Daniel Byman is a Professor at Georgetown University's School of Foreign Service and a Senior Fellow at the Center for Middle East Policy at the Brookings Institution. He is the author of A High Price, The Five Front War, and Al Qaeda, The Islamic State, and the Global Jihadist Movement: What Everyone Needs to Know.

"a high-quality, monograph that includes a solid number of sources and references." -- Georgi Asatryan, Insight Turkey

"...fascinating... Byman tells the stories of some well-known and a few not so well-known foreign fighters to show how the system evolved over the decades, through several cycles of mobilization." -- Jytte Klausen, Bustan: The Middle East Book Review

"Byman sits at the top of everybody's shortlist of preeminent scholar/teachers on terrorism and counterterrorism. He has produced a book that will prove every bit as valuable to senior policymakers and practitioners as it will be to generations of scholars and students. Road Warriors is carefully researched and documented and yet it still reads like a first-rate novel as it traces the intellectual and physical journey traveled by this latest generation of jihadist fighters." -- Nicholas J. Rasmussen, Former Director of the National Counterterrorism Center

"Foreign fighters from Osama bin Laden to the ISIS 'Beatles' are force multipliers who have contributed to making jihadist conflicts more ideological and more violent. In this major work of synthesis, Byman elucidates a myriad of sources to create the best account we have of the foreign fighter phenomenon over the past half century." -- Peter Bergen, author of United States of Jihad: Investigating America's Homegrown Terrorists

"Byman's unique study of the phenomenon of foreign fighters is the prism through which he provides a thorough and fascinating story of the origins and evolution of both al Qaeda and the most important jihadist battlefields over the course of the last thirty-plus years." -- Mitchell D. Silber, Former Director of Intelligence Analysis, New York Police Department

"In nearly every conflict in which I've been involved, foreign fighters have played a significant and dangerous role. These disparate groups and individuals have grown to be a permanent fixture of modern extremist movements, and are tied irrevocably to unresolved sources of radicalization, the power of jihadi narratives, the emergence of social media, and the ease of international travel. Byman has captured all of this in one book, which I wish had been available to other commanders and me a generation ago as America first began to grapple with the horrific reality of global terrorism. He has done us all a great service, and I commend this excellent book in the strongest possible terms." -- John R. Allen, former Special Presidential Envoy to the Global Coalition to Counter ISIL; General, US Marine Corps (Ret.), and President, The Brookings Institution