The 1902 court case Jacobson v. Massachusetts marks a moment in U.S. history in which the imperial state explicitly makes the field of life itself as a proper domain of governmental intervention. Responding to fears that settler colonialism brought an expanding United States into dangerous intimacies with contagions from Asian and Caribbean frontiers of imperial expansion, U.S. health and military officials increasingly intervened in the entanglement of viruses, bacteria, animals, and humans. Racialized fears of contact were increasingly marshaled to produce new forms of optimism in technology and large-scale vital systems, making the neoliberal immune system a key node in the national defense. This channeling of fear into optimism in state technologies of control—dread life—unleashed new practices of decolonization by turning medical knowledges, treatment protocols, patient collectives, social space, and the migrations of humans and animals into sites of struggle with the security state.