Jasen J. Castillo

This report defines and describes will to fight and provides a model of unit will to fight that can be applied to ground combat units of any scale. The model provides a research-grounded template for case-by-case adviser assessment of partner or allied military forces and the intelligence analysis of adversary forces. This report also provides a theoretical basis for adding will to fight to military war gaming and simulation.

Scholars and military practitioners alike have long sought to understand why some country's militaries fight hard when facing defeat while others collapse. In Endurance and War, Jasen Castillo presents a new unifying theory—cohesion theory—to explain why national militaries differ in their staying power. His argument builds on insights from the literatures on group solidarity in general and military effectiveness in particular, which argue that the stronger the ties binding together individuals in a group of any kind, the higher the degree of cohesion that a group will exhibit when taking collective action, including fighting in war. Specifically, he argues that two types of ties determine the cohesion, and therefore the resilience, of a nation's armed forces during war: the degree of control a regime holds over its citizens and the amount of autonomy the armed forces possess to focus on training for warfighting. Understanding why armed forces differ in their cohesion should help U. S. military planners better assess the military capabilities of potential adversaries, like Iran and North Korea. For scholars of international politics, cohesion theory can help provide insights into how countries create military power and how they win wars.

This report presents a framework for assessing U. S. Army International Activities (AIA). It also provides a matrix of eight AIA ends, derived from top-level national and Army guidance, and eight AIA ways, which summarize the various capabilities inherent in AIA programs. In addition, the report describes the new online AIA Knowledge Sharing System (AIAKSS) that is being used to solicit programmatic and assessment data from AIA officials in the Army's Major Commands.