https://www.history.com/this-day-in-history/mata-hari-executed?cmpid=email-hist-tdih-2020- [login to see] 0&om_rid=
There is some evidence that Mata Hari acted as a German spy, and for a time as a double agent for the French, but the Germans had written her off as an ineffective agent whose pillow talk had produced little intelligence of value. Her military trial was riddled with bias and circumstantial evidence, and it is probable that French authorities trumped her up as “the greatest woman spy of the century” as a distraction for the huge losses the French army was suffering on the western front.