After the assassination of Henry III in 1589, he was among the first to support the cause of Henry of Navarre, but he was suspected of prolonging the civil wars in his own interest. He brought a part of Normandy under subjection, and dissuaded Henry from going into England. He distinguished himself in the battles of Arques and Ivry against the Catholic League. Gontaud was killed by a cannonball at the siege of Épernay on 26 July 1592.