Added 1 February 2004
A BRIEF WORD ABOUT CROSSBOWS The crossbow played an important role in the late Medieval period. The crossbow was really the first hand-held weapon that could be used by an untrained soldier to injure or kill a knight in plate armour. The most powerful crossbows could penetrate armour and kill at 200 yards. Crossbows are easier to aim than longbows because the crossbowman doesn't have to use a hand to hold the string back while aiming. (For more information on crossbows versus longbows, go HERE.) On a similar note, a crossbow can be loaded long before the bowman might need to shoot. In this way, the bowman would be able to shoot immediately if surprised. Crossbows require less upper body strength to operate as well. One can use both arms to span (draw back) a crossbow. Crossbows do, of course, come with a price. That price is in efficiency and in the firing rate. Efficiency is a more technical problem.
No bow is perfectly efficient, but Medieval crossbows were particularly inefficient. The reason for this is that the draw length and the lathe (also called a prod) of crossbows are short. So even though a crossbow may have a great deal of stored energy when spanned, the tips of the lathe do not have enough time to reach the maximum velocity, so the amount of stored energy is not transferred fully to the bolt. It is the lathe tip velocity that determines the speed of the bolt that is loosed. (For a more detailed comparison on crossbow power versus longbow power, go HERE.)
This problem could have been alleviated with a longer draw length or a longer lath, but that would increase the weight and bulkiness of the crossbow, which are already two distinct disadvantages of the Medieval crossbow.
CROSSBOW USES (War, Sport and the Sinister)
Crossbows were mainly either weapons of war or sport (hunting and target shooting). Of these, most were probably weapons of war. The larger war crossbows were used to defend fortifications. Smaller crossbows (~4 ft.) could be quite effective in open battle when used correctly though. Since a crossbowman is particularly vulnerable while reloading the crossbow, he requires some sort of defense (a wall or a shield) to be effective in battle.
Though popular sporting items, crossbows were very expensive, and only the wealthy could afford them. Crossbows were often highly prized by assasins. There are a number of laws that address this problem in particular. Assasins would be the main users of the smallest crossbows, as they are more easily hidden and transported.
WORKING MEDIEVAL CROSSBOWS (what they tell us)
There are working examples of Medieval crossbows, and from them we can get a good feel for the range and power they had. Throughout the Medieval Period though, crossbows became more powerful. Sir Ralph Payne-Gallwey loosed a bolt from an actual Medieval crossbow spanned with a cranequin and achieve a cast of 490 yards. The ordinary 15th. century crossbow would likely cast a bolt 370-380 yards. These crossbows would surely outperform almost any longbow in terms of distance, but the accuracy of the crossbow at those ranges would likely be poor at best. At point blank range, the crossbow almost certainly had very high penetrating power.
The crossbow was probably introduced into Europe circa 900 CE, and possibly a couple of hundred years earlier. From this time until the 12th. century, the prods of crossbows were self-bows, or made out of one piece of wood. Composite prods, made out of horn and/or sinew(tendon) and/or wood were introduced to Europe in the 12th. century. The composite bow was the technology of the Saracens, and was a marked improvement over the wood bow. Steel prods were made and used after 1350 CE. The tiller of each type crossbow was usually wood, though was sometimes also composite. Self and composite crossbows usually employed a bridle made of rope or sinew to attach the prod to the tiller. With this type of method, the prod is essentially just tied onto the tiller. This method was occasionally used for steel prods, though they were more often held within the tiller itself, rather than lashed to the end of it.
The nut of almost all types of crossbows was often made of horn.