Ferdinand_Walsin_Esterhazy

Charles Marie Ferdinand Walsin Esterhazy (16 December 1847 – 21 May 1923) was an officer in the French Army from 1870 to 1898. He gained notoriety as a spy for the German Empire and the actual perpetrator of the act of treason of which Captain Alfred Dreyfus was wrongfully accused and convicted in 1894.
After evidence against Esterhazy was discovered and made public, he was eventually subjected to a closed military trial in 1898, only to be officially found not guilty. Esterhazy retired from the military with the rank of major in 1898—presumably under pressure—and fled by way of Brussels to the United Kingdom, where he lived in the town of Harpenden in Hertfordshire until his death in 1923.