He was again Minister of War in the Brisson cabinet from June 28 to September 5, 1898. In July 1898, he told the French National Assembly of documents incriminating Captain Alfred Dreyfus. Cavaignac's investigator, Captain Louis Cuignet, later discovered that the critical document was a forgery by Colonel Henry, who admitted his crime when he was questioned on August 30 by Cavaignac. Still, Cavaignac refused to concur with his colleagues in a revision of the Dreyfus prosecution, which would have been the logical outcome of his own exposure of the forgery. Resigning his portfolio, he continued to declare his conviction of Dreyfus's guilt and joined the nationalist group in the chamber of which he became one of its leaders.[1] (He is portrayed in precisely the opposite way in the 1937 film The Life of Emile Zola in which he is depicted as the person who finally discovers the truth and demands the resignation of all those responsible for incriminating Dreyfus.) He also was an energetic supporter of the Ligue de la Patrie Française.