Blood and Concrete: 21st Century Conflict in Urban Centers and Megacities provides a foundation for understanding urban operations and sustaining urban warfare research. This Small Wars Journal (SWJ) Anthology documents over a decade of writings on urban conflict. In addition to essays originally published at SWJ it adds new content including an introduction by the editors, a preface on “Blood and Concrete” by David Kilcullen, a foreword "Urban Warfare Studies" by John Spencer, a postscript “Cities in the Crossfire: The Rise of Urban Violence” by Margarita Konaev, and an afterword “Urban Operations: Meeting Challenges, Seizing Opportunities, Improving the Approach” by Russell W. Glenn. These essays frame the discussion found in the collection’s remaining 49 chapters. Blood and Concrete continues the legacy of Small Was Journal's coverage of urban operations, conflict and combat. The more than 50 chapters written by some 80 authors in this comprehensive Small Wars Journal anthology examine a significant threat: the increasing prevalence of urban centers as primary areas of military operations, surpassing rural areas in conflict regions around the world. As pointed out by David Kilcullen in his excellent preface, since it is impossible to mention all the volume's contributors, some of the issues raised by their chapters include the challenges for militaries in engaging in urban centers' physical and "cyber" terrains, and the employment of new technologies, such as drones, to conduct warfare against insurgent adversaries in such environments. Another challenge is presented by General Charles Krulak, a former Marine Corps Commandant, who is cited in John Spencer's foreword as stating that the future of urban warfare will consist of a "three-block war" where military forces "are simultaneously required to conduct humanitarian assistance on one block, peace-keeping on the other, and traditional warfighting the next over" (p. xli). In their introduction, the editors insightfully point out that "Differentiating between the tactical, operational, and strategic concerns accompanying each of these distinct (and sometimes converging) conurbations is essential to understanding and preparing for urban operations" (p. xlix). In the postscript, Margarita Konaev makes the important point that one of the reasons for the prevalence of urban warfare is that it is increasingly difficult for insurgents to operate in rural environments because "emerging technologies, and advances in surveillance techniques and aerial detection capabilities have also made the classic rural guerilla warfare settings of dense jungles and remote mountain hideouts far less safe for violent non-state groups. In cities, however, these militants can more easily blend into the local civilian population and use the city's complex and dense terrain for cover and concealment" (p. 648). Ms. Konaev's conclusion well sums up the volume's important contribution to the literature on counterterrorism and counterinsurgency: "as the world's urban population continues to grow, the future of global security will be determined by what happens in cities" (p. 651). -- Joshua Sinai, Perspectives on Terrorism , February 2019. Warfare has become an urban phenomenon. Conflicts, political violence, and war will most likely occur in urban megacities rather than rural areas (xli). I recommend Blood and Concrete: 21st Century Conflict in Urban Centers and Megacities to students and future leaders at the US Army. -- Dr. José de Arimatéia da Cruz, US Army War College Review: Parameters , Fall 2021. Blood and Concrete: A Small Wars Journal Anthology is essential reading for practitioners and scholars of modern war and security. -- Michael L. Burgoyne , Journal of Strategic Security, Vol. 16, no. 2 (2023). Dave Dilegge is Editor-in-Chief of Small Wars Journal. Dr. Robert J. Bunker is an Adjunct Research Professor, Strategic Studies Institute, U.S. Army War College, Carlisle, PA and a Senior Fellow with Small Wars Journal—El Centro. Dr. John P. Sullivan served as a Lieutenant with the Los Angeles Sheriff’s Department and is a Senior Fellow with Small Wars Journal—El Centro. Dr. Alma Keshavarz is a Small Wars Journal—El Centro Associate. She received her PhD in Political Science from Claremont Graduate University.