Image by Patrick Fore

Research and Publications

My article and book projects interrogate fundamental assertions in International Relations scholarship about the nature of national military power.

Gurkhas in the Malayan jungle, c.1941

Legionnaires: Why States Recruit Foreign Soldiers

My book project explains the calculus that has led modern states to recruit soldiers who are neither subjects nor citizens of the government they serve—foreign legionnaires. The book beings by presenting an original dataset of recruitment policies, identifying legionnaire enlistment programs that states have implemented between 1815 and 2020. Drawing on government records in multiple languages, I show how these policies have influenced modern history’s major wars and spanned the globe.

The project details and tests a theory that explains how governments select among this fuller spectrum of manpower options. I argue that the selection of recruitment policies—citizen or legionnaire—is a function of how a state perceives its vulnerability to defeat, as shaped by two variables: the severity of external threats that it perceives, and the degree to which the government faces political costs in mobilizing additional citizen soldiers. I use archival evidence to present four case studies that test my argument across the full range of its independent and dependent variable values: Angola (1974-76), Germany (1935-45), India (1962-64), and the United States (1861-64).

Free French Legion soldiers in Libya, c.1942

Introducing the Foreign Recruitment Dataset:
Legionnaires and the Spectrum of Military Manpower

This article introduces the foreign recruitment dataset, documenting how governments have supplemented their citizen-based armies with legionnaires—individuals who are neither citizens, colonial subjects, or co-ethnics of the government that they serve. Contrary to the expectations of existing political science research, the recruitment of legionnaires has been both an enduring and an expanding feature of how governments build their military power. 

This project details historical trends in how governments have enlisted foreigners in the modern age (1815 - 2020), including the growth of these policies over time, the methods states have adopted in fielding these troops, the types of regimes that have enlisted legionnaires, and patterns of naturalization. The article closes by outlining research questions where the addition of this data can add unique insight, and identifies the implications for ongoing scholarly debates.

World War II battle lines

Leaning on Legionnaires:
Why Modern States Recruit Foreign Soldiers

*Forthcoming - International Security 

Why do modern states recruit legionnaires—foreigners who are neither citizens nor subjects of the country whose military they serve? Rather than exclusively enlist citizens for soldiers, for the past two centuries, states have mobilized legionnaires to help wage offensives, project power abroad, and suppress dissent. A supply-and-demand argument explains why states recruit these troops, framing the choice to mobilize legionnaires as a function of political factors that constrain the government’s leeway to recruit domestically and its perceptions about the territorial threats it faces externally. A multimethod approach evaluates these claims, first by examining an original dataset of legionnaire recruitment from 1815 to 2020, then by employing congruence tests across World War II participants, and finally by conducting a detailed review of a hard test case for the argument—Nazi Germany. The prevalence of states’ recruitment of legionnaires calls for a reevaluation of existing narratives about the development of modern militaries and provides new insights into how states balance among the competing imperatives of identity, norms, and security. Legionnaire recruitment also underscores the need to recalibrate existing methods of calculating net assessments and preparing for strategic surprise. Far from bound to a state’s citizenry or borders, the theory and evidence show how governments use legionnaires to buttress their military power and to engineer rapid changes in the quality and quantity of the soldiers that they field.

Read More