What is the author's perspective in The Last Duel?

This book is a historical account of the case of Jean de Carrouges and Jacques Le Gris, the two men who fought the last Parlement-approved judicial duel in Paris. The author, Eric Jager, wrote from his own perspective, basing his account on many historical documents from various sources. Though Jager did not write in first person, it is important for the reader to remember that he wrote from his personal perspective.