Once the hub of Norwegian defence planning, the Norwegian operational level plays a less significant role today. The operational level is the link between the strategic and tactical levels, adapting political and strategic ends to feasible plans and operations. This study looks at various questions regarding the development of the operational level. How were the key institutions built up? And which events made them less significant? Traditionally, these questions have been addressed mainly by using technological or political science approaches. By adding social theory to the perspectives the author also highlights the importance of civil-military relations and popular political support as a base of legitimacy for building and maintaining military institutions. Although the study looks at a development specific to Norway, it also describes an international trend experienced by a number of military organisations.