Early-Life Origins of Wartime Behaviour: The Irish Potato Famine and Desertion in the American Civil War

• Published date: 01 February 2025
• DOI: http://doi.org/10.1177/00104140241237461
• Author: Dylan Potts
• Date: 01 February 2025

Article

Comparative Political Studies

2025, Vol. 58(2) 291–326

© The Author(s) 2024

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DOI: 10.1177/00104140241237461

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Early-Life Origins of

Wartime Behaviour: The

Irish Potato Famine and

Desertion in the

American Civil War

Dylan Potts

1



Abstract

How does pre-war trauma impact battlef‌ield behaviour? I study Irish troops in

the American Civil War who experienced the Potato Famine over a decade

prior. I use birth cohorts, sibling birth order, adult height, and the geography

of last names in Ireland to measure famine exposure within the Irish group at

the level of individual soldiers. Each strategy indicates that famine exposure

increases desertion. Developing and testing observable implications from

theory, I show that heightened risk aversion is the most plausible mechanism.

Once soldiers are socialized into active combat through collective risk-sharing

the famine effect dissipates. This research contributes to our understanding of

the causes of contentious behaviour, how the behavioural legacies of

atrocities play-out sans partisanship, and the importance of pre-migration

experiences.

Keywords

civil war, conf‌lict processes, migration, military and politics, political economy

1

European University Institute, Fiesole, Italy

Corresponding Author:

Dylan Potts, Department of Political and Social Sciences, European University Institute, Via della

Badia dei Roccettini 9, Fiesole 50014, Italy.

Email: dylan.potts@eui.eu

Data Availability Statement included at the end of the article

Why people participate in violence is a core question in understanding human

behaviour (Kalyvas, 2006;Levi, 1997). Indeed, understanding the cohesion of

soldiers in wartime has received extensive attention from social scientists due

to its importance for wartime outcomes and the subsequent long-run de-

velopment of societies at micro and macro levels (Besley & Persson, 2008;

Lyall, 2020;Scheve & Stasavage, 2010;Shils & Janowitz, 1948). Expla-

nations of soldiers’behaviour, and the choice to f‌ight on or desert, have paid

attention to their proximate groups (Bearman, 1991;Costa & Kahn, 2010), the

home front’s politics or geography (Kalmoe, 2020;McLauchlin, 2014),

economic incentives (Berman et al., 2011;Humphreys & Weinstein, 2008),

coercion (Gates, 2002), and the armed group’s socialization process (Cohen,

2013;Gates, 2017;Gilligan et al., 2023). I argue that individuals’experiences

before war also exerts effects on their performance during service. In par-

ticular, I propose that experiences suffered before a conf‌lict’s onset have

behavioural effects during war. Beyond the dynamics of groups, ideology, and

identity, experiences in the pre-war lives of soldiers also play a role in de-

termining behaviour.

I study how the potato famine impacted service among Irish-Americans in

the US Civil War. I f‌irst measure famine through birth cohorts with the

identifying assumption that experiencing famine at a younger age has rela-

tively larger effects. I show that younger Irish soldiers, born just before

famine, desert at higher rates. I develop this approach comparing siblings who

served together and show that only for Irish troops birth order is a signif‌icant

predictor of desertion. This within-family analysis reduces confounders across

birth cohorts. I also leverage a measurement strategy exploiting how soldiers’

adult heights are only affected by malnutrition when they are at a certain stage

of childhood. When height proxies malnutrition shorter soldiers desert more

frequently in the Irish group. Lastly, I map soldiers to their potential origins in

Ireland using the geographical spread of last names. I f‌ind that Irish soldiers

whose names originate from areas with higher population loss and greater

famine relief desert more.

Studying famine and wartime service in a setting where the conf‌lict is

divorced from the original trauma which allows for theory generation distinct

from preferences or partisanship. From this theory I draw and test observable

implications of two potential channels; risk-aversion and re-traumatization.

Through supplementary empirical testing and a case-study of two New York

regiments I f‌ind that additional Irish desertion is concentrated in the f‌irst weeks

of service. Irish soldiers are akin to Germans once each group has been

deployed and participated in active combat. When Irish soldiers are socialized

on the battlef‌ield through collective risk sharing the famine effect is no longer

discernible and thus these empirical patterns are consistent with a risk-

aversion stemming from famine. I test several alternative mechanisms such

292 Comparative Political Studies 58(2)

as economics, identity, discrimination, physical weakness and different roles

in the military to rule out these pathways.

This research speaks to how traumatic events shape behaviour (Bauer et al.,

2016;Blattman, 2009), the causes of wartime micro-level patterns (Ager et al.,

2021), and how migrants’new lives, and the societies they join, can be shaped

by experiences before arrival (Dippel & Heblich, 2021). I add to our un-

derstanding of the American Civil War but also speak to a potentially broader

literature of wars in the aftermath of famine and repression (Rozenas et al.,

2022;Rozenas & Zhukov, 2019). Famine in the modern world typically co-

occurs with violent conf‌lict, so studying the relationship between these events

enriches our understanding. A f‌inal contribution of this work is to disentangle

traumatic events from preferences. I study victims of famine f‌ighting in a war

disconnected from the root cause of their prior suffering. In this way, I can

probe mechanisms beyond the partisan preferences which would overwhelm

other mechanisms if the war was against those responsible for go verning the

famine (Henn and Huff 2021;Narciso & Severgnini, 2023).

The Irish in the American Civil War

An initial, proximate cause of the food shortage was the infestation of the

potato crop upon which Ireland depended (Mokyr, 2013). Over time, a

weakened, malnourished population was assaulted by waves of fever which

amplif‌ied the death toll against a backdrop of a distant landed elite class of

land owners, restrictive relief policies and continued food exports during the

hunger (Anbinder, 2001;Mokyr, 2013;Ravallion, 1987;Walker, 2007). The

combined process of mass starvation and movement meant the island of

Ireland today has fewer inhabitants than in 1840 before the famine. More than

two million people left Ireland to seek refuge during the famine (Boyle &

Gr´

ado, 1986;Gr´

ada, 2020). Emigration was the optimal way to survive due to

the abysmal relief efforts deployed by the UK government and led to large

chunks of the Irish populace re-locating to the United States (Grada &

O’Rourke, 1997). The trans-Atlantic passage offered a ‘safety valve’for

Irish during the famine and then initiated chains of migration, often for young

adults seeking employment in the post-famine landscape (Fitzpatrick, 1980).

Irish movement to the United States had begun long before the famine but

the rate rose markedly from 1845 when the potato crop f‌irst failed, and during

the 1840s Irish communities blossomed in the industrializing cities of New

England and the Midwest (Anbinder & McCaffrey, 2015). Through the

famine years, over 500,000 Irish settled in the US and this episode of mi-

gration, un-impinged by government restrictions on arrivals, was also typif‌ied

by relatively poorer entrants vis-a-vis other groups and the earlier Irish

(Collins & Zimran, 2019;Ferenczi & Willcox, 1929). Irish arrivals met

hostility from the native population, facing discrimination in their daily

Potts 293