Command over the U.S. Armed Forces is established in the Constitution. The sole power of command is vested in the President by Article II as Commander-in-Chief. The Constitution presumes the existence of "executive Departments" headed by "principal officers", whose appointment mechanism is provided for in the Appointments Clause. This allowance in the Constitution formed the basis for creation of the Department of Defense in 1947 by the National Security Act. The DoD is headed by the Secretary of Defense, who is a civilian and member of the Cabinet. The Defense Secretary is second in the U.S. Armed Forces chain of command, with the exception of the Coast Guard, which is under the Secretary of Homeland Security, and is just below the President and serves as the principal assistant to the President in all defense-related matters. Together, the President and the Secretary of Defense comprise the National Command Authority, which by law is the ultimate lawful source of military orders.
In Medieval Europe, tales of knighthood and chivalry, the officer class of the period captured the popular imagination. Writers and poets like Taliesin, Chrétien de Troyes and Thomas Malory wrote tales of derring-do, featuring Arthur, Guinevere, Lancelot and Galahad. Even in the 21st century, books and films about the Arthurian legend and the Holy Grail continue to appear.
The primary reason for the existence of the military is to engage in combat, should it be required to do so by the national defence policy, and to win. This represents an organisational goal of any military, and the primary focus for military thought through military history. How victory is achieved, and what shape it assumes, is studied by most, if not all, military groups on three levels.
The U.S. Armed Forces are one of the largest militaries in terms of the number of personnel. It draws its personnel from a large pool of paid volunteers. Although conscription has been used in the past in various times of both war and peace, it has not been used since 1972, but the Selective Service System retains the power to conscript males, and requires that all male citizens and residents residing in the U.S. between the ages of 18–25 register with the service.
Additionally, all services except for the Air Force have an active warrant officer corps. Above the rank of warrant Officer One, these officers may also be commissioned, but usually serve in a more technical and specialized role within units. More recently, they can also serve in more traditional leadership roles associated with the more recognizable officer corps. With one notable exception (Army helicopter and fixed-wing pilots), these officers ordinarily have already been in the military often serving in senior NCO positions in the field in which they later serve as a warrant officer as a technical expert. Most Army pilots have served some enlisted time. It is also possible to enlist, complete basic training, go directly to the Warrant Officer Candidate School at Fort Rucker, Alabama and then on to flight school.
Standard Scores are scores that have a fixed mean and standard deviation in the population of examinees. A Standard Score indicates how many units of the standard deviation a particular score is above or below the mean. In the case of the ASVAB subtests, the mean is set to 50 and the standard deviation is set to 10. Thus, a Standard Score of 40 indicates that the examinee scored 1 standard deviation below the mean. A Standard Score of 70 indicates that the examinee scored 2 standard deviations above the mean. To learn more about how standard scores are derived and used, click here.