Drought, locust invasion, and epidemic disease struck Algeria between 1866 and 1868. These environmental crises became the largest human disaster in Algerian history, killing 800,000 people and reshaping political and social relationships. This disaster was a result not only of environmental and climatic phenomena, but also of the socio-economic disruptions brought about by nearly four decades of colonialism. Processes of state formation that began in the first decades of colonial rule achieved a new intensity and coherence during this disastrous period. The disaster engendered a reorganization of power in Algeria: settlers and both the military and civilian administrations were united for the first time around the need for state intervention. What we see in this situation is the convergence of environmental disaster and settler colonialism as disaster brought the need for new methods of governance, new institutions to undertake this governance, and new discourses to justify or explain them. This dissertation argues that drought, locusts, cholera, typhus, earthquakes, crop-destroying hail, flooding, and the devastating human cost of these events, provoked changes in the organization of power in Algeria. That is, the power to physically coerce people, to monitor their behavior and enforce norms, and set the agenda of how institutions like the military and civil administrations delegated resources took on a different organization during the disaster. The environmental disaster of the 1860s provoked changes to the administration of cities, the countryside, and the people located therein; involved more people, institutions, and discourses in the network of existing power relationships; and created new centers of power and new ways of relating to those centers within the colony. The environmental disaster reorganized power relationships in Algeria in a way that, for the first time, evoked a modern colonial state.