What can explain the decline in incumbent victory in counterinsurgency wars? Political scientists offer a variety of explanations for these trends. Some focus on the structure and doctrine of counterinsurgent forces, while others emphasize the lethality and motivation of insurgent adversaries. I challenge these explanations. Declines in incumbent victory in counterinsurgency wars are not driven by fundamental shifts in the character of these conflicts, but in the political context in which they take place. Nineteenth-century colonial incumbents enjoyed a variety of political advantages—including strong political will, a permissive international environment, access to local collaborators, and flexibility to pick their battles—which granted them the time and resources necessary to meet insurgent challenges. In contrast, twentieth-century colonial incumbents struggled in the face of apathetic publics, hostile superpowers, vanishing collaborators, and constrained options. The decline in incumbent victory in counterinsurgency warfare, therefore, stems not from problems in force structure or strategy, but in political shifts in the profitability and legitimacy of colonial forms of governance.