Oathbreakers: The War of Brothers That Shattered an Empire and Made Medieval Europe – How Charlemagne's Dynasty Fell and Why It Matters for Understanding Political Collapse

“Fascinating.” — The Wall Street Journal

“An enlightening portrait of the medieval mindset.” — Publishers Weekly

The authors of The Bright Ages return with a “real-life Game of Thrones” (New York Times Book Review)—the story of the Carolingian Civil War, a bloody, protracted battle pitting brother against brother, father against son, that would end an empire, upend a continent, and redefine the future of European history. 

By the early ninth century, the Carolingian empire was at the height of its power. The Franks, led by Charlemagne, had built the largest European domain since Rome in its heyday. Though they jockeyed for power, prestige, and profit, the Frankish elites enjoyed political and cultural consensus. But just two generations later, their world was in shambles. Civil war, once an unthinkable threat, had erupted after Louis the Pious’s sons tried to overthrow him—and then placed their knives at the other’s neck. Families who had once charged into battle together now drew each other’s blood.

The Carolingian Civil War would rage for years as kings fought kings, brother faced off against brother, and sons challenged fathers. Oathbreakers is the dramatic history of this brutal, turbulent time. Medieval historians David M. Perry and Matthew Gabriele illuminate what happens when a once unshakeable political and cultural order breaks down and long suppressed tensions flare into deadly violence. Drawn from rich primary sources, featuring a wide cast of characters, this compelling work of narrative history rivals the greatest fictional epics—with consequences that continue to shape our own world.

Oathbreakers offers lessons of what deep cracks in a once-stable social and political fabric might reveal, and the bloody consequences of disagreeing on facts and reality. The Civil War at the heart of this tale asks: who is “in” and who is “out”? And what happens when things fall apart?

• Epic Medieval History: Based on rich primary sources, this gripping account details the collapse of the largest European domain since the Roman Empire, exploring what happens when a once-unshakeable political and cultural order breaks down.
• Family Dynasties at War: Witness the brutal, years-long conflict that pitted brother against brother and son against father, as the heirs of Louis the Pious turned on each other and drew their family’s blood in a fight for power.
• The Fall of an Empire: Discover the consequences of deep cracks in a stable social fabric, as long-suppressed tensions flare into deadly violence that ends an empire, upends a continent, and redefines the future of Europe.
• Charlemagne’s Legacy Undone: Just two generations after the legendary Charlemagne sat on the throne, his world was in shambles. This is the story of how the great Carolingian consensus fell apart at the seams.

Matthew Gabriele is a professor of medieval studies at Virginia Tech, and coauthor with David M. Perry of The Bright Ages: A New History of Medieval Europe, alongside several other academic books. His writing has appeared in numerous newspapers and magazines, and he has been featured in local, national, and international media. He and Perry co-write the newsletter Modern Medieval on Buttondown. 

David M. Perry is a journalist, a medieval historian, and the associate director of undergraduate studies in the history department at the University of Minnesota. He was formerly a professor of history at Dominican University. Perry is the author of Sacred Plunder: Venice and the Aftermath of the Fourth Crusade and coauthor of The Bright Ages: A New History of Medieval Europe. His writing has appeared in the New York Times, the Washington Post, the Nation, the Atlantic, and on CNN.com, among other outlets. He and Gabriele co-write the newsletter Modern Medieval on Buttondown.