Ferdinand Walsin Esterhazy
Charles Marie Ferdinand Walsin Esterhazy 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 .
Charles Marie Ferdinand Walsin Esterhazy was born in Paris, France, the son of General Ferdinand Walsin Esterhazy who distinguished himself as division commander in the Crimean War. He inherited the prominent Hungarian family name of Esterhzy through his paternal grandfather who was born out of wedlock and brought up under the name of Walsin, but was later acknowledged by his mother after the French Revolution of 1848. This branch of the Esterhzys settled in France at the end of the 1600s and was involved in the military, namely in the organisation of hussar regiments.
Source: Wikipedia