made a few weeks later. However, before a decision could be made about a possible air strike against the stronghold, the Germans dismantled their equipment and abandoned Birkenhof. Loaded onto twenty trucks, the telecommunications installation was carted off to the homeland, where deep in Bavaria ‘Forschungsstelle Langeveld’ was set up again. Shortly after, Allied forces reached Brabant.