Somewhat earlier, in medieval China, gunpowder had been invented, and was increasingly used by the military in combat. The use of gunpowder in the early vase-like mortars in Europe, and advanced versions of the long bow and cross bow, which all had armour-piercing arrowheads, that put an end to the dominance of the armoured knight. After the long bow, which required great skill and strength to use, the next most significant technological advance was the musket, which could be used effectively, with little training. In time, the successors to muskets and cannon, in the form of rifles and artillery, would become core battlefield technology.
The ASVAB test is administered to potential military recruits to help determine which branch of service and which military jobs they will be best suited for. It is not a test of intelligence and is administered only in English. The test consists of nine subjects: General Science, Arithmetic Reasoning, Word Knowledge, Paragraph Comprehension, Mathematics Knowledge, Electronics Information, Auto and Shop Information, Mechanical Comprehension, and Assembling Objects.
AFQT scores are the primary measure of recruit potential. Figure 2.7 indicates the percentage of NPS recruits who scored at or above the 50th percentile (Categories I–IIIA) since FY 1973. Numerical data are in Appendix D, Table D-12. The drop in Category I–IIIA recruits after FY 1976 was due primarily to the miscalibration of the ASVAB.  In FY 1976, when new versions of the ASVAB were introduced, an error in calibrating the score scales made the new versions "easier" than the old versions (i.e., applicants received test scores higher than their actual ability). In FY 1980, an independent study of the calibration was made and the test was correctly calibrated. Then, Congress added legal provisions stipulating that no more than 20 percent of accessions could be in Category IV and that such accessions had to be high school diploma graduates.  However, as previously stated, Defense Planning Guidance decreases this limit even further, allowing no more than 4 percent of recruits to come from Category IV.
The Armed Services Vocational Aptitude Battery is more commonly known as the ASVAB Test. If you are interested in a military career, you will need to pass this challenging test in order to qualify. It is used for all branches of the military which includes the Army, Navy, Air Force, Marines, National Guard, and Coast Guard. It is also used to gauge your abilities in specific areas that may be relevant to your job assignments within the military. For more information about the exact details of this exam, check out our article titled What is the ASVAB Test?
The paper-and-pencil version of the test administered at a Mobile Examination Test (MET) site usually takes 3–4 hours. The time needed to take the CAT-ASVAB test can vary. The test is adaptive. If the candidates answer a question correctly, they are given one of increasing difficulty. If the candidates miss a question, they are subsequently given an easier item. This pattern continues until the test is finished. Because of its adaptive nature, the CAT-ASVAB test generally takes about half the time of the paper-and-pencil version.
Development of military doctrine is perhaps the more important of all capability development activities, because it determines how military forces were, and are used in conflicts, the concepts and methods used by the command to employ appropriately military skilled, armed and equipped personnel in achievement of the tangible goals and objectives of the war, campaign, battle, engagement, action or a duel. The line between strategy and tactics is not easily blurred, although deciding which is being discussed had sometimes been a matter of personal judgement by some commentators, and military historians. The use of forces at the level of organisation between strategic and tactical is called operational mobility.
In the 2000s, women can serve on U.S. combat ships, including in command roles. They are permitted to serve on submarines. 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.