In his comprehensive study, , sociologist Anthony King explores how the fundamental nature of military cohesion has shifted from social bonding to professional competence. By analyzing Western infantry platoons from World War I to the war in Afghanistan, King argues that modern combat is a "social activity" defined more by collective virtuosity in drills than by the interpersonal "social cohesion" of the past. The Evolution of Military Cohesion

King distinguishes between two primary forms of cohesion that have defined different eras of warfare: