Passage: The Dreyfus family, particularly his brother Mathieu, remained convinced of his innocence and worked with the journalist Bernard Lazare to prove it. In March 1896, Colonel Georges Picquart, head of counter-espionage, found evidence that the real traitor was Major Ferdinand Walsin Esterhazy. The General Staff, however, refused to reconsider its judgment and transferred Picquart to North Africa.

Question: Who betrayed everyone?
Major Ferdinand Walsin Esterhazy