Was Mata Hari framed?

It's more than 80 years since she was shot, but history's most notorious seductress and spy still provokes strong passions - not least because new evidence suggests that Mata Hari was innocent

In October 1917 – a year in which hundreds of thousands of men died pointlessly in the cause of one flag or another – a woman was shot by a military firing squad in the forest of Vincennes, east of Paris. She was a dancer, not a soldier. She came from a country that was not engaged in the Great War (a war that would not, as promised, end all wars). By contrast to most of the other faceless victims of 1917, her life and death have acquired with the passing years an aura of romanticism, a mystique, partly based on embellishments and inventions (including her own). She claimed to be the daughter of a British lord and an Indian princess; others claimed she was the lover of the Crown Prince of Germany and the German spy chief. It seems she was a prototype of 20th-century liberated woman – a Mae West or Marilyn Monroe – who seized independence and notoriety through manipulating and pleasing men.

The real story is extraordinary enough. Her name was Margaretha Geertruida Zelle-McLeod, a Dutch adventuress, exotic dancer and courtesan, better known by her stage name, Mata Hari (a name under which she invented the strip-tease in 1905). She was executed, at the age of 41, after being convicted, by a closed court-martial, of passing military secrets to the Germans.

Next week, for the first time, most of the documents presented at her trial – originally due to be locked away until 2017 – will be published in France in a new book, Mata Hari, espionne ou victime? (Spy or victim?, Editions Italiques). They will be accompanied by a new and expanded edition of a book first published in 1994, which makes a convincing case for Mata Hari's innocence.

On the basis of this evidence, the town of Leeuwarden in the northern Netherlands (her birthplace), and the Mata Hari Foundation, a body based in the same town and devoted to clearing her name, petitioned the French government this week to re-open her trial. A decision is expected early next year.

The author of the revised book, Leon Schirmann, an 82-year-old retired French physics teacher and amateur historian, has spent 10 years ferreting through the archives of the French, German and British governments. (Mata Hari was twice arrested and questioned by M15 and Special Branch in 1915 and 1916.) Himself a hero of the French Resistance, he believes that Mata Hari was the victim of a "patriotic lie" by the French military establishment: that she was a convenient distraction from the military disasters and civilian privations of 1917, a year in which the French army mutinied and the allies contemplated, for the first time, the possibility of defeat. She was the "perfect victim", he says, because she was foreign, manifestly immoral and a woman who lived a high life while French soldiers were dying in the mud of the Chemin de Dames and French civilians were going hungry and cold.

One of the many stories spread by her military accusers was that she bathed in milk, "at a time when there is not enough milk for our children". There is no evidence that she ever did so, but it is clear that she liked to live in some style. When briefly arrested by the British in 1916, she was travelling with 10 trunks of luggage, containing, among other things, 11 pairs of shoes and 33 pairs of stockings.

Mata Hari was also accused of betraying the existence of the British secret weapon, the tank. Tanks in fact took the Germans entirely by surprise when they were first used on the Somme in the autumn of 1916. She has also been accused of delivering allied shipping into the hands of U-boats and directly causing the deaths of at least 50,000 soldiers. None of these accusations came up at her trial.

Schirmann says that 1,000 pages of documents were "presented" to the judges. Nothing in them proves that Mata Hari was spying for the Germans in 1916; some of the documents directly suggest that she was by then, as she claimed, a spy for the French. However, the military judges reached their verdict on the basis of a summary which gave, Schirmann says, a grossly misleading account of the evidence.

The picture that emerges from Schirmann's book is of an extraordinary woman who re-invented herself several times over; a woman who symbolised the freedom and hypocrisies of turn-of-the-century Paris but failed to grasp that the world had changed in 1914. Until the day of her execution, she seems to have believed her charms, personal and physical, would enable her to muddle through.

She had a particular weakness for men in uniform. She once said that she would rather "sleep with a poor officer than a rich banker". It was this weakness – and her curious mixture of worldliness and naivety – which proved her undoing.

Margaretha Zelle, the 18-year-old daughter of a hat manufacturer down on his luck, re-invented herself for the first time in April 1895 when she answered an ad for a wife placed by a Dutch officer of Scottish extraction, Rudolph McLeod. After her marriage, she emigrated to the Dutch East Indies where her husband proved to be a libidinous scoundrel. Their small son, Norman, was poisoned by a servant, allegedly because McLeod had raped a young local woman. The unhappy couple returned to the Netherlands and separated. Rudolph seized custody of their daughter, Non. Margaretha, penniless and bored, drifted to Paris in 1903.

Here, she re-invented herself a second time as an exotic oriental dancer, disguising her real identity and taking the name Mata Hari (which means "eye of the day" in Malay). Her act was a pastiche of oriental dances, in which she wriggled sinuously in front of a spoof idol as she removed her veils. This proved a great commercial success. She appeared in a number of European capitals, gradually being accepted as an artist, rather than just an exotic dancer. She also became a courtesan, with scores of paying lovers.

When the First World War started, Mata Hari found herself in Berlin about to start a new show. She was expelled, having been relieved of her money and several fur coats. Back in the Netherlands, in 1915, she was approached by the Germans to go to Paris as a spy. She agreed and accepted 50,000 francs – to get back what the Germans stole from her, she insisted later, rather than with any serious thought of spying on the French.

She made two trips to France in 1915 and 1916. On both occasions, she was closely watched by two rather Clouseau-like inspectors from French counter intelligence, who produced no credible evidence she was spying. On her second visit, she fell in love with a young Russian officer, Vladimir Maslov. This relationship seems to have been the one true love of her life. It may also have led to her death.

The French counter-intelligence chief, Georges Ladoux, made contact with Mata Hari, and tried four or five times in 1916 to persuade her to spy for his side. She eventually agreed to go to Belgium and seduce senior German officers in return for a million francs. She told Ladoux she needed the money so she could settle down with Maslov and give up her other paying lovers. (All of this is faithfully recorded in the documents prepared for the trial but flagrantly traduced in Judge Bouchardon's summary, which accuses Mata Hari of approaching French intelligence and having no real romantic attachment to the Russian.)

She set off for Belgium via Spain but her ship was stopped by the British in the Channel and she was returned to Madrid. Here, she seduced – or so she thought – the German intelligence attaché, Arnold Kalle, and gave him a series of vague pieces of gossip about the French conduct of the war. In return, he gave Mata Hari some barely more useful pieces of German information, which she sent to the French. Major Kalle reported Mata Hari's fatuous "information" – "The British are now running France" – to Berlin using a code that he knew had been broken. His intention seems to have been to betray her to the French in order to punish her for embezzling Germany's money. The French, it turned out, were only too happy to play along, for reasons of their own.

Mata Hari was arrested when she returned to Paris in February. Schirmann says that French counter intelligence, the French military and the French government seized on the opportunity to turn the immoral foreigner, Mata Hari, into a wicked master-spy. She was tried behind closed doors in July and condemned to death.

Even her execution is cluttered by myths. It is still sometimes reported, quite seriously, that she bared her breast or blew a kiss to the soldiers in the firing squad (her last men in uniform). The journalists who attended saw nothing of this kind. The French newspapers stated that Mata Hari had confessed in prison.

Eight decades later, Schirmann has recovered some of the censored journalists' reports from the official archives. They recorded that Mata Hari died, still protesting her innocence, wearing an elegant black, fur-lined dress. One journalistic eye-witness wrote that "she displayed unprecedented courage, with a small smile on her lips, just like in the days of her great triumphs on stage".

Schirmann himself was given a death sentence when he was diagnosed with cancer five years ago, and told that he had only months to live. He says his crusade, his passionate quest to correct the wrong done to Mata Hari, is "the only thing keeping me alive".