America kicked off the twenty-first century with a two-decade losing streak. In Iraq and Afghanistan, the United States failed to understand the societies in which it was fighting. Blind to local fundamentals, the US military proved unable to achieve effects via futuristic technology and lethal force; at the same time, civilian-led development and governance initiatives delivered a negligible return on a staggering investment. How should the US military understand the current geopolitical environment? What are the essential capabilities to succeed therein? Cutting against the grain of contemporary military thought-which focuses overwhelmingly on so-called "near-peer" competitors and the technologies needed to confront them-this book argues for the importance of understanding the playing field of strategic competition. Bringing together the collective experience and expertise of nineteen soldiers, marines, and scholar-practitioners, this book draws upon the lessons of recent past to chart a contrarian view for the future. The book begins with a survey of the current geopolitical landscape, observing the global resonance of ostensibly local issues within a fragmenting international order. It then explores the features of the "gray zone" between peace and war, highlighting the importance of ground truth and focused contextual understanding. Discussions in the book address doctrinal shortcomings with respect to the concept of the "human domain" and the consequences thereof vis-à-vis the military's understanding of influence and non-kinetic operations. Focus then shifts to the warrior diplomats themselves, examining how Civil Affairs forces approach the critical discipline of civil reconnaissance-alongside a detailed examination of the inadequacy of current investigative frameworks and the presentation of a potential alternative. A case study is then presented, detailing the work of warrior diplomats in the Sahel, followed by discussion of pressing issues and ongoing changes within the US Army's and US Marine Corps' Civil Affairs capabilities. Finally, the book examines complementarities between US Civil Affairs and the Civil-Military Cooperation (CIMIC) forces fielded by allies worldwide as well as the potential for further collaboration and interoperability. With a formidable blend of real-world experience and academic rigor, this book illuminates the importance of the warrior diplomat within the US military-and the need to invest in and strengthen capabilities in the human domain. Observing the limitations of technology in the provision of causal understanding, this book puts humans front and center in the military's approach to understanding and action in the human domain. Warrior Diplomats is a valuable resource for military personnel, leaders across the defense and intelligence communities, and strategists who plan military operations and campaigns. It also will be useful to academic researchers, students, and general readers interested in strategy, foreign policy, applied social science, and the US military. *This book is in the Rapid Communications in Conflict and Security (RCCS) Series (General Editor: Geoffrey R.H. Burn)