Chapter 2 brings the reader back to Grosse Île between 1942 and 1946, narrating the decision to create the vaccine and to share it freely once the war was over. This chapter not only introduces the technology at the heart of the story, but also shows how that technology encouraged officials to think differently about international relations. The vaccines were useful against all strains of rinderpest and were easily transportable. They were not threatening. In fact, their global distribution promised only to help, not to harm the nations that had paid for their creation. Although paving the way for the globally focused actions that unfold in chapters 3 and 4, chapter 2 ends with the warning note that not all of the scientific research undertaken on Grosse Île was shared. Offensive research remained hidden, highlighting the point, which will be developed in chapter 5, that internationalist thinking had to contend with national security concerns in the postwar era. The vaccines, which emphasized global environmental interdependence, opened the door to new pursuits along both lines.