Mata Hari is probably the most famous woman ever associated with espionage. Her name still stands, almost automatically, for secret services, seduction and double games. Look at her case through the historical record, however, and a far more complicated picture emerges than the legend that grew up around her.

She was born Margaretha Geertruida Zelle in the Netherlands in 1876. In Paris, she reinvented herself. She became Mata Hari, an exotic dancer who tied her origins to Java and captivated European audiences with her performances. Before long she was known across Europe and moving in the circles of high society. Mata Hari became a courtesan of that world, keeping company with wealthy and influential men. Her acquaintances and lovers included officers, diplomats, politicians, aristocrats and businessmen. What began as part of her social life would, a few years later, come to matter for an entirely different reason.

When the war began

With the outbreak of the First World War, her travels and her contacts took on a different meaning. Europe was divided between the great powers, and anyone who moved between countries and maintained relationships with people on opposing sides of the conflict drew increasing attention from the intelligence services. Mata Hari was Dutch, and the Netherlands remained neutral throughout the war. That made it comparatively easy for her to move between European countries at a time when citizens of the belligerent states could not. At the same time, her access to military and political circles gave her social life a new significance.
British intelligence began watching her as well. When she travelled through England she was questioned and searched. No concrete evidence that she was engaged in espionage was found at the time. In 1916 she was recruited by German intelligence and given the codename H-21. She was paid, and she was expected to deliver information.

On paper she had the qualities that still matter in human intelligence – HUMINT – today: international mobility, a wide network, and access to people in military and political positions. Her actual intelligence value, however, was almost certainly far smaller than her later reputation suggests. According to French historical sources, the information she passed to the German side had no meaningful strategic weight. In other words: Mata Hari may have been far better at creating access than at actually obtaining valuable information.

France also wanted her on its side

At the same time, French counter-intelligence took an interest in her. Georges Ladoux, a French intelligence officer, saw her contacts with German officers as a potential source of information. Mata Hari agreed to work with the French. That left her in a position intelligence services regard as particularly precarious: in contact with the German side while simultaneously working with French intelligence. In such circumstances the lines between source, agent and double agent blur quickly. In her case, that is precisely what went wrong.

The message that changed the case

In late 1916 Mata Hari was in Madrid, where she made contact with Arnold Kalle, the German military attaché. Shortly afterwards, the German side transmitted messages referring to an agent with the codename H-21. The French intercepted the traffic and identified H-21 as Mata Hari. Combined with what they knew about her contacts and the payments she had received from Germany, the French authorities considered this sufficient evidence against her.

This part of the case still raises questions. One theory holds that the German side knew the traffic could be intercepted and deliberately exposed her. Another is that it was simply a communications error. If the first theory is correct, Mata Hari was not merely uncovered – she may have been deliberately burned. For counter-intelligence, that distinction is decisive. There is a substantial difference between information you uncover yourself and information someone made sure you would find.