Chapter 3 lays out the methods and the logic of case selection that underpin the book. This book is a theory-building and theory-probing undertaking—I build a theory of how the alternative benefits of bargaining lead combatants to seek out UN peacekeeper while probing how the credible commitment theory of war termination drives the desire for peace operations—and process tracing using a most-similar cases approach is one way to do this.In this chapter, I outline first the method by which I selected cases, building a catalogue of the UN’s peacekeeping successes and failures, and a timeline of what peacekeeping successes and failures combatants would have seen around the world as they were negotiating, in order to do so, and then discuss the evidence and tools I use to process-trace the Rwandan and Guatemalan peace processes. Readers who are interested primarily in the substance of the text and not in methodological discussion, or a discussion of multiple archives, can proceed to the subsequent three chapters without reading Chapter 3.

This chapter evaluates the UN’s engagement in Guatemalan negotiations from 1989-1996. It asks how the Government of Guatemala (the GoG) and the Unidad Revolucionaria Nacional Guatemalteca (URNG), the coalition of rebel groups fighting and negotiating with the GoG, assessed the UN’s performance as the guarantor of agreements elsewhere, especially the concurrent peacekeeping success in neighboring El Salvador and the simultaneous failure in the Balkans, and how these assessments influenced the course of negotiations and the final agreement that emerged from their peace process. Drawing on archival material and oral histories, I find that participants looked nearly exclusively at El Salvador to assess the contours and possibilities of UN intervention—but they perceived the Salvadoran example as a negative one: both sides believed their Salvadoran counterparts had given too much away during their negotiations, and advocated for a smaller UN mission.This is surprising—influential credible commitment theories of peacekeeping predict that the UN’s success in El Salvador would enhance the Guatemalan parties’ confidence in the UN as guarantor. Instead, the UN’s banner success in El Salvador first prolonged the war in Guatemala and then produced a weaker agreement and a degraded capacity to enforce the peace.