Born in Paris, Esterhazy belonged to an illustrious Hungarian family, a branch of which had established itself in France at the end of the 17th century, and the head of which had organized there a regiment of hussars. His great-grandmother had an illegitimate son, who was brought up under the name of Walsin, but who, after she had acknowledged him during the French Revolution, took the name of Esterhazy and settled as a merchant at Nîmes. Two of the sons of this man followed a military career with distinction, and both became generals of division during the Crimean War. One of these two (Ferdinand) was the father of Major Esterhazy.
Charles Ferdinand was left an orphan at an early age, after some schooling at the Lycée Bonaparte in Paris, he attempted vainly to enter the École spéciale militaire de Saint-Cyr. He disappeared in 1865. In 1869 he was found engaged in the Roman legion, in the service of Pope Pius IX. In June 1870, his uncle's influence enabled him to be commissioned in the French Foreign Legion. It was an irregular commission as he had not been an enlisted soldier before. However the start of the Franco-Prussian War in July prevented actions against him. He then assumed the title of count, to which he was not entitled. There being a dearth of officers after the catastrophe of Sedan, Esterhazy was able to pass muster as a French lieutenant, then as a captain, and went through the campaigns of the Loire and of the Jura. Though set back after peace was declared, he still remained in the army. Between 1880 and 1882 he was employed to translate German at the French military counter-intelligence section where he became acquainted with major Hubert Henry and lieutenant colonel Sandherr both to become major actors involved in the Dreyfus case , then, under various pretexts, at the French War Ministry. He never appeared in his regiment at Beauvais, and for about five years led a life of dissipation in Paris, as a result of which his small fortune was soon squandered.
In 1882 he was attached to the expedition sent to Tunis, and did nothing whatever to distinguish himself in it; employed later in the Intelligence Department, then in the native affairs of the regency, on his own authority he inserted in the official records a citation of his "exploits in war", the falseness of which was recognized later. Returning to France in 1885, he remained in garrison at Marseille for a long time. Having come to the end of his resources, he married in 1886; but he soon spent his wife's dowry, and in 1888 she was forced to demand a separation. In 1892, through the influence of General Saussier, Esterhazy succeeded in getting a nomination as garrison-major in the Seventy-fourth Regiment of the line at Rouen. Being thus in the neighborhood of Paris, he plunged afresh into a life of speculation and excess, which soon completed his ruin.
His inheritance squandered, Esterhazy had tried to retrieve his fortune in gambling-houses and on the stock-exchange; hard pressed by his creditors, he had recourse to the most desperate measures. Having seconded Crémieu-Foa in his duel with Drumont in 1892, he pretended that this chivalrous role had made his family, as well as his chiefs, quarrel with him; he produced false letters to support his words, threatened to kill both himself and his children, and thus obtained, through the medium of Zadoc Kahn, chief rabbi of France, assistance from the Rothschilds (June, 1894). This did not prevent him from being on the best of terms with the editors of the anti-Semitic newspaper La Libre Parole, even to the extent of supplying them with information.
For an officer whose original commission was illegitimate, Esterhazy's military advancement had been unusually rapid: lieutenant in 1874, captain in 1880, decorated in 1882, major in 1892, his reports were generally excellent. Nevertheless, he considered himself wronged. In his letters he continually launched into recrimination and abuse against his chiefs. He went still further, bespattering with mud the whole French army, and even France herself, for which he predicted and hoped that new disasters were in store. Esterhazy's bitterness and utter lack of patriotic feeling, along with his fluency in German, were qualities which helped him to become an effective and unrepentant traitor. In Tunis he was judged to have become too intimate with the German military attaché. In 1892 he was the object of an accusation made to the head of the staff, General Brault. In 1893 he entered Schwarzkoppen's service.
According to later disclosures he received from the German attaché a monthly pension of 2,000 marks ($480). He furnished him in the first place with some interesting information about artillery. He pretended that he got his information from Major Henry, who had been his comrade in the French military counter-intelligence section of the War Ministry, in 1876. But Henry, limited to a very special branch of the service, was hardly in a position to furnish details on technical questions. Esterhazy must have had other informants, who were not necessarily his accomplices. For example, his intimate friend Maurice Weil, district orderly officer to General Saussier, and a distinguished military writer and a regular news-hunter. The information furnished by Esterhazy soon became of so little importance that Panizzardi (to whom Schwarzkoppen communicated it without divulging the name of his informant) began to doubt his qualifications as an officer. To convince the attaché it was necessary for Esterhazy to show himself one day in uniform, galloping behind a well-known general. The garrison-major, being entrusted with the duties of mobilization, is always well informed in regard to the details of this subject. But, as far as artillery is concerned (the improvements in which especially interested the German officials), the difficulties which Esterhazy experienced in getting information were very apparent in the text of the bordereau, and in the attempt which he made (in August 1894) to borrow the manuel de tir from Lieutenant Bernheim (of Le Mans), whose acquaintance he had made by chance. However it is troubling that he could have correctly quoted, in the famous "bordereau" which sparked the Dreyfus Affair, a new 120 mm French artillery model and its advanced hydraulic recoil mechanism.
Captain Alfred Dreyfus was picked by the Army as the traitor in 1894, mainly because he was a Jew, Alsatian and Republican, on the evidence of the bordereau. Convicted, he was deported in Guyana. In 1896, Lieutenant-Colonel Picquart, new head of the Intelligence Service, uncovered a letter sent by Schwarzkoppen to Esterhazy. After comparison of Esterhazy's handwriting with that of the bordereau, he became sure of Esterhazy's culpability. In 1897, Picquart gave the evidences to Dreyfus' lawyers. They started a campaign to put Esterhazy in justice. In 1898 an ex-lover of Esterhazy made public letters of his in which he expressed his hatred of France and his contempt for the army. However Esterhazy was still protected by the High staff, who did not want to see the judgement of 1895 put into doubt. In order to clear his name, Esterhazy asked for a trial behind closed doors by French Military Justice (January 10-11, 1898). He was acquitted, judgement which ignited antisemitic riots in Paris. The truth however still managed to make its way into the open. On January 13, Emile Zola published his famous J’accuse.
Esterhazy was discreetly put on pension and fled to the relative safety of the United Kingdom in September 1898 and died there in 1923. In Great Britain, he continued to write in anti-Semitic papers such as La Libre Parole.