Upon entry into WWII, the United States committed to unconditional victory through overwhelming force. But paramount focus on material capacity to the neglect of “will to fight” in subsequent regional wars—Vietnam, Iraq, and Afghanistan—has carried woeful costs in lives, treasure, and policy failures. This nearly happened with Ukraine. Despite political and military leaders acknowledging its importance after the fact, consensus remains that will to fight is “imponderable.” Without rigorously assessing nonmaterial sensibilities, including among civilian populations, conflict can appear intractable or only resolvable with massive force, and the United States and partners may continue to overrate or underrate allies, armies, and peoples in disregard of the spirit that can only arise from one’s own cultural identity and values.