All of the branches work together during operations and joint missions in Unified Combatant Commands, under the authority of the Secretary of Defense with the typical exception of the Coast Guard. Each of the Unified Combatant Commands is headed by a Combatant Commander, a senior commissioned officer who exercises supreme command authority per 10 U.S.C. § 164 over all of the forces, regardless of branch, within his geographical or functional command. By statute, the chain of command flows from the President to the Secretary of Defense to each of the Combatant Commanders.[22] In practice, the Chairman of the Joint Chiefs of Staff often acts as an intermediary between the Secretary of Defense and the Combatant Commanders.

The rapid growth of movable type in the late 16th century and early 17th century saw an upsurge in private publication. Political pamphlets became popular, often lampooning military leaders for political purposes. A pamphlet directed against Prince Rupert of the Rhine is a typical example. During the 19th century, irreverence towards authority was at its height, and for every elegant military gentleman painted by the master-portraitists of the European courts, for example, Gainsborough, Goya, and Reynolds, there are the sometimes affectionate and sometimes savage caricatures of Rowland and Hogarth.

In the 2000s, women can serve on U.S. combat ships, including in command roles. They are permitted to serve on submarines.[39] Women can fly military aircraft and make up 2% of all pilots in the U.S. Military. In 2003, Major Kim Campbell was awarded the Distinguished Flying Cross for landing her combat damaged A-10 Thunderbolt II with no hydraulic control and only one functional engine after being struck by hostile fire over Baghdad.

Each of the five services employs a single Senior Enlisted Advisor at departmental level. This individual is the highest ranking enlisted member within that respective service and functions as the chief advisor to the service secretary, service chief and Congress on matters concerning the enlisted force. These individuals carry responsibilities and protocol requirements equivalent to three-star general or flag officers. They are as follows:

The AFQT has been used in non-military settings as a proxy measure of intelligence, for example, in Herrnstein & Murray's book The Bell Curve. Because of the test's significance both inside and outside military settings, it is important to examine what the test measures, i.e. to evaluate the construct validity of the AFQT. Kaufman's 2010 review stated that David Marks (2010) scanned the literature for datasets containing test estimates for populations or groups taking both the AFQT and tests of literacy. One study on nine groups of soldiers differing in job and reading ability found a correlation of .96 between the AFQT and reading achievement (Sticht, Caylor, Kern, & Fox, 1972). Another study showed significant improvements among Black and Hispanic populations in their AFQT scores between 1980 and 1992 while Whites only showed a slight decrement (Kilburn, Hanser, & Klerman, 1998). Another study obtained reading scores for 17-year olds for those same ethnic groups and dates (Campbell et al., 2000) and found a correlation of .997 between reading scores and AFQT scores. This nearly perfect correlation was based on six pairs of data points from six independent population samples evaluated by two separate groups of investigators. According to Marks, "On the basis of the studies summarized here, there can be little doubt that the Armed Forces Qualifications Test is a measure of literacy." However, it is important to note that AFQT has been shown to correlate more highly with classic IQ tests than they do with one another, and that the "crystallized" intelligence measured by AFQT is measured very similarly by Wechsler, in particular.[8]
One set of ASVAB scores – Career Exploration Scores – tells you your current strengths in verbal, math, science, and technical skills.  The scores allow you to compare your test performance with that of other students at your grade level and can help you determine your readiness for further education and training in different career areas.  You will also receive a Military Entrance Score that is important for entry into the Armed Services.  You can discuss your score with a military recruiter.
The ASVAB is a population-referenced exam, which means that the score you receive for the ASVAB is not an exact measure of how you scored on the test, but rather how you scored in relation to a national control group who took the test in 1997. Standard Scores are used on the ASVAB: in each subtest, about 50% of the population received a Standard Score of 50, while only 16% scored over 60. You will receive an estimated score after taking the paper test and official scores later through your recruiter, usually within days. You will immediately receive your scores upon completing the computer test.

The AFQT is often mistakenly called the “overall ASVAB score.” You commonly hear someone say, “I got a 67 on the ASVAB,” or “My ASVAB score was 92.” That’s not correct; it implies that the AFQT is derived from all nine subtests of the ASVAB, and it’s not. The AFQT score is computed from just four of the ASVAB subtests that measure your math and communicative ability.

Military tactics concerns itself with the methods for engaging and defeating the enemy in direct combat. Military tactics are usually used by units over hours or days, and are focused on the specific, close proximity tasks and objectives of squadrons, companies, battalions, regiments, brigades, and divisions, and their naval and air force equivalents.[31]

Initially, recruits without higher education or college degrees will hold the pay grade of E-1 and will be elevated to E-2 usually soon after basic training. Different services have different incentive programs for enlistees, such as higher initial ranks for college credit, being an Eagle Scout and referring friends who go on to enlist as well. Participation in DEP is one way recruits can achieve rank before their departure to basic training.
Personnel may be recruited or conscripted, depending on the system chosen by the state. Most military personnel are males; the minority proportion of female personnel varyies internationally (approximately 3% in India,[8] 10% in the UK,[9] 13% in Sweden,[10] 16% in the US,[11] and 27% in South Africa[12]). While two-thirds of states now recruit or conscript only adults, as of 2017 50 states still relied partly on children under the age of 18 (usually aged 16 or 17) to staff their armed forces.[13]
Examinees also receive a score on what is called the Armed Forces Qualification Test (AFQT). AFQT scores are computed using the Standard Scores from four ASVAB subtests: Arithmetic Reasoning (AR), Mathematics Knowledge (MK), Paragraph Comprehension (PC), and Word Knowledge (WK). AFQT scores are reported as percentiles between 1-99. An AFQT percentile score indicates the percentage of examinees in a reference group that scored at or below that particular score. For current AFQT scores, the reference group is a sample of 18 to 23 year old youth who took the ASVAB as part of a national norming study conducted in 1997. Thus, an AFQT score of 90 indicates that the examinee scored as well as or better than 90% of the nationally-representative sample of 18 to 23 year old youth. An AFQT score of 50 indicates that the examinee scored as well as or better than 50% of the nationally-representative sample.
After adopting the test in 1976 the test became a way of indicating whether or not an individual was 100% qualified to serve. As previously mentioned this aptitude test has a colorful history. That is because it underwent a dramatic change in 2002 and another dramatic change in 2004. The change that occurred in 2002 expanded the categories of the test and the overall difficulty. This can be seen by the addition of all of the diverse categories below: