A crossbow is a weapon consisting of a bow mounted on a stock that shoots projectiles, often called bolts. A mechanism in the stock holds the bow in its fully-drawn position until it is shot by releasing a trigger. Crossbows played a significant role in the warfare of North Africa, Europe and Asia. Crossbows are used today primarily for target shooting and hunting.

A crossbow is basically a bow mounted on a stick (called a tiller or stock) with a mechanism in it which holds the drawn bowstring. The earliest designs utilized a slot in the stock, down into which the cocked string was placed. This is sometimes called a 'notchlock' crossbow[citation needed]. To fire this design, a vertical rod is thrust up through a hole in the bottom of the notch, forcing the string out. This rod is usually attached perpendicular to a rear-facing firing lever called a trigger or 'tickler'. A later design, predominant through the end of the 16th century, utilized a rolling cylindrical pawl called a 'nut' to retain the cocked string. This nut has a perpendicular center slot for the bolt, and an intersecting axial slot for the string, along with a lower face or slot against which the internal trigger sits. They often also have some form of strengthening internal 'sear' or trigger face, usually of metal. These 'roller nuts' were either free-floating in their close-fitting hole across the stock, tied in with a binding of sinew or other strong cording, or mounted on a metal axle or pins. Removeable or integral plates of wood, ivory or metal on the sides of the stock kept the nut in place laterally. Nuts were made of antler, bone, ivory or metal (usually brass). A trigger system, (usually made of iron or steel from medieval times onwards), was used to retain the force of the cocked string in the nut and then release the nut to spin and the string to shoot the bolt. Sophisticated bronze triggers with safety notches are known to have been used on crossbows from ancient China. Complicated iron triggers that could be released with little strength are known in Europe from the early 1400s. As a result crossbows could be kept cocked and ready to shoot for some time with little effort, allowing crossbowmen to aim better.

The bow (called the "prod" or "lath" on a crossbow) of early crossbows were made of a single piece of wood, usually ash or yew. Composite bows are made from layers of different material—often wood, horn and sinew—glued together and bound with animal tendon. These composite bows, made of several layers, are much stronger and more efficient in releasing energy than simple wooden bows. As steel became more widely available in Europe around the 14th century, steel prods came into use.

The crossbow prod is very short compared to ordinary bows, resulting in a short draw length. The resulting thick prods are less efficient at releasing energy, but more energy can be stored by a crossbow. Traditionally the prod was often lashed to the stock with rope, whipcord, or other strong cording. This cording is called the bridle.

The strings for a crossbow are typically made of strong fibers that would not tend to fray. Whipcord was very common; however linen, hemp, and sinew were used as well. In wet conditions, twisted mulberry root was occasionally used.

The problem when handling crossbows was the comparably short draw length and the great amount of energy needed. Some light crossbows could be drawn by hand, but for others the help of mechanical devices was needed. Some crossbows had prods of up to at least 800 pounds of draw, if not more. Draw-weights of 500 pounds were common. The simplest version of mechanical cocking device was a hook attached to a belt, drawing the bow by straightening the legs. Other devices were hinged levers which either pulled or pushed the string into place, cranked rack-and-pinion devices called 'cranequins' and multiple cord-and-pulley cranked devices called windlasses.

Crossbows exist in different variants, one way to classify them is the acceleration system, another the size and energy, degree of automation or projectiles.

The simplest acceleration system is a straight or bent prod and it is probably the earliest version of a crossbow.

A recurve crossbow is a bow that has tips curving away from the archer. The recurve bow's bent limbs have a longer draw length than an equivalent straight-limbed bow, giving a more acceleration to the projectile and less hand shock. Recurved limbs also put greater strain on the materials used to make the bow, and they may make more noise with the shot.

Multiple bow systems (for example a Chuangzi Nu) have a special system of pulling the sinew via several bows(which can be recurve bows). The workings can be compared to a modern compound bow system. The weapon uses several different bows instead of one bow with a tackle system to achieve a higher acceleration of the sinew via the multiplication with each bow's pulling effect.

A compound crossbow is a modern crossbow and similar to a compound bow, The limbs are usually much stiffer than those of a recurve crossbow. This limb stiffness makes the compound bow more energy efficient than other bows, but the limbs are too stiff to be drawn comfortably with a string attached directly to them. The compound bow has the string attached to the pulleys, one or both of which has one or more cables attached to the opposite limb. When the string is drawn back, the string causes the pulleys to turn. This causes the pulleys to pull the cables, which in turn causes the limbs to bend and thus store energy. The use of this levering system gives the compound bow a characteristic draw-force curve which rises to a peak weight and then "lets off" to a lower holding weight.

In size the smallest are pistol crossbows. Others are simple long stocks with the crossbow mounted on them. These could be shot from under the arm. The next step in development was rifle shaped stocks that allowed better aiming. The arbalest was a heavy crossbow which required special systems for pulling the sinew via windlasses. For siege warfare the size of crossbows was further increased to hurl large projectiles such as rocks at fortifications. The required crossbows needed a massive base frame and powerful windlass devices. Such devices include the oxybeles. The ballista has torsion springs replacing the elastic prod of the oxybeles, but later also developed into smaller versions. "Ballista" is still the root word for crossbow in Romance languages such as Italian (balestra).

The repeating crossbow automated the separate actions of stringing the bow, placing the projectile and shooting. This way the task can be accomplished with a simple one-handed movement, while keeping the weapon stationary. As a result, it is possible to shoot at a faster rate compared to unmodified version. The Chinese repeating crossbow, Chu Ko Nu, is a small handheld crossbow that accomplishes the task with a magazine containing a number of bolts on top and the mechanism is worked by moving a rectangular lever forward and backward.

Bowguns are a type of handheld crossbow which rather than arrows or bolts shoots spherical projectiles from stone, clay or lead. The simplest version has a loop for the projectile in the sinew or more sophisticated version have a barrel.

The arrow-like projectiles of a crossbow are called bolts. These are much shorter than arrows, but can be several times heavier. There is an optimum weight for bolts to achieve maximum kinetic energy, which varies depending on the strength and characteristics of the crossbow. In ancient times the bolts of a strong crossbow were usually several times heavier than arrows. Modern bolts are stamped with a proof mark to ensure their consistent weight. Bolts typically have three fletches, commonly seen on arrows. Crossbow bolts can be fitted with a variety of heads, some with sickle-shaped heads to cut rope or rigging; but the most common today is a four-sided point called a quarrel. A highly specialized type of bolt can be employed to collect blubber biopsy samples used in biology research.

Crossbows could be adapted to also shoot stones or lead bullets. Primarily used for hunting wildfowl, these usually have a double string with a pouch between the strings to hold the projectile.

The ancient crossbow often included a metal grid serving as iron sights. Modern crossbow sights often use similar technology to modern firearm sights such red dot sights and telescopic sights. Many crossbow scopes feature multiple crosshairs to compensate for the significant effects of gravity over different ranges.

Quivers can be mounted to hold ammunition. These are often made from plastic and usually hold the bolts in fixed positions along the structure. A popular detachable design consists of a main arm that is attached to the weapon, a plate on one end that secures four or more individual bolts at a point on their shafts and at the other end a cover that secures their heads. This kind of quiver is attached under the front of the crossbow, parallel to the string and is designed to be quickly detached and reattached. Other designs hold bolts underneath the crossbow parallel to the stock, sometimes on either side of the crossbow.

A major cause of the sound of firing a crossbow is vibration of various components. Crossbow silencers are multiple components placed on high vibration parts such as the string and limbs to dampen vibration and suppress the sound of loosing.

The earliest documentation of a Chinese crossbow is in scripts from the 4th–3rd century BC attributed to the followers of Mozi. This source refers the use of a giant crossbow catapult to the 6th to 5th century BC, corresponding to the late Spring and Autumn Period. Sun Tzu's influential book The Art of War (first appearance dated in between 500 BC to 300 BC) refers in chapter V to the traits and in XII to the use of crossbows. One of the earliest reliable records of this weapon in warfare is from an ambush, the Battle of Ma-Ling in 341 BC. By the 200s BC, the crossbow was well developed and quite widely used in China. Several remains of them have been found among the soldiers of the Terracotta Army in the tomb of Emperor Qin Shi Huang (260-210 BC).

The earliest date for the crossbow is from the 5th century BC, from the Greek world. This was called the gastraphetes, which could store more energy than the Greek bows, and was used in the Siege of Motya in 397 BC. This was a key Carthaginian stronghold in Sicily, as described in the 1st century AD by Hero of Alexandria in his book Belopoeica. This date for the introduction of the crossbow in the Mediterranean is not accepted without doubt because of the temporal difference between writer and event and the lack of other sources stating the same. At least Alexander's siege of Tyre in 332 BC provides reliable sources for the use of these weapons by the Greek besiegers.

The efficiency of the gastraphetes was improved by introducing the ballista. Its application in sieges and against rigid infantry formations featured more and more powerful projectiles, leading to technical improvements and larger ballistae. The smaller sniper version was often called Scorpio. An example for the importance of ballistae in Hellenistic warfare is the Helepolis, a siege tower employed by Demetrius during the Siege of Rhodes in 305 BC. At each level of the moveable tower were several ballistae. The large ballistae at the bottom level were designed to destroy the parapet and clear it of any hostile troop concentrations while the small armorbreaking scorpios at the top level sniped at the besieged. This suppressive shooting would allow them to mount the wall with ladders more safely.

The use of crossbows in European warfare dates back to Roman times and is again evident from the battle of Hastings until about 1500 AD. They almost completely superseded hand bows in many European armies in the twelfth century for a number of reasons. Although a longbow had greater range, could achieve comparable accuracy and faster shooting rate than an average crossbow, crossbows could release more kinetic energy and be used effectively after a week of training, while a comparable single-shot skill with a longbow could take years of practice.

In the armies of Europe, mounted and unmounted crossbowmen, often mixed with javeliners and archers, occupied a central position in battle formations. Usually they engaged the enemy in offensive skirmishes before an assault of mounted knights. Crossbowmen were also valuable in counterattacks to protect their infantry. The rank of commanding officer of the crossbowmen corps was one of the highest positions in any army of this time. Along with polearm weapons made from farming equipment, the crossbow was also a weapon of choice for insurgent peasants such as the Taborites.

Mounted knights armed with lances proved ineffective against formations of pikemen combined with crossbowmen whose weapons could penetrate most knights' armor. The invention of pushlever and ratchet drawing mechanisms enabled the use of crossbows on horseback, leading to the development of new cavalry tactics. Knights and mercenaries deployed in triangular formations, with the most heavily armored knights at the front. Some of these riders would carry small, powerful all-metal crossbows of their own. Crossbows were eventually replaced in warfare by gunpowder weapons, although early guns had slower rates of fire and much worse accuracy than contemporary crossbows. Later, similar competing tactics would feature harquebusiers or musketeers in formation with pikemen, pitted against cavalry firing pistols or carbines.

In Asia, crossbows were used as antipersonnel and siege weapons. The Chinese developed the repeating crossbow with an automatic reloading system.

The Saracens called the crossbow qaws Ferengi, or "Frankish bow", as the Crusaders used the crossbow against the Arab and Turkoman horsemen with remarkable success. The adapted crossbow was used by the Islamic armies in defence of their castles. Later footstrapped version become very popular among the Muslim armies in Spain. During the Crusades, Europeans were exposed to Saracen composite bows, made from layers of different material—often wood, horn and sinew—glued together and bound with animal tendon. These composite bows could be much more powerful than wooden bows, and were adopted for crossbow prods across Europe.

In Western Africa and Central Africa, crossbows serve as a scout weapon and for hunting, with enslaved Africans bringing the technology to America. In the American south, the crossbow was used for hunting when firearms or gunpowder were unavailable because of economic hardships or isolation. Light hunting crossbows were traditionally used by the Inuit in Northern America.

Crossbows are mostly used for target shooting in modern archery.

In many parts of the world they are still used for hunting, such as parts of North America, parts of Asia, Australia and Africa. Other uses with special projectiles are in whale research to take blubber biopsy samples without harming the whales. A few modern military units are equipped with crossbows as even lower noise alternatives to suppressed firearms.

With a crossbow, archers could release a draw force far in excess of what they could have handled with a bow. Moreover, crossbows could be kept cocked and ready to shoot for some time with little effort, allowing crossbowmen to aim better. The disadvantage is the greater weight and clumsiness compared to a bow, as well as the slower rate of fire and the lower efficiency of the acceleration system.

The Second Lateran Council under Pope Innocent II in 1139 may have banned the use of crossbows against Christians. The authenticity, interpretation and translation of this source is contested.

Today the crossbow often has a complicated legal status due to the possibility of lethal use and its similarities with both firearms and archery weapons.Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts.
Virtual Magic is a human knowledge database blog. Text Based On Information From Wikipedia, Under The GNU Free Documentation License. Copyright (c) 2007 Virtual Magic. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".

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