According to Roberto Esposito, modernity is marked by an immunitary logic in which defending against contagion is a central preoccupation. To immunize is to seek the negative protection of life; it is intended to safeguard life through the introduction of the pathogen from which protection is sought. Though immunization is normally associated with the health sciences, for Esposito it is constitutive of the entanglement of biology and politics.1 One aspect of this interconnection was insightfully investigated by Susan Sontag in her exploration of the medical discourses surrounding disease. Concerns about the spread of syphilis and tuberculosis during and at the close of the First World War led to public education campaigns in which disease was cast as an invasion of the body. At this time, metaphors became a credible and precise means of conceptualizing disease.2 Though it was in her initial analysis of the discourse surrounding cancer that Sontag discovered the military metaphor, she later ruminated that infectious disease - the prime modern example being HIV/AIDS, which is said to come from outside, to hide within cells and to elude detection - is the example par excellence of the militaristic framing of disease.3 Indeed, it is the permanent vulnerability to infection from an outside agent that renders infectious disease permissible to a violent imaginary involving a struggle to the death, a battle, a war. Yet just as disease is fantasized as an enemy and its treatment a fight, the inverse is also apparent: in some instances warfare is articulated though the lexicon of medicine and therapy. Some forms of warfare cast the enemy as a disease of the social body against which protection can be procured. This essay considers the interconnection between biology and politics by examining how, in military thought, the metaphors of infectious disease and its treatment and prevention - culminating in the paradigm of immunity, as Esposito calls it - are deployed to characterize insurgency and its remedy.To claim that war is articulated through lexicon of medicine and therapy is counter to the reasonable view that war is a destructive battle to the death. Yet, although war is always destructive, almost all wars of today are not only rationalized on humanitarian grounds but call for the integration of humanitarian means into the struggle at hand. In recent years new counterinsurgency doctrines have emerged among the U.S., UK, and Canadian militaries that claim such credentials. Though building on lessons of the past, twenty-first-century counterinsurgency is a unique entity. As the form of conflict it confronts is said to be hybrid in character, involving the convergence of combatants and noncombatants, kinetic and nonkinetic, physical and psychological weaponry - it proposes a similarly hybrid model of warfare that calls on military and civilian expertise, governmental and nongovernmental organizations, that form a wide network of contemporary internationalism. Indeed, a key marker of contemporary counterinsurgency is its incorporation of the aspirations and techniques of mainstream international development and humanitarianism into the battlespace of war.4 Unlike the general thrust of conventional warfare which promises, rather straightforwardly, an economy of fatality and destruction, modern counterinsurgency evinces an elaborate politics of life. Though death lingers in the corpus of counterinsurgency, it posits an ideal of its own which emphasizes the betterment of the population in whose midst it is exercised. Thus the use of medical discourse in counterinsurgency is formative in articulating a politics of life and regeneration, amid the death and destruction that accompanies war.The characteristics of modern counterinsurgency add to the increasingly prominent role of the life sciences in shaping the politics of international security. Interdisciplinary, international research has begun to explore the ways in which security is being redefined as a medical problem and deepening connections between the psychiatric sciences and modes of warfare. …