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The English Longbow
One of the most powerful weapons of the Medieval period was the English Longbow. This bow differed from many other bows in several ways: the amount of time a yeoman would spend practicing with his bow, the physical characteristics of the bow itself, and the size and weight of the projectile it was capable of shooting.
Longbows are among the long family of bows. They tend to be at least four and a half feet long, and would more typically be around the height of the man shooting the bow. They were made of yew tree limbs in a fairly typical fashion with the bow being made from half heartwood and half sapwood. The heartwood layer faces the string, and the sapwood faces the target. This is because the properties of each type of wood lend themselves to their task in this arrangement. Sapwood is young wood that can readily resist stretching, whereas heartwood has aged and become more structured, so it resists compression. Like a tree can bend in the wind and remain undamaged, so a bow bends in the hands of an archer and survives the use.
Because of the art of making such a bow combined with its stature, the longbow had a high draw weight and a relatively long release time. Combined, these factors meant that this particular kind of bow would release an arrow from full draw that:
1) weighed more than an average arrow
2) had a higher than average initial velocity
Because of these factors, arrows fired from a longbow had a much higher energy on impact. They were effective against armors that were sufficient against lesser bows.
Considering the famous Battle of Agincourt, in which reportedly an army of English, outnumbered ten to one by the French, engaged them and killed an estimated 10,000 men while the French managed only to kill roughly a hundred English; it is likely that the English use of the longbow helped secure the English empire a predominant place as a world power until modern times.