Ancient Egypt was a civilization of ancient North Africa, concentrated along the lower reaches of the Nile River in the place, now the country Egypt. Ancient Egyptian civilization followed prehistoric Egypt and coalesced around 3100 BC with the political unification of Upper and Lower Egypt under Menes; the history of ancient Egypt occurred as a series of stable kingdoms, separated by periods of relative instability known as Intermediate Periods: the Old Kingdom of the Early Bronze Age, the Middle Kingdom of the Middle Bronze Age and the New Kingdom of the Late Bronze Age. Egypt reached the pinnacle of its power in the New Kingdom, ruling much of Nubia and a sizable portion of the Near East, after which it entered a period of slow decline. During the course of its history Egypt was invaded or conquered by a number of foreign powers, including the Hyksos, the Libyans, the Nubians, the Assyrians, the Achaemenid Persians, the Macedonians under the command of Alexander the Great; the Greek Ptolemaic Kingdom, formed in the aftermath of Alexander's death, ruled Egypt until 30 BC, under Cleopatra, it fell to the Roman Empire and became a Roman province.
The success of ancient Egyptian civilization came from its ability to adapt to the conditions of the Nile River valley for agriculture. The predictable flooding and controlled irrigation of the fertile valley produced surplus crops, which supported a more dense population, social development and culture. With resources to spare, the administration sponsored mineral exploitation of the valley and surrounding desert regions, the early development of an independent writing system, the organization of collective construction and agricultural projects, trade with surrounding regions, a military intended to assert Egyptian dominance. Motivating and organizing these activities was a bureaucracy of elite scribes, religious leaders, administrators under the control of a pharaoh, who ensured the cooperation and unity of the Egyptian people in the context of an elaborate system of religious beliefs; the many achievements of the ancient Egyptians include the quarrying and construction techniques that supported the building of monumental pyramids and obelisks.
Ancient Egypt has left a lasting legacy. Its art and architecture were copied, its antiquities carried off to far corners of the world, its monumental ruins have inspired the imaginations of writers for centuries. A new-found respect for antiquities and excavations in the early modern period by Europeans and Egyptians led to the scientific investigation of Egyptian civilization and a greater appreciation of its cultural legacy; the Nile has been the lifeline of its region for much of human history. The fertile floodplain of the Nile gave humans the opportunity to develop a settled agricultural economy and a more sophisticated, centralized society that became a cornerstone in the history of human civilization. Nomadic modern human hunter-gatherers began living in the Nile valley through the end of the Middle Pleistocene some 120,000 years ago. By the late Paleolithic period, the arid climate of Northern Africa became hot and dry, forcing the populations of the area to concentrate along the river region.
In Predynastic and Early Dynastic times, the Egyptian climate was much less arid. Large regions of Egypt were traversed by herds of grazing ungulates. Foliage and fauna were far more prolific in all environs and the Nile region supported large populations of waterfowl. Hunting would have been common for Egyptians, this is the period when many animals were first domesticated. By about 5500 BC, small tribes living in the Nile valley had developed into a series of cultures demonstrating firm control of agriculture and animal husbandry, identifiable by their pottery and personal items, such as combs and beads; the largest of these early cultures in upper Egypt was the Badari, which originated in the Western Desert. The Badari was followed by the Amratian and Gerzeh cultures, which brought a number of technological improvements; as early as the Naqada I Period, predynastic Egyptians imported obsidian from Ethiopia, used to shape blades and other objects from flakes. In Naqada II times, early evidence exists of contact with the Near East Canaan and the Byblos coast.
Over a period of about 1,000 years, the Naqada culture developed from a few small farming communities into a powerful civilization whose leaders were in complete control of the people and resources of the Nile valley. Establishing a power center at Nekhen, at Abydos, Naqada III leaders expanded their control of Egypt northwards along the Nile, they traded with Nubia to the south, the oases of the western desert to the west, the cultures of the eastern Mediterranean and Near East to the east, initiating a period of Egypt-Mesopotamia relations. The Naqada culture manufactured a diverse selection of material goods, reflective of the increasing power and wealth of the elite, as well as societal personal-use items, which included combs, small statuary, painted pottery, high quality decorative stone vases, cosmetic palettes, jewelry made of gold and ivory, they developed a ceramic glaze known as faience, used well into the Roman Per
True range multilateration
True range multilateration is a method to determine the location of a movable vehicle or stationary point in space using multiple ranges between the vehicle/point and multiple spatially separated locations. True range multilateration is both a mathematical topic and an applied technique used in several fields. A practical application involving a fixed location is the trilateration method of surveying. Applications involving vehicle location are termed navigation when on-board persons/equipment are informed of its location, are termed surveillance when off-vehicle entities are informed of the vehicle's location. Two slant-ranges from two known locations can be used to locate a third point in a two-dimensional Cartesian space, a applied technique. Two spherical ranges can be used to locate a point on a sphere, a fundamental concept of the ancient discipline of celestial navigation—termed the altitude intercept problem. Moreover, if more than the minimum number of ranges are available, it is good practice to utilize those as well.
This article addresses the general issue of position determination using multiple ranges. In two-dimensional geometry, it is known that if a point lies on two circles the circle centers and the two radii provide sufficient information to narrow the possible locations down to two – one of, the desired solution and the other is an ambiguous solution. Additional information narrow the possibilities down to a unique location. In three-dimensional geometry, when it is known that a point lies on the surfaces of three spheres the centers of the three spheres along with their radii provide sufficient information to narrow the possible locations down to no more than two. True range multilateration can be contrasted to the more encountered multilateration, which employs range differences to locate a point. Pseudo range multilateration is always implemented by measuring times-of-arrival of energy waves. True range multilateration can be contrasted to triangulation, which involves the measurement of angles.
Multiple, sometimes overlapping and conflicting terms are employed for similar concepts – e.g. multilateration without modification has been used for aviation systems employing both true ranges and pseudo ranges. Moreover, different fields of endeavor may employ different terms. In geometry, trilateration is defined as the process of determining absolute or relative locations of points by measurement of distances, using the geometry of circles, spheres or triangles. In surveying, trilateration is a specific technique; the term true range multilateration is accurate and unambiguous. Authors have used the terms range-range and rho-rho multilateration for this concept. Navigation and surveillance systems involve vehicles and require that a government entity or other organization deploy multiple stations that employ a form of radio technology; the advantages and disadvantages of employing true range multilateration for such a system are shown in the following table. True range multilateration is contrasted with multilateration, as both require multiple stations.
Requirements on user equipage is the most important factor in limiting true range multilateration use for vehicle navigation and surveillance. Some uses are not the original purpose for system deployment – e.g. DME/DME aircraft navigation. For similar ranges and measurement errors, a navigation and surveillance system based on true range multilateration provide service to a larger 2-D area or 3-D volume than systems based on pseudo range multilateration. However, it is more difficult or costly to measure true ranges than it is to measure pseudo ranges. For distances up to a few miles and fixed locations, true range can be measured manually; this has been done in surveying for several thousand years using chains. For longer distances and/or moving vehicles, a radio/radar system is needed; this technology was first developed circa 1940 in conjunction with radar. Since three methods have been employed: Two-way range measurement, one party active – This is the method used by radars to determine the range of a non-cooperative target, now used by laser rangefinders.
Its major limitations are that: the target does not identify itself, in a multiple target siguation, mis-assignment of a return can occur. Two-way range measurement, both parties active – This method was first used for navigation by the Y-Gerät aircraft guidance system fielded in 1941 by the Luftwaffe, it is now used globally in air traffic control – e.g. secondary radar surveillance and DME/DME navigation. It requires that both parties have both transmitters and receivers, may require that interference issues be addressed. One-way range measurement – The time of flight of electromagnetic energy between multiple stations and the vehicle is measured based on transmission by one party and reception by the other; this is the most developed method, was enabled by the development of atomic clocks. It has been demonstrated with Loran-C and GPS
Stereopsis is a term, most used to refer to the perception of depth and 3-dimensional structure obtained on the basis of visual information deriving from two eyes by individuals with developed binocular vision. Because the eyes of humans, many animals, are located at different lateral positions on the head, binocular vision results in two different images projected to the retinas of the eyes; the differences are in the relative horizontal position of objects in the two images. These positional differences are referred to as horizontal disparities or, more binocular disparities. Disparities are processed in the visual cortex of the brain to yield depth perception. While binocular disparities are present when viewing a real 3-dimensional scene with two eyes, they can be simulated by artificially presenting two different images separately to each eye using a method called stereoscopy; the perception of depth in such cases is referred to as "stereoscopic depth". The perception of depth and 3-dimensional structure is, possible with information visible from one eye alone, such as differences in object size and motion parallax, though the impression of depth in these cases is not as vivid as that obtained from binocular disparities.
Therefore, the term stereopsis can refer to the unique impression of depth associated with binocular vision. It has been suggested that the impression of "real" separation in depth is linked to the precision with which depth is derived, that a conscious awareness of this precision – perceived as an impression of interactability and realness – may help guide the planning of motor action. There are two distinct aspects to stereopsis: coarse stereopsis and fine stereopsis, provide depth information of different degree of spatial and temporal precision. Coarse stereopsis appears to be used to judge stereoscopic motion in the periphery, it provides the sense of being immersed in one's surroundings and is therefore sometimes referred to as qualitative stereopsis. Coarse stereopsis is important for orientation in space while moving, for example when descending a flight of stairs. Fine stereopsis is based on static differences, it allows the individual to determine the depth of objects in the central visual area and is therefore called quantitative stereopsis.
It is measured in random-dot tests. Fine stereopsis is important for fine-motor tasks such as threading a needle; the stereopsis which an individual can achieve is limited by the level of visual acuity of the poorer eye. In particular, patients who have comparatively lower visual acuity tend to need larger spatial frequencies to be present in the input images, else they cannot achieve stereopsis. Fine stereopsis requires both eyes to have a good visual acuity in order to detect small spatial differences, is disrupted by early visual deprivation. There are indications that in the course of the development of the visual system in infants, coarse stereopsis may develop before fine stereopsis and that coarse stereopsis guides the vergence movements which are needed in order for fine stereopsis to develop in a subsequent stage. Furthermore, there are indications that coarse stereopsis is the mechanism that keeps the two eyes aligned after strabismus surgery, it has been suggested to distinguish between two different types of stereoscopic depth perception: static depth perception and motion-in-depth perception.
Some individuals who have strabismus and show no depth perception using static stereotests do perceive motion in depth when tested using dynamic random dot stereograms. One study found the combination of motion stereopsis and no static stereopsis to be present only in exotropes, not in esotropes. There are strong indications that the stereoscopic mechanism consists of at least two perceptual mechanisms three. Coarse and fine stereopsis are processed by two different physiological subsystems, with a coarse stereopsis being derived from diplopic stimuli and yielding only a vague impression of depth magnitude. Coarse stereopsis appears to be associated with the magno pathway which processes low spatial frequency disparities and motion, fine stereopsis with the parvo pathway which processes high spatial frequency disparities; the coarse stereoscopic system seems to be able to provide residual binocular depth information in some individuals who lack fine stereopsis. Individuals have been found to integrate the various stimuli, for example stereoscopic cues and motion occlusion, in different ways.
How the brain combines the different cues – including stereo, vergence angle and monocular cues – for sensing motion in depth and 3D object position is an area of active research in vision science and neighboring disciplines. Not everyone has the same ability to see using stereopsis. One study shows that 97.3% are able to distinguish depth at horizontal disparities of 2.3 minutes of arc or smaller, at least 80% could distinguish depth at horizontal differences of 30 seconds of arc. Stereopsis has a positive impact on exercising practical tasks such
Noel Joseph Terence Montgomery Needham was a British biochemist and sinologist known for his scientific research and writing on the history of Chinese science and technology. He was elected a fellow of the Royal Society in 1941, a fellow of the British Academy in 1971. In 1992, Queen Elizabeth II conferred on him the Companionship of Honour, the Royal Society noted he was the only living person to hold these three titles. Needham was the only child of a London family, his father was a doctor, his mother, Alicia Adelaïde, née Montgomery, was a music composer from Oldcastle, Co. Meath, Ireland. Needham was educated at Oundle School before attending Gonville and Caius College, where he graduated BA in 1921, MA in January 1925, DPhil in October 1925, he had intended to study medicine, but came under the influence of Frederick Hopkins, resulting in his switch to biochemistry. After graduation, he was elected to a fellowship at Gonville and Caius College and worked in Hopkins' laboratory at the University Department of Biochemistry, specialising in embryology and morphogenesis.
His three-volume work Chemical Embryology, published in 1931, includes a history of embryology from Egyptian times up to the early 19th century, including quotations in most European languages. His Terry Lecture of 1936 was published by Cambridge University Press in association with Yale University Press under the title of Order and Life. In 1939 he produced a massive work on morphogenesis that a Harvard reviewer claimed "will go down in the history of science as Joseph Needham's magnum opus," little knowing what would come later. Although his career as biochemist and an academic was well established, his career developed in unanticipated directions during and after World War II. Three Chinese scientists came to Cambridge for graduate study in 1937: Lu Gwei-djen, Wang Ying-lai and Shen Shih-Chang. Lu, daughter of a Nanjing pharmacist, taught Needham Chinese, igniting his interest in China's ancient technological and scientific past, he pursued, mastered, the study of Classical Chinese with Gustav Haloun.
Under the Royal Society's direction, Needham was the director of the Sino-British Science Co-operation Office in Chongqing from 1942 to 1946. During this time he made several long journeys through war-torn China and many smaller ones, visiting scientific and educational establishments and obtaining for them much needed supplies, his longest trip in late 1943 ended in far west in Gansu at the caves in Dunhuang at the end of the Great Wall where the earliest dated printed book - a copy of the Diamond Sutra - was found. The other long trip reached Fuzhou on the east coast, returning across the Xiang River just two days before the Japanese blew up the bridge at Hengyang and cut off that part of China. In 1944 he visited Yunnan in an attempt to reach the Burmese border. Everywhere he went he purchased and was given old historical and scientific books which he shipped back to Britain through diplomatic channels, they were to form the foundation of his research. He got to know Zhou Enlai and met numerous Chinese scholars, including the painter Wu Zuoren, the meteorologist Zhu Kezhen, who sent crates of books to him in Cambridge, including 2,000 volumes of the Gujin Tushu Jicheng encyclopaedia, a comprehensive record of China's past.
On his return to Europe, he was asked by Julian Huxley to become the first head of the Natural Sciences Section of UNESCO in Paris, France. In fact it was Needham who insisted that science should be included in the organisation's mandate at an earlier planning meeting. After two years in which the suspicions of the Americans over scientific co-operation with communists intensified, Needham resigned in 1948 and returned to Gonville and Caius College, where he resumed his fellowship and his rooms, which were soon filled with his books, he devoted his energy to the history of Chinese science until his retirement in 1990 though he continued to teach some biochemistry until 1966. Needham's reputation recovered from the Korean affair such that by 1959 he was elected as president of the fellows of Caius College and in 1965 he became Master of the College, a post which he held until he was 76. In 1948, Needham proposed a project to the Cambridge University Press for a book on Science and Civilisation in China.
Within weeks of being accepted, the project had grown to seven volumes, it has expanded since. His initial collaborator was the historian Wang Ling, whom he had met in Lizhuang and obtained a position for at Trinity; the first years were devoted to compiling a list of every mechanical invention and abstract idea, made and conceived in China. These included cast iron, the ploughshare, the stirrup, printing, the magnetic compass and clockwork escapements, most of which were thought at the time to be western inventions; the first volume appeared in 1954. The publication received widespread acclaim, which increased to the lyrical as further volumes appeared, he wrote fifteen volumes himself, the regular production of further volumes continued after his death in 1995. Volume III was divided, so that 27 volumes have now been published. Successive volumes are published as they are completed, which means that they do not appear in the order contemplated in the project's prospectus. Needham's final organising schema was: Vol. I.
Introductory Orientations Vol. II. History of Scientific Thought Vol. III. Mathematics and the Sciences of the Heavens and Earth Vol. IV. Physics and Physical Technology Vol. V. Chemistry and Chemical Technology Vol. VI. Biology and Biological Technology Vol. VII; the Social Backgr
A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry. A triangle with vertices A, B, C is denoted △ A B C. In Euclidean geometry any three points, when non-collinear, determine a unique triangle and a unique plane. In other words, there is only one plane that contains that triangle, every triangle is contained in some plane. If the entire geometry is only the Euclidean plane, there is only one plane and all triangles are contained in it; this article is about triangles in Euclidean geometry, in particular, the Euclidean plane, except where otherwise noted. Triangles can be classified according to the lengths of their sides: An equilateral triangle has all sides the same length. An equilateral triangle is a regular polygon with all angles measuring 60°. An isosceles triangle has two sides of equal length. An isosceles triangle has two angles of the same measure, namely the angles opposite to the two sides of the same length; some mathematicians define an isosceles triangle to have two equal sides, whereas others define an isosceles triangle as one with at least two equal sides.
The latter definition would make all equilateral triangles isosceles triangles. The 45–45–90 right triangle, which appears in the tetrakis square tiling, is isosceles. A scalene triangle has all its sides of different lengths. Equivalently, it has all angles of different measure. Hatch marks called tick marks, are used in diagrams of triangles and other geometric figures to identify sides of equal lengths. A side can be marked with a pattern of short line segments in the form of tally marks. In a triangle, the pattern is no more than 3 ticks. An equilateral triangle has the same pattern on all 3 sides, an isosceles triangle has the same pattern on just 2 sides, a scalene triangle has different patterns on all sides since no sides are equal. Patterns of 1, 2, or 3 concentric arcs inside the angles are used to indicate equal angles. An equilateral triangle has the same pattern on all 3 angles, an isosceles triangle has the same pattern on just 2 angles, a scalene triangle has different patterns on all angles since no angles are equal.
Triangles can be classified according to their internal angles, measured here in degrees. A right triangle has one of its interior angles measuring 90°; the side opposite to the right angle is the longest side of the triangle. The other two sides are called the catheti of the triangle. Right triangles obey the Pythagorean theorem: the sum of the squares of the lengths of the two legs is equal to the square of the length of the hypotenuse: a2 + b2 = c2, where a and b are the lengths of the legs and c is the length of the hypotenuse. Special right triangles are right triangles with additional properties that make calculations involving them easier. One of the two most famous is the 3–4–5 right triangle, where 32 + 42 = 52. In this situation, 3, 4, 5 are a Pythagorean triple; the other one is an isosceles triangle. Triangles that do not have an angle measuring 90° are called oblique triangles. A triangle with all interior angles measuring less than 90° is an acute triangle or acute-angled triangle.
If c is the length of the longest side a2 + b2 > c2, where a and b are the lengths of the other sides. A triangle with one interior angle measuring more than 90° is an obtuse triangle or obtuse-angled triangle. If c is the length of the longest side a2 + b2 < c2, where a and b are the lengths of the other sides. A triangle with an interior angle of 180° is degenerate. A right degenerate triangle has collinear vertices. A triangle that has two angles with the same measure has two sides with the same length, therefore it is an isosceles triangle, it follows that in a triangle where all angles have the same measure, all three sides have the same length, such a triangle is therefore equilateral. Triangles are assumed to be two-dimensional plane figures. In rigorous treatments, a triangle is therefore called a 2-simplex. Elementary facts about triangles were presented by Euclid in books 1–4 of his Elements, around 300 BC; the sum of the measures of the interior angles of a triangle in Euclidean space is always 180 degrees.
This fact is equivalent to Euclid's parallel postulate. This allows determination of the measure of the third angle of any triangle given the measure of two angles. An exterior angle of a triangle is an angle, a linear pair to an interior angle; the measure of an exterior angle of a triangle is equal to the sum of the measures of the two interior angles that are not adjacent to it. The sum of the measures of the three exterior angles of any triangle is 360 degrees. Two triangles are said to be similar if every angle of one triangle has the same measure as the corresponding angle in the other triangle; the corresponding sides of similar triangles have lengths that are in the same proportion, this property is sufficient to establish similarity. Some basic theorems about similar triangles are: If and only if one pair of internal angles of two triangles have the sam
Multilateration is a navigation and surveillance technique based on the measurement of the times of arrival of energy waves having a known propagation speed. The time origin for the TOAs is arbitrary. For surveillance, a subject of interest – in cooperative surveillance a vehicle – transmits to multiple receiving stations having synchronized'clocks'. For navigation, multiple synchronized stations transmit to a user receiver. To find the coordinates of a user in n dimensions, at least n + 1 TOAs must be measured. Multilateration systems are called hyperbolic systems, for reasons discussed below. One can view a multilateration system as measuring n + 1 TOAs, either: determining the time of transmission and n user coordinates. Systems and algorithms have been developed for both concepts; the latter is addressed first. A TDOA, when multiplied by the propagation speed, is the difference in the true ranges between the user and the two stations involved; the former is addressed second. In practice, TOT/non-TDOA systems determine a user/vehicle location in three dimensions.
A TOA, when multiplied by the propagation speed, is termed a pseudo range. However, there is no conceptual reason that TDOA or TOT algorithms should be linked to a number of dimensions. For surveillance, a TDOA system determines the difference in the subject of interest's distance to pairs of stations at known fixed locations. For one station pair, the distance difference results in an infinite number of possible subject locations that satisfy the TDOA; when these possible locations are plotted, they form a hyperbolic curve. To locate the exact subject's position along that curve, multilateration relies on multiple TDOAs. For two dimensions, a second TDOA, involving a different pair of stations, will produce a second curve, which intersects with the first; when the two curves are compared, a small number of possible user locations are revealed. Multilateration surveillance can be performed without the cooperation or knowledge of the subject being surveilled. TDOA multilateration was a common technique in earth-fixed radio navigation systems, where it was known as hyperbolic navigation.
These systems are undemanding of the user receiver, as its'clock' can have low-performance/cost and is unsynchronized with station time. The difference in received signal timing can be measured visibly using an oscilloscope; this formed the basis of a number of used navigation systems starting in World War II with the British Gee system and several similar systems deployed over the next few decades. The introduction of the microprocessor simplified operation, increasing popularity during the 1980s; the most popular TDOA hyperbolic navigation system was Loran-C, used around the world until the system was shut down in 2010. The widespread use of satellite navigation systems like the Global Positioning System have made TDOA systems redundant, most have been decommissioned. GPS is a hyperbolic navigation system, but determines the TOT in order to provide accurate time. Multilateration should not be confused with any of: true range multilateration, which uses distance measurements from two or more sites triangulation, which uses the measurement of angles direction finding which does not compute a distance.
All of these systems are used with radio navigation and surveillance systems. Prior to deployment of GPS and other global navigation satellite systems, multilateration systems were defined as TDOA systems – i.e. systems that form TDOAs as the first step in processing a set of measured TOAs. As result of deployment of GNSSs, two issues arose: What system type are they? What are the defining characteristic of a multilateration system? The technical answer to has long been known: GPS and other GNSSs are multilateration navigation systems with moving transmitters. However, because the transmitters are synchronized not only each other but a time standard, GNSS receivers are sources of time, provided they compute TOT; this requires different solution algorithms than older TDOA algorithms. Thus, a case can be made that GNSSs are a separate category of systems – e.g. hyperbolic navigation and timing systems or hyperbolic navigation with moving transmitters. There is no authoritative answer to. However, a reasonable two-part answer is a system whose use only involves measurement of TOAs or only pseudo ranges.
This definition includes GNSSs as well as TDOA systems. Multilateration is used in civil and military applications to either locate a vehicle by measuring the TOAs of a signal from the vehicle at multiple stations having known coordinates and accurate, synchronized'clocks' or enable the vehicle to locate itself relative to multiple transmitters at known locations and having synchronized clocks using their signal TOAs; when the stations are fixed to the eart
A weapon, arm or armament is any device that can be used with intent to inflict damage or harm. Weapons are used to increase the efficacy and efficiency of activities such as hunting, law enforcement, self-defense, warfare. In broader context, weapons may be construed to include anything used to gain a tactical, material or mental advantage over an adversary or enemy target. While ordinary objects such as sticks, cars, or pencils can be used as weapons, many are expressly designed for the purpose – ranging from simple implements such as clubs and axes, to complicated modern intercontinental ballistic missiles, biological weapons and cyberweapons. Something, re-purposed, converted, or enhanced to become a weapon of war is termed weaponized, such as a weaponized virus or weaponized laser; the use of objects as weapons has been observed among chimpanzees, leading to speculation that early hominids used weapons as early as five million years ago. However, this can not be confirmed using physical evidence because wooden clubs and unshaped stones would have left an ambiguous record.
The earliest unambiguous weapons to be found are the Schöningen spears, eight wooden throwing spears dating back more than 300,000 years. At the site of Nataruk in Turkana, numerous human skeletons dating to 10,000 years ago may present evidence of traumatic injuries to the head, ribs and hands, including obsidian projectiles embedded in the bones that might have been caused from arrows and clubs during conflict between two hunter-gatherer groups, but the evidence interpretation of warfare at Nataruk has been challenged. The earliest ancient weapons were evolutionary improvements of late neolithic implements, but significant improvements in materials and crafting techniques led to a series of revolutions in military technology; the development of metal tools began with copper during the Copper Age and was followed by the Bronze Age, leading to the creation of the Bronze Age sword and similar weapons. During the Bronze Age, the first defensive structures and fortifications appeared as well, indicating an increased need for security.
Weapons designed to breach fortifications followed soon after, such as the battering ram, in use by 2500 BC. The development of iron-working around 1300 BC in Greece had an important impact on the development of ancient weapons, it was not the introduction of early Iron Age swords, however, as they were not superior to their bronze predecessors, but rather the domestication of the horse and widespread use of spoked wheels by c. 2000 BC. This led to the creation of the light, horse-drawn chariot, whose improved mobility proved important during this era. Spoke-wheeled chariot usage peaked around 1300 BC and declined, ceasing to be militarily relevant by the 4th century BC. Cavalry developed; the horse increased the speed of attacks. In addition to land based weaponry, such as the trireme, were in use by the 7th century BC. European warfare during the Post-classical history was dominated by elite groups of knights supported by massed infantry, they were involved in mobile combat and sieges which involved various siege tactics.
Knights on horseback developed tactics for charging with lances providing an impact on the enemy formations and drawing more practical weapons once they entered into the melee. By contrast, infantry, in the age before structured formations, relied on cheap, sturdy weapons such as spears and billhooks in close combat and bows from a distance; as armies became more professional, their equipment was standardized and infantry transitioned to pikes. Pikes are seven to eight feet in length, used in conjunction with smaller side-arms. In Eastern and Middle Eastern warfare, similar tactics were developed independent of European influences; the introduction of gunpowder from the Asia at the end of this period revolutionized warfare. Formations of musketeers, protected by pikemen came to dominate open battles, the cannon replaced the trebuchet as the dominant siege weapon; the European Renaissance marked the beginning of the implementation of firearms in western warfare. Guns and rockets were introduced to the battlefield.
Firearms are qualitatively different from earlier weapons because they release energy from combustible propellants such as gunpowder, rather than from a counter-weight or spring. This energy is released rapidly and can be replicated without much effort by the user; therefore early firearms such as the arquebus were much more powerful than human-powered weapons. Firearms became important and effective during the 16th century to 19th century, with progressive improvements in ignition mechanisms followed by revolutionary changes in ammunition handling and propellant. During the U. S. Civil War new applications of firearms including the machine gun and ironclad warship emerged that would still be recognizable and useful military weapons today in limited conflicts. In the 19th century warship propulsion changed from sail power to fossil fuel-powered steam engines. Since the mid-18th century North American French-Indian war through the beginning of the 20th century, human-powered weapons were reduced from the primary weaponry of the battlefield yielding to gunpowder-based weaponry.
Sometimes referred to as the "Age of Rifles", this period was characterized by the development of firearms for infantry and cannons for support, as well as the beginnings of mechanized weapons such as the machine gun. Of particular note, Howitzers were able to destroy masonry fortresses and other fortifications, this single invention caused a Revolution in