The upheavals of World War II prepared a new labour regime in twentieth-century India, in employers’ chambers, government offices, and in the newly established Labour Department, but as crucially, at the workplace and on the shop floor. This article studies the case of Calcutta port, an important military port in Southeast Asia after the fall of Singapore and Rangoon, where the complex historical processes resulting from the war generated an unprecedented impetus for the transformation of the labour regime. It examines the powerful impact and dynamics of the war at two levels: at the level of long-run changes in the work organization, and, through a microhistory approach, at the level of workers’ everyday wartime experiences. Under wartime exigencies, the employers introduced ad hoc, piecemeal, but significant reforms – food rations, bonuses, higher wages, housing provisions, and regularization of employment – that were more extensive than originally conceived of and proved to be irreversible, and, ultimately, cracked open a labour regime based on casual labour. The focus on workers’ experiences shows us how the measures designed for stabilization and efficiency proved to be profoundly unsettling in the context of dramatic events that pervaded the workplace. In the shadows of the war, workers and employers experienced a balance of forces in flux. Labour relations were marked by anticipations, hostility, tensions, and, increasingly, sharpness of conflict. The article argues that, by the end of the 1940s, the employers and the state had overcome an industrial relations crisis through nothing less than a restructuring of port labour relations, creating a highly regulated “formal sector” with significant welfare provisions.