Crossbow

A crossbow is a ranged weapon using an elastic launching device consisting of a bow-like assembly called a prod, mounted horizontally on a main frame called a tiller, which is hand-held in a similar fashion to the stock of a long gun. Crossbows shoot arrow-like projectiles called bolts or quarrels. A person who shoots crossbow is called a crossbowman, an arbalister or an arbalist (after the arbalest, a European crossbow variant used during the 12th century).^[1]

Crossbows and bows use the same elastic launch principles, but differ in that an archer using a bow must draw-and-shoot in a quick and smooth motion with limited or no time for aiming, while a crossbow's design allows it to be spanned and cocked ready for use at a later time and thus affording them unlimited time to aim. When shooting bows, the archer must fully perform the draw, holding the string and arrow using various techniques while pulling it back with arm and back muscles, and then either immediately shooting instinctively without a period of aiming, or holding that form while aiming. Both demand some physical strength to do so using bows suitable for warfare, though this is easier using lighter draw-weight hunting bows. As such, their accurate and sustained use in warfare takes a lot of practice.

Crossbows avoid these potential problems by having trigger-released cocking mechanisms to maintain the tension on the string once it has been spanned – drawn – into its ready-to-shoot position, allowing these weapons to be carried cocked and ready and affording their users time to aim them. This also allows them to be readied by someone assisting their users, so multiple crossbows can be used one after the other while others reload and ready them. Crossbows are spanned into their cocked positions using a number of techniques and devices, some of which are mechanical and employ gear and pulley arrangements – levers, belt hooks, pulleys, windlasses and cranequins – to overcome very high draw weight.^[2] These potentially achieve better precision and enable their effective use by less familiarised and trained personnel, whereas the simple and composite warbows of, for example, the English and the steppe nomads require years of training, practice and familiarisation.

These advantages for the crossbow are somewhat offset by the longer time needed to reload a crossbow for further shots, with the crossbows with high draw weights requiring sophisticated systems of gears and pulleys to overcome their huge draw weights that are very slow and rather awkward to employ on the battlefield. Medieval crossbows were also very inefficient, with short shot stroke lengths from the string lock to the release point of their bolts, along with the slower speeds of their steel prods and heavy strings, despite their massive draw weights compared to bows, though modern materials and crossbow designs overcome these shortcomings.

The earliest known crossbows were made in the first millennium BC, as early as the 7th century BC in ancient China and as early as the 1st century AD in Greece (as the gastraphetes).^[3][4] Crossbows brought about a major shift in the role of projectile weaponry in wars, such as during Qin's unification wars and later Han campaigns against northern nomads and western states. The medieval European crossbow was called by many names, including "crossbow" itself; most of these names derived from the word ballista, an ancient Greek torsion siege engine similar in appearance but different in design principle.^[5]

In modern times, firearms have largely supplanted bows and crossbows as weapons of war, but crossbows remain widely used for competitive shooting sports and hunting, and for relatively silent shooting.^[6]