Major McCulloh and Major Johnson wrote this monograph on hybrid warfare while they were students at the School of Advanced Military Studies, Fort Leavenworth, Kansas. Written in two parts, their individual approaches complement each other by providing a synergistic combination of both an overarching theory as well as an operational perspective. While the idea of hybrid warfare is not new, the authors together provide a clarity and utility which presents a relevant contextual narrative of the space between conventional conflicts and realm of irregular warfare. Major McCulloh's contribution in the first section lays the theoretical basis to bring a definition of hybrid warfare into focus while addressing the pertinent question of its historical origin. Major Johnson's section uses historical examples and case studies to form a basis for approaching hybrid threats through a lens of U.S. oriented operational art. The authors contribute to the understanding of warfare as a spectrum of conflict rather than a dichotomy of black and white alternatives.