This chapter explores the intersection of international relations theory and history by applying Robert Jervis’ framework from Perception and Misperception in International Relations to the controversial leadership of Field Marshal Bernard “Monty” Montgomery during the closing campaigns of World War II. While international relations scholars and historians often operate in isolation from one another—each critical of the other’s methodologies—Jervis’ insights offer a valuable bridge between these disciplines. Historians have thoroughly examined Monty’s actions and biases, yet integrating Jervis’ theories provides a deeper understanding of how perception, misperception, and inherent bias shaped his strategic decisions under stress. Personal ambition, competition for resources, and the overarching allied goal of ending the war influenced Monty’s leadership, which fluctuated between caution and aggression. By applying Jervis’ framework, this study highlights how cognitive biases impact senior leader decision-making in complex and competitive environments, contributing to broader discussions on strategy and leadership analysis.