In his famous 1960 article on ‘turbulent frontiers’, the pioneer of imperial history John Galbraith argued that the edges of British power in the nineteenth century were imbued with a magnetic quality, pulling officials towards intervention and the eventual, often unintended, expansion of territory. Although the idea that British expansion was primarily driven by unwitting ‘men on the spot’ has long been challenged, a new interest in spatial formations, imperial administration and agents on the frontier has emerged. Thomas Simpson's The Frontier in British India builds on this scholastic momentum by exploring the complexity of frontiers as messy, heterogeneous and fractured spaces best understood from the perspective of agents on the ground. This refreshing bottom-up perspective centres the idea of ‘productive difficulties’ – individual and administrative failure and opaqueness – as constitutive of the frontier itself. This perspective enables Simpson to account for governance, violence and knowledge production as simultaneously ‘spectacular and … chaotic’, ‘fragile and threatening’, ‘dramatically present and frequently ineffective’ (pp. 4–5) and capable of ‘egregious destruction and farcical ineffectiveness’ (p. 9).

Focusing on the north-east and north-west frontiers of British India through visual and written sources, Simpson dedicates each chapter to a distinct mode of colonial frontier making. A neat teleological narrative having been rejected, the reader is presented with diverse materials and agents enrolled in divergent and often incoherent projects of frontier formation. From the minutiae of individual objects like maps, to the grand discourses emanating from the metropole, the thematic approach offers a lens of frontier making at various scales. An engagement with infrastructures, such as telegraphs and railways, as modes of frontier making in their own right would have deepened this approach and provided an opportunity for connecting micro and macro agencies across the frontier.

Chapter 1, ‘Borders’, analyses the haphazard, confused and decentralized process of delineation in Assam, Punjab and Sind. In the Darrang district in Assam in 1873–4, for example, Simpson explains, the partial demarcation of the boundary did not emanate from central authority but was ‘something of an afterthought’, conducted by a survey party sent to establish a border between Bhutan and India (p. 47). Central border directives were often ‘lost in transmission’ and creatively adapted by imperial agents. By contrast, centralized attempts at strategic border creation frequently failed because they were not only removed and inimical to the terrain and livelihoods of many frontier communities, but also were contrary to the self-styled ‘heroic’ identities forged by men on the spot. Rather than executing the will of metropolitan strategists, these men engaged in subverting central administration and exacerbating confusion to maintain what they believed to be a certain kind of uncorrupted freedom and idiosyncratic power (p. 24). While the chapter's scope is broad with insights into the arbitrary construction of land borders from the ground, an engagement with maritime and coastal frontiers in the Indian Ocean would have supplemented the terrestrial focus, offering an expanded set of non-European interactions and networks into the process of imperial frontier production.

Chapter 2, ‘Surveys and maps’, looks at their increasing importance to colonial spatial sciences, while Chapter 3 analyses the emergence of frontier ethnography. By the mid-nineteenth century, the frontier had shifted in the imperial imagination from pliable and reformable to unknowable and ‘sublime’, hostile to modern scientific techniques and instruments. Rather than improved legibility, these difficulties produced a range of opportunities for further surveying and new spatial experimentations, leading to ‘diversity and dissensus’ of approaches and further scientific intrusion and interest (p. 146). Thus failures and gaps in scientific knowledge contributed to, rather than inhibiting, imperial interventions.

Chapters 4 and 5 focus on violence and administration as entangled techniques of frontier making by analysing interactions with the Balochis in Sind, the Nagas in the north-east uplands, and imperial ‘expeditions’ in the Punjab. Colonial violence, like forms of knowledge production on the frontier, also represented the limitations, as much as the strengths, of British power. In the Naga Hills, for example, violence ‘did not emanate from a position of confidence and certainty’ but was instead ‘a means of instantiating authority in situations in which officials lacked knowledge and believed that they faced major challenges’ (p. 210). Using administrative logics developed in Assam and Baluchistan, Simpson builds on Benjamin Hopkin's encompassing concept of ‘frontier governmentality’. For Simpson, frontier governmentality operated as a vague set of ambiguous logics that often failed to meet expectations rather than a singular and successful administrative technique.

Simpson concludes by examining the emergence of the ‘scientific frontier’, conceived as spaces of tension between ‘closure’ – as scientifically administered and delineated boundaries – and openness – as spaces of ‘spatial, epistemic, and administrative indeterminacy’ (p. 261). Even as India's frontiers were supposedly becoming fixed, agents continued generating and revelling in productive difficulty ‘rather than merely suffering it’ (p. 262). While Galbraith's unwitting man on the spot may be consigned to the debates of the past, Simpson has inventively and rigorously demonstrated the importance of those on the ground by introducing ‘productive difficulties’. Simpson demonstrates that agents of empire are still crucial in understanding the formation and operation of the imperial frontier.