Global urbanization has given rise to the megacity: large, densely-packed urban areas with more than ten million people. These cities are becoming increasingly connected, dense and complex, and are becoming non-state actors’ preferred hiding places. It is inevitable that the US military will find the need to operate in this environment, and it is currently unprepared to do so. Gaining and maintaining a comprehensive understanding of the environment is the first challenge to preparing forces for megacity urban operations. The emerging fields of big data, analytics, and data-driven decision-making offer significant potential towards this end. The Army must study this environment and the emerging sets of tools if it wishes to remain relevant in tomorrow’s fight.