Thinking about espionage in the First World War one of the first names that comes to mind is that of Griet Zelle alias Mata Hari. This week I participated in the making of an international dramatised documentary about her life: The Mata Hari Files. Mata Hari's case was not an unique one. Dutch citizens were in high demand as spies by both warring sides. As neutrals they could travel almost everywhere, from Berlin to London, from London to Paris and back again.
On 15 October 1917 Mata Hari was executed by the French as a spy for Germany. Looking at her French and British dossiers the evidence is staggeringly thin. Scotland Yard Special Branch's chief Sir Basil Thomson was not convinced either. Nowadays no prosecutor would even consider her case. But Mata Hari was not the only Dutch citizen that got entangled in WWI spy games. In total seven Dutchmen were executed for espionage. Two by the British, two by the French (including Mata Hari) and three by the Germans in occupied Belgium.
As far as the two Dutch spies in German service that got shot in the Tower of London are concerned, there is no doubt about their guilt. Willem Roos and Haicke Janssen did spy for the German naval intelligence service Nachrichtenabteilung im Admiralstab also known simply as 'N'. They were part of a large spy network that was set up and led by German secret agent Hilmar Dierks in Rotterdam. He would send more spies to a premature death by execution squad in the Tower of London, until he got arrested by the Rotterdam police.
For more information on the making of The Mata Hari Files click here.