Terrorist, rebel, and insurgent groups are highly unstable. Amid fears of defeat and even death, intense disagreements have torn many organizations apart, from Syria to Iraq, Ireland to Spain. And while some of these divisions have preceded a group’s decline and eventual defeat, others have launched some of the most notorious and deadly organizations in recent history.


In Divided not Conquered, Evan Perkoski analyzes how armed groups fracture and how breakaway splinter groups behave. Perkoski takes an unprecedented look inside these organizations to understand the specific disagreements that cause groups to break apart, like those over ideology, leadership, and strategy. Drawing on research from organizational studies to social psychology, and leveraging analogies from business firms to religious sects, Perkoski shows how these disputes uniquely shape the behavior and survivability of emerging splinters. When motivated by single, shared disagreements, splinters exhibit higher cohesion, clearer objectives, and greater survivability. When motivated by strategy, splinters attract hardline operatives who steer the group towards increasingly lethal tactics and strategies. 


Including case studies of republican militants in Northern Ireland, Basque militants in Spain, and the Islamic State in Syria and Iraq, Divided not Conquered demystifies a complex yet common phenomenon with ramifications for counterinsurgency, counterterrorism, and our understanding of increasingly fragmented conflicts around the globe.

Available for purchase at Amazon, Bookshop, and directly from Oxford University Press

“Evan Perkoski has delivered an impressive study of why militant group fragmentation can produce such profoundly different patterns of violence. His answer is novel, rigorous, and elegant—how and why the splinter groups break away determines how they behave in their next incarnation. A truly fascinating and persuasive read.”

—Erica Chenoweth, Harvard University 


“This well-conceived analysis, buttressed by careful use of evidence, answers vexing questions about the fragmentation of militant organizations that are of interest to both scholars and policymakers. Perkoski links the formation of splinter groups to their subsequent behavior and undermines the commonly held assumption that offshoots are more radical than the original group.”

—Martha Crenshaw, Stanford University and Wesleyan University 


“An admirably systematic exploration of the intra-organizational dynamics of terrorism. Original, serious-minded, and fascinating.”

—Richard English, author of Does Terrorism Work? A History