Probably one of the most succinct and best essays that provides the rationale for why we should study military history.
The entire essay can be accessed at the link below or downloaded in PDF at this link: http://www.fpri.org/docs/society_for_mil_hist_whit_paper.pdf
Though the study of war is demanding, both intellectually and emotionally, we cannot afford to eschew or ignore it. Examining the origins of wars informs us about human behavior: the way that we create notions of identity, nationality, and territoriality; the way that we process and filter information; and the way that we elevate fear and aggression over reason. Analyzing the nature of war informs us about the psychology of humans under stress: the patterns of communication and miscommunication within and across groups; the causes of escalation; and the dynamics of political and social behavior within nations and across populations. And studying the consequences of wars helps us to understand human resilience, resignation, and resentment; we learn to identify unresolved issues that may lead to further strife, and we develop a heightened ability for comprehending the elements of political behavior that can lead to sustainable resolution and the re-building of broken—indeed sometimes shattered—social, political, and economic structures and relationships.