In 1778, Philippe served in the squadron of the Count of Orvilliers. He was present in the Battle of Ushant, a naval battle against the British during the American War of Independence on 27 July 1778. He was removed from the navy due in part to the queen's hatred of him and also to his own incompetence and alleged cowardice. As compensation, he was given the honorary post of colonel-general of hussars.