He attracted the attention of Léon Gambetta by writing articles on Balkan politics for the Revue bleue, and joined the staff of the Republique française.

In the République française he waged a steady war against General Boulanger, which resulted in three duels, one with Edmond Magnier and two with Paul Déroulède.

At the time of the original trial, he attempted to secure a public hearing of the case, and, in 1897, he allied himself with Auguste Scheurer-Kestner to demand its revision.

His articles in the Siècle aroused the fury of the anti-Dreyfus party, especially as Reinach was a Jew and was accused by some of taking up Dreyfus's defence on racial grounds.

He lost his seat in the Chamber of Deputies and, having refused to fight Henri Rochefort, an anti-Dreyfus journalist, eventually brought an action for libel against the latter.