The Crossbow vs. the Longbow
Author: Melvar al'Caarn
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 can penetrate armour and kill at 200 yards. Longbowmen could certainly penetrate plate mail though perhaps not at such a great distance, but longbowman are generally highly trained soldiers. This meant that they are also expensive, and that they could not be replaced easily.
Anyone could use a crossbow though. Crossbows are easier to aim than longbows because the crossbowman doesn't have to use a hand to hold the string back while aiming. 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 draw back a crossbow. Crossbows do, of course, come with a price. That price is in efficiency and in the firing rate. Longbowman could shoot 2-5 times more frequently in a given time than a crossbowman.
Although it is impossible for any bow to be perfectly efficient, crossbows are particularly inefficient when compared to longbows. The reason for this is that the draw length and the "bow" of crossbows are much shorter than those of longbows. So even though a crossbow may have more stored energy when spanned, the tips of the bow do not have enough time to reach the maximum velocity that the amount of stored energy would otherwise allow. It is the bow tips velocity that determines the speed of the bolt that is loosed.
This problem could have been eliminated with a longer draw length or a longer bow, but that would increase the weight and bulkiness of the crossbow, which are already two distinct disadvantages of crossbows. A heavier arrow loosed by the longbow would have had a significantly reduced exit velocity. While a heavier arrow from a crossbow would have much the same speed and power and would make a bigger "punch" on impact.
The usage of the crossbow
The main usage of the crossbow is for defence, for example on the city wall. But smaller crossbows can be used on the field of battle as well. But not in the main battle, they are just too vulnerable. Crossbows are also used outside of the battlefield and inside the halls, by assassins. They love the relay small crossbows since they have the same killing force as a bow but are much smaller and easier to conceal.
What is the best weapon of choice in battle?
Well, that depends on where the battle is and what resistance you are facing. The longbow is best in field battles while the crossbow is best in close quarters such as cities. The longbow are good for cower fire to infantry troops or cavalry while they are attacking. It can also be used as a defensive weapon, as Perrin does in The Shadow Rising, Chapter 56. "All along the ranks, bows rose together... The snap of bow strings were lost in the roar from the trollocs, but goose-fletched hail streaked the sky as it arched out, plunged down into the black-mailed horde"
The crossbow is as said earlier a faster shooter on the first shot but has a really long reload time. During the reload the shooter are quite vulnerable. So normally there is a "team" around one crossbow, one person handling the bow and one whit a large shield maybe a short sword defending the crossbow during reload. That way the crossbow team is very efficient in battle (The Legion of the Dragon, the force used by Rand in A Crown of Swords to take Illian).
A Crown of Swords, Chapter 41: "In another direction he spotted some of the legion of the dragon... An officer marked by a tall red plume on his helmet strode in front of some twenty men carrying wide shields as tall as their shoulders, followed by perhaps two hundred more with heavy crossbows. How would they fight?"
So what weapon is best?
To be honest they are too alike and too different to say that either one is the best. But the fact that everyone can hit a target with a crossbow gives it an edge.