His research and teaching focus on ideas of religion and violence, as well as nostalgia and apocalypse, focused on the European Middle Ages and how that period has been remembered by subsequent generations. He currently teaches at Virginia Tech.

He has published several scholarly books and numerous peer-reviewed articles, which have led to invited talks given to universities across the United States, and he has also presented his research at universities in England, Scotland, Germany, France, and the Netherlands. In 2010, he was a visiting researcher at Westfälische Wilhelms Üniversität-Münster, and in 2023, he was the Donald J. Bullough Fellow in Mediaeval History at the University of St. Andrews, UK. He was elected a Fellow of the Royal Historical Society (UK) in 2025.

His public writing has appeared in such places as The Washington Post, Time, CNN, Slate, and MSNBC. He was between 2018-19 a columnist for Forbes, and was a columnist for Smithsonian Magazine between 2020-21. He has appeared as an expert on the History Channel and NPR, and other interviews with him on radio, podcasts, and TV have aired locally, nationally, and internationally.

With David M. Perry, he co-authored: The Bright Ages: A New History of Medieval Europe (Harper Books, 2021). He and David have teamed up again on their latest book: Oathbreakers: The War of Brothers that Shattered an Empire and Made Medieval Europe (Harper Books, 2024).

See his academic CV.