Abstract The dominant approach to war and state-building attributes state development to wartime growth of extractive capacity. Yet we know little about the administrative foundation through which extractive capacity is increased spatially, beyond the central policy level. Using railways as an example of a state-building asset, I revisit the role of external threat on state-building, with evidence drawing upon detailed historical data from nineteenth-century India during a crucial period of Anglo–Russo rivalry. I find that conflict with Russia led to expansion of railways in the Northwest Frontier bordering Afghanistan, the buffer between British India and Russia, which led to improved performance of local tax administrators. The findings suggest that external conflict promotes state development through provision of logistical networks enabling greater administrative efficiency in geographically distant frontiers.