Translations for fiercely in French

Here are paragraphs from public domain books translated:

The Duc de Sarzeau-Vendôme was shaken with a fit of nervous trembling. The awful truth to which he refused to open his eyes appeared to him in its nakedness and assumed the hateful countenance of the enemy. He clutched his nephew's hands and said to him, fiercely, despairingly:	Un tremblement nerveux agitait le duc de Sarzeau-Vendôme. L’épouvantable vérité à laquelle il refusait d’ouvrir les yeux, lui apparaissait tout entière, et prenait le visage odieux de l’ennemi. Il agrippa les mains de son interlocuteur et lui dit âprement, désespérément :
The Confessions of Arsene Lupin, by Maurice Leblanc	Les Confidences d’Arsène Lupin, de Maurice Leblanc

He helped himself to a cigar and leaned back with a fiercely critical pair of eyes, taking note of the effect which this document would produce.	Et s’étant offert un cigare, Challenger se pencha, farouchement attentif à l’impression qu’allait produire sur moi le document.
The Lost World, by Arthur Conan Doyle	Le Monde perdu, de Arthur Conan Doyle