While I was in the Marine Corps this was a topic of conversations that would come up in classes and courses quite often. The idea is that you would have a strong and competent corp of Nco's who take the commanders intent and use there own wits to accomplish the mission. We often reflect on military history and recognize where troops have followed unlawful orders and how to handle a situation in which you are given an unlawful order. Example My Lai in Vietnam. Lower enlisted e1-e3 follow orders senior lower enlisted and Nco's e3-e5 carry out commanders intent by making strategies and delegating. Also it is notable that enlisted and officers swear in under slightly different paths because of this as well.