In this well-written and impressively researched new book, Eric Grynaviski explores how the United States was able to recruit nonstate allies to help support its foreign policy aims. He highlights the important role played by “intermediaries” (p. 2), individuals who live in between societies and can exploit their local knowledge and monopoly on information to temper mistrust and conflicts of interest. The result is a narrative of international politics that does not focus on “great men” sitting in capital cities but rather on the missionaries, traders, soldiers, and adventurers who through a combination of social skill and political savvy were able to have a dramatic and unexpected influence on events.

This book is filled with both theoretical and empirical innovations. Grynaviski borrows from social network theory to examine what he calls the “power of betweenness” (p. 28). When societies lack dense social connections with one another, individuals who reside between them can take advantage of these “structural holes” to gain disproportionate influence (p. 21). Their language skills, cultural understanding, and access to diverse sources of information make them uniquely situated to broker cooperation (pp. 38–44). Grynaviski illustrates this process through a series of detailed case studies that examine the recruitment of nonstate allies during the Revolutionary, Barbary, and the American Civil Wars, as well as the conquests of Samoa and the Philippines. These case studies, which are based on extensive qualitative historical research across multiple archives, are a genuine achievement. They delve deep into the micro-dynamics of frontier politics, highlighting how a motley collection of grifters, schemers, and true believers came to play an outsized role in the evolution of U.S. foreign policy.

Grynaviski is not the first scholar to highlight the unexpected power of these kinds of actors. He notes growing interest in the comparative history of “borderlands” and the role that “cultural brokers” can play in such liminal spaces (pp. 36–37, 284–85). He alludes to but does not extensively cite the voluminous literature on the role of traders, missionaries, and political agents in expansion and governance of colonial empires (for some recent examples, see Colin Newbury, Patrons, Clients, and Empire: Chieftaincy and Over-Rule in Asia, Africa, and the Pacific, 2003; Richard Price, Making Empire: Colonial Encounters and the Creation of Imperial Rule in Nineteenth-Century Africa, 2008; John Darwin, The Empire Project: The Rise and Fall of the British World System, 1830–1970, 2009; Jane Burbank and Frederick Cooper, Empires in World History: Power and the Politics of Difference, 2010; and citations in Paul K. MacDonald, Networks of Domination: The Social Foundations of Peripheral Conquest in International Politics, 2014; pp. 52–56, 240–41, 255–57). Yet Grynaviski’s book challenges conventional accounts of international politics in a number of profound ways. It highlights that foreign policy is made not only by principals in the core but also by agents in the periphery. It illustrates that the power of individual actors flows not just from their formal institutional positions but also from their informal personal connections. It demonstrates that global politics is shaped not simply by the actions of states but also by their entanglements with nonstate actors.

Although Grynaviski’s archival research is impeccable, I had questions about the scope of his theory and how well the empirical evidence mapped onto some of his key concepts. First, the theory makes some assumptions about actors’ preferences that do not always hold in practice. The state and its potential nonstate allies, for example, are assumed to have shared interests that an intermediary can help explain to the respective parties (pp. 40–41). Yet in some cases, interests are so opposed that even the most well-positioned intermediary cannot bridge them. Indeed, intermediaries caught between clashing societies can be in a particularly perilous position, as missionaries often were when preaching alongside land-hungry settlers. Along the same lines, intermediaries are assumed to have strong incentives to help forge cooperation, either for personal or professional gain (pp. 52–54). Yet sometimes they have incentives to limit cooperation between local actors and external patrons. Missionaries might fear that their parishioners will be exploited by settlers or state agents, or traders might be worried about losing their favored position under some new commercial arrangement. Because Grynaviski focuses on successful cases, we do not know how often intermediaries failed to produce cooperation, either because structural holes were too wide or because they refused to play the role of bridge builders.

Second, the theory assumes that the primary benefit that intermediaries provide is their ability to overcome information and ideational barriers to potential cooperation: they can help identify potential partners, explain common interests, build trust, and overcome cultural conflicts (pp. 54–55). Yet in some cases, nonstate actors seem swayed more by material opportunities than the broader information environment. In Samoa, for example, the plantation owner H. J. Moors developed a close relationship with Mata’afa not because of his deep cultural understanding, but because he was supplying Mata’afa’s rebels with food and guns (p. 169). In other cases, nonstate actors appear to have shifted loyalties in response to local threats. The Oneidas opted to side with the Americans during the Revolutionary War as part of an effort to “displace” the Mohawks in the Iroquois Confederacy (p. 80). The Pawnee decision to cooperate with the North during the U.S. Civil War was shaped by their “deep enmity” for the Sioux (p. 130). The Macabebe were willing to join with the Americans in the Philippine War because they had been “plundered” by insurgents (p. 234). These examples suggest that nonstate actors are not simply the cat’s paws of foreign intermediaries, but make decisions to collaborate or resist based on a complex array of local considerations.

Third, the theory portrays the ideal-typical intermediary as a skilled free agent who has “only weak ties with their own government” (p. 29) and does “not consider themselves delegates of a principal” (p. 31). It is this independence that allows intermediaries to exploit their language skills, bicultural identities, and personal reputations to transcend social divides (pp. 33–38). Yet in practice, many of the intermediaries Grynaviski discusses were direct agents of the American government who had just met their potential partners and whose success depended less on cultural brokerage than on their willingness to oversell American promises. For example, during the Barbary War, William Eton, the U.S. consul to Tunis, persuaded Ahmed to revolt by promising him the throne (p. 104). In Samoa, Albert Steinberger, President Grant’s special agent, secured the support of local insurgents by pretending to support Samoan land claims (p. 157). In the Philippines, Spencer Pratt, the U.S. consul of Singapore, convinced Aguinaldo to rebel by suggesting that Washington endorsed Philippine independence (pp. 204, 214). The picture is less one of skilled cultural navigators than unconstrained government agents willing to lie and cheat to accomplish their aims, whether cooperative or conflictual.

These questions aside, Grynaviski provides a welcome critique of state- and leader-centric accounts of international politics. His case studies persuasively demonstrate that U.S. foreign policy is driven as much by intermediaries and frontier politics as by metropolitan officials and their policies.