Having become a major general, he was one of the brief ministers of War (from September to October 1898) in the cabinet of Henri Brisson during the Dreyfus Affair. During the Rennes trial related to this affair (where he testified for the prosecution) in August and September 1899, he learned through the press about the massacres committed by the Voulet-Chanoine mission in Africa. This was a military expedition commanded by his son Julien Chanoine, who was later killed by his own colonial troops.
He then fought to uncover the circumstances of his son's death, clashing with the military administration that sought mainly to protect the honor of the army. His resignation from his ministry, without warning, at the podium of the Chamber on October 25, led to the fall of the government on October 26, 1899. Sir, I am extremely touched by your intention to come on Saturday to Baudement with M. I will have the honor of waiting for you on the day you wish to indicate, Saturday, June 8 in the afternoon.
" Carefully sent Return accepted Chanoine Jules, letter, Bandolent, 1901, manuscript, autograph, signed, M. Le Doyen de Rouilly, historical document, correspondence Chanoine Jules, letter, Bandolent, 1901, manuscript, autograph, signed, M.