His most recent work, 2021's Hero of Two Worlds: The Marquis de Lafayette in the Age of Revolution, received similar praise, earning its own spot as a New York Times Best Seller.

[9] In 2018 Duncan relocated to Paris, France in order to do research for his 2021 book Hero Of Two Worlds, a biography on the Marquis de Lafayette.

"[10] Regarding modern history, Duncan has predicted that Silicon Valley may be seen in the future as groundbreaking as the Renaissance was, stating that "we have lived in the last twenty years through some of the most impressive advances in human civilization.

Benjamin Wittes, after hearing the first two episodes of Revolutions, called the podcast "informative, engaging, told in Duncan's usual easygoing, somewhat comic style that packs a lot of history into relatively brief discussions".

[21] Mike Duncan is believed to have coined the phrase "the entropy of victory" to describe the recurring division that occurs following a successful revolt, or coup d'état, among the victors.

In their description: "Bestselling authors and historians Mike Duncan and Alexis Coe are far-flung buddies who slice through centuries with the sharpness of a guillotine.

In this wide-ranging series, Duncan, best-known for The History of Rome and Revolutions, and Coe, a presidential historian and senior fellow leave no stone unturned, no sacred cow un-tipped."

[27] In an interview with the Washington Post Worldview, Duncan claimed his aim for the book was to "pull back two generations [from the time of Caesar] and ask, 'What was it that opened the cracks in the foundation of the Republic?

Benjamin Wittes of Lawfare wrote, "Never has a book about history that's two millennia old been so timely...You'll learn as much about the problems we face today from this book as from any newspaper",[29] and a review in the Huffington Post praised his "congenial style", claiming that he "zeros in on Rome's polarization between "optimates" (conservatives) and "populares" (populists), the disintegration of participatory democracy, and the concomitant rise in inequality, uncivil discourse, and violence.

The book was published 24 August 2021 and in September of that same year, it reached number three on the New York Times Best Seller list.

[34] Duncan has also expressed interest in developing a TV series based on the biography, having drafted a pilot script for the proposed show.

[35] Duncan appears as a panel historian on seasons two and three of the Netflix documentary Roman Empire,[36] and was a historical consultant for The Simpsons' episode I, Carumbus.

[37] In July 2022, Duncan released, through his Revolutions podcast, a one-man table read of a script he created for a proposed Marquis de Lafayette TV show.

[40] Similarly, Peter Adamson mentioned Duncan as one of the reasons he started his History of Philosophy Without Any Gaps podcast.

[41] Rian Johnson was listening to the History of Rome podcast as he was writing the script for Star Wars: The Last Jedi.