Networks and Dynamics of Violent Political Mobilization

Historical Evidence from Spain

Giacomo Lemoli and Sergi Martínez





sergi.martinez@gess.ethz.ch | sergimartinez.github.io

Motivation

Motivation

We reached the highest number of state-based conflicts since 1946 (PRIO, 2024).

  • Syria, Ethiopia, or Colombia. Who fights?

1. Volunteers, first movers

2. Concripts

What leads volunteers to take arms?

What drives conscripts’ compliance?

Contribution

The composition of soliders changes through conflicts:

  • Volunteers and (reservists) compliers differ in their motivation (e.g., Eck 2014)

  • Our contribution: Context and network embeddedness matter differently in different contexts

Literature and theoretical expectations

What Drives Civil Conflict Participation?

Intrinsic Motivations

Extrinsic incentives: Elite-Led & Coercive

Gap: Existing scholarship treats motivations as constant, but these drivers of participation change as conflict evolves

Theoretical Argument

Phase 1, conflict onset: Intrinsic motivations dominate

Early mobilizers (hardliners) via identity and ideological networks (Staniland 2012; Sanı́n and Wood 2014; Abramson and Qiu 2024; Kalmoe 2020)

Phase 2, conflict escalation: Extrinsic motivations rise

As territorial control shifts and armies need to fill the tanks through forced recruitment (Eck 2014), survival and fear of retribution displace ideological drives (Kalyvas 2006; Rozenas, Talibova, and Zhukov 2023)

  • What drives conscripts’ compliance? Power-less proximity to elites yields adherence among non-compliers

The Spanish Civil War in Navarre

The Spanish 1930s

Spanish Civil War

1936-1939: Civil War

  • Failed fascist coup that divided the country for 39 months

  • Rebels, Francoists vs. Loyalists contenders of the Republic

  • Both sides killed and displaced civilians using indiscriminate and selective techniques

  • About 500,000-800,000 deaths

  • known as the “dress rehearsal for WWII”

Spanish Civil War

The fascist coup and the mobilization

  • July 18, 1936: Franco staged the coup.

  • In 10 days, elect. and paramilitary networks joined 10K volunteers in Pamplona.

Posterior compulsory conscription

  • August ’36, stable territorial control.

  • Both sides called for conscripts.

  • Rebels: 13 call ups on 12 cohorts (1929-1941).

Enlistments and conscript call-ups

Threat: State and society

Municipality-level evidence

Data and results: Electoral roots of rebellion

First-movers - Electoral networks (Turnout ’36 and Right-wing vote share ’36) → voluntary enlistment

Volunteers vs. conscripted

% Right-wing ’36 on voluntary enlistment

Results: Electoral roots of rebellion (not compliance)

Robust to controls and PJud. FE, (App A.1) and DiD models (App A.2)

Individual-level evidence

Data: Census and the File of Fighters

  • 34’ voting-age census, n ≈ 160,000, 1/2 males (80K over 23yo)

  • File of Navarrese fighters, n ≈ 12K>25 y/o in 1936 (71% merged) (App B)

Example: Surname network in Abaigar

One tie = Interfamily marriage


2 measures from social networks: influence and dependence

Individual data: Implications and description

Implications

  • Intrinsic incentives (social and ideological incentives) → volunteers

  • Extrinsic incentives (fear) → compliance joining later, when called-up and possibly reported

Drivers of early volunteering

\[ \Pr(\text{Volunteer}_i) = \alpha + \beta_1 \text{Age}_i + \beta_2 \text{Age}_i^2 + \beta_3 \text{Cen}_{f(i)} + \beta_4 \text{MPD}_{f(i)} + \beta_5 \ln(\text{Pop}_m) + \beta_6 \text{Carl}_{m,36} + \beta_7 \text{Right%}_{m,36} + \varepsilon_{m,i} \]

Joining voluntarily
Fam. Centrality 0.023** (0.010) 0.004 (0.008)
Fam. Proximity -0.045*** (0.013) -0.016 (0.012)
(log) Population -0.006*** (0.002)
Carlist club (pre-war) 0.012*** (0.004)
Right % '36 0.046*** (0.010)
Num.Obs. 73203 73029


  • Early mobilization occurred in right-wing, Carlist, small towns

Drivers of late joining

\[ \Pr(\text{Late joiner}_i) = \alpha + \beta_1 \ln(\text{Pop}_m) + \beta_2 \text{Carl}_m + \beta_{3} \text{Right \%}_{m,36} + \beta_4 \text{Age}_i + \beta_5 \text{Age}_i^2 + \]

\[ \beta_6 \text{Conscripted}_i + \beta_7 \text{Centrality}_{f(i)} + \beta_8 \text{MPD}_{f(i)} + \beta_{9} (\text{Cen}_{f(i)} \times \text{Cons}_i) + \beta_{10} (\text{MPD}_{f(i)} \times \text{Cons}_i) + \varepsilon_{m,i} \]

Joining late
(log) Population -0.005 (0.004) -0.005 (0.004)
Carlist club 0.011 (0.007) 0.011 (0.007)
Right % '36 -0.008 (0.023) -0.009 (0.023)
Fam. Centrality -0.026* (0.015) -0.018** (0.008)
Fam. Proximity 0.066*** (0.021) 0.020* (0.011)
Conscripted cohort 0.085*** (0.006) 0.027 (0.018)
Fam. Centrality × Conscripted -0.043 (0.043)
Fam. Proximity × Conscripted 0.191*** (0.063)
Num.Obs. 71342 71342

Conclusion

Discussion: Today


Conclusions

The interwar period backsliding was endogenous to the pre-war scenario, separately, in political and social terms:

  • Pre-war electoral networks → volunteer mobilization

  • Threat of retribution → compliance

Literature

Thanks for listening!

References

References

Abramson, Scott F, and Xiaoyan Qiu. 2024. “A Cause to Fight.” Available at SSRN.
Adena, Maja, Ruben Enikolopov, Maria Petrova, Veronica Santarosa, and Ekaterina Zhuravskaya. 2015. “Radio and the Rise of the Nazis in Prewar Germany.” The Quarterly Journal of Economics 130 (4): 1885–1939.
Arias, Eric, Pablo Balán, Horacio Larreguy, John Marshall, and Pablo Querubı́n. 2019. “Information Provision, Voter Coordination, and Electoral Accountability: Evidence from Mexican Social Networks.” American Political Science Review 113 (2): 475–98.
Arjona, Ana. 2016. Rebelocracy. Cambridge University Press.
Arjona, Ana M, and Stathis N Kalyvas. 2012. “Recruitment into Armed Groups in Colombia: A Survey of Demobilized Fighters.” Understanding Collective Political Violence, 143–71.
Atwell, Paul, and Noah L Nathan. 2022. “Channels for Influence or Maps of Behavior? A Field Experiment on Social Networks and Cooperation.” American Journal of Political Science 66 (3): 696–713.
Bai, Ying, Ruixue Jia, and Jiaojiao Yang. 2023. “Web of Power: How Elite Networks Shaped War and Politics in China.” The Quarterly Journal of Economics 138 (2): 1067–1108.
Bandiera, Antonella, Horacio Larreguy, and Jorge Mangonnet. 2026. “Family Ties, Social Control, and Authoritarian Distribution to Elites.” American Political Science Review 120 (1): 226–44.
Barber IV, Benjamin, and Charles Miller. 2019. “Propaganda and Combat Motivation: Radio Broadcasts and German Soldiers’ Performance in World War II.” World Politics 71 (3): 457–502.
Blattman, Christopher. 2023. Why We Fight: The Roots of War and the Paths to Peace. Penguin.
Cagé, Julia, Anna Dagorret, Pauline Grosjean, and Saumitra Jha. 2023. “Heroes and Villains: The Effects of Heroism on Autocratic Values and Nazi Collaboration in France.” American Economic Review 113 (7): 1888–1932.
Carozzi, Felipe, Edward Pinchbeck, and Luca Repetto. 2023. “Scars of War: The Legacy of WWI Deaths on Civic Capital and Combat Motivation.”
Caspitegui, Francisco Javier. 2005. “" Spain’s Vendee": Carlist Identity in Navarre as a Mobilising Model.” In The Splintering of Spain: Cultural History and the Spanish Civil War, 1936-1939, edited by Chris Ealham and Michael Richards. Cambridge University Press.
Costa, Dora L, and Matthew E Kahn. 2003. “Cowards and Heroes: Group Loyalty in the American Civil War.” The Quarterly Journal of Economics 118 (2): 519–48.
Cruz, Cesi, Julien Labonne, and Pablo Querubin. 2017. “Politician Family Networks and Electoral Outcomes: Evidence from the Philippines.” American Economic Review 107 (10): 3006–37.
———. 2020. “Social Network Structures and the Politics of Public Goods Provision: Evidence from the Philippines.” American Political Science Review 114 (2): 486–501.
Dippel, Christian, and Stephan Heblich. 2021. “Leadership in Social Movements: Evidence from the" Forty-Eighters" in the Civil War.” American Economic Review 111 (2): 472–505.
Dube, Oeindrila, and Juan F Vargas. 2013. “Commodity Price Shocks and Civil Conflict: Evidence from Colombia.” The Review of Economic Studies 80 (4): 1384–1421.
Eck, Kristine. 2014. “Coercion in Rebel Recruitment.” Security Studies 23 (2): 364–98.
Gates, Scott. 2017. “Membership Matters: Coerced Recruits and Rebel Allegiance.” Journal of Peace Research 54 (5): 674–86.
Hall, Andrew B, Connor Huff, and Shiro Kuriwaki. 2019. “Wealth, Slaveownership, and Fighting for the Confederacy: An Empirical Study of the American Civil War.” American Political Science Review 113 (3): 658–73.
Humphreys, Macartan, and Jeremy M Weinstein. 2008. “Who Fights? The Determinants of Participation in Civil War.” American Journal of Political Science 52 (2): 436–55.
Kalmoe, Nathan P. 2020. With Ballots and Bullets: Partisanship and Violence in the American Civil War. Cambridge University Press.
Kalyvas, Stathis N. 2006. The Logic of Violence in Civil War. Cambridge University Press.
Leira-Castiñeira, Francisco J. 2020. “El Terror Represivo y El Reclutamiento Forzoso Del Ejército Golpista. El Caso de Galicia, 1936-1939.” Hispania Nova: Revista de Historia Contemporánea 18: 203–32.
Leira-Castiñeira, Francisco J, and Andrés Domı́nguez-Almansa. 2018. “Reclutados Para Ganar. Movilización y Respuesta de Los Soldados de Franco.” Ayer. Revista de Historia Contemporánea 111 (3): 79–107.
Lyall, Jason, and Yuri Zhukov. 2021. “Fratricidal Coercion in Modern War.” Available at SSRN 3956923.
Rego, Maria Aurora Artiaga. 2014. “Movilización Rebelde En El Verano de 1936: Galicia,?‘ Una Nueva Covadonga?” In Otras Miradas Sobre Golpe, Guerra y Dictadura: Historia Para Un Pasado Incómodo, 111–49. Los Libros de la Catarata.
Rogall, Thorsten. 2021. “Mobilizing the Masses for Genocide.” American Economic Review 111 (1): 41–72.
Rozenas, Arturas, Roya Talibova, and Yuri Zhukov. 2023. “Fighting for Tyranny: State Repression and Combat Motivation.” Working Paper.
Sanı́n, Francisco Gutiérrez, and Elisabeth Jean Wood. 2014. “Ideology in Civil War: Instrumental Adoption and Beyond.” Journal of Peace Research 51 (2): 213–26.
Satyanath, Shanker, Nico Voigtländer, and Hans-Joachim Voth. 2017. “Bowling for Fascism: Social Capital and the Rise of the Nazi Party.” Journal of Political Economy 125 (2): 478–526.
Staniland, Paul. 2012. “Organizing Insurgency: Networks, Resources, and Rebellion in South Asia.” International Security 37 (1): 142–77.
Straus, Scott. 2007. “What Is the Relationship Between Hate Radio and Violence? Rethinking Rwanda’s ‘Radio Machete’.” Politics & Society 35 (4): 609–37.
Yanagizawa-Drott, David. 2014. “Propaganda and Conflict: Evidence from the Rwandan Genocide.” The Quarterly Journal of Economics 129 (4): 1947–94.

Appendix

Appendix A.1: Electoral networks of rebellion

If electoral-patronage networks mobilized right-wing hardliners as first movers:

  • Right % ’36 to predict the share of first movers.

  • Turnout ’36 to predict the share of first movers.

\(ShareVolunteers_{m} = \beta_1 ShareRight_{1936,m} + \beta_2 Turnout_{1936,m} + X_{cp} \gamma + \varepsilon_{m}\)

Volunteers July'36 Placebo w/post-Aug '36
* p < 0.1, ** p < 0.05, *** p < 0.01
% Right 1936 0.132*** -0.120**
(0.033) (0.050)
% Turnout 1936 0.097** -0.000
(0.044) (0.042)
Num.Obs. 255 255
R2 0.500 0.195

Appendix A.2: DiD

Appendix A.3: DiD

Appendix B: Matching examples

Random sample of matched insurgent–census pairs
Insurgent record
Census record
Municipality S1 (ins.) S2 (ins.) Name (ins.) Age (ins.) S1 (cen.) S2 (cen.) Name (cen.) Age (cen.)
Lumbier Caminos Irabarren Javier 30 Caminos Iribarren Javier 27
Garralda Larraz Sánchez Ambrosio 29 Larruiz Sánchez Ambrosio 24
Yerri Unanua Ilzarbe Teofanes 26 Unanua Ilzarbe Teogenes 23
Sanguesa Galarza Maestu Javier 30 Galarza Maestre Javier 25
Falces Mendoza Antón Gregorio 26 Mendoza Antón Gregorio 23
Araiz Goicoechea Loiti Fermin 27 Goicoechea Loidi Fermin 25
Arruazu Arratibel Bergara Pedro 28 Arratibel Vergara Pedro 25
Villava Echepare Ibañez Fermin 29 Echapare Ibáñez Fermin 27
Lumbier Machinandiarena Torrea Jose 27 Machinandiarena Torrero Jose 25
Tafalla Urian Reta Juan 27 Uríen Reta Juan 24
Aranguren Zabalza Giménez Tomas 26 Zabalza Jiménez Tomas 23
Estella Aramendía Garialde Joaquin 44 Aramendía Garlalde Joaquin 40
Peralta Lorea García Julian 43 Lorca García Julian 40
Ulzama Larrainzar Vallanueva Juan 29 Larrainzar Villanueva Juan 23
Estella Nuin Mendoza Herminio 29 Nuin Mendoza Herminio 23

Matches are approximate: surnames and given names may differ slightly across sources due to transcription variation, dialectal spelling, and OCR error. Age gap ≤ 10 years. Non-within-municipality matches < 3.5%.