by Barry Parker
The hail of crossbow darts fell short, but the barrage of English arrows that followed didn't, and it was effective. The barrage continued, and, as a result, the crossbow men couldn't get close enough for their bows to be effective. Seeing their situation, many of the crossbow men began retreating through the lines of French knights behind them. Angered by the retreat, the knights began hacking at their own men, killing many of them. Then they decided it was time to charge. They forced their horses forward over the retreating crossbow men, trampling many of them. The English bowmen continued firing at the knights, and to the surprise of the French, many of the arrows penetrated their armor. As a result, many of them began to fall, and as more and more fell, they began blocking the men behind, and bodies began falling upon bodies.
When the battle was over the French had suffered tremendous casualties. According to one estimate, four thousand French knights were killed and as many as two thousand French archers. The English, on the other hand, suffered few casualties—most estimates were under three hundred. The decisive factor was the new longbow, and it would continue to play an important role for another hundred years or more.
The longbow was also decisive in the Battle of Agincourt in October 1415. By this time it had become even more effective. Again the English and the French were involved; this time the English army of about six thousand men was led by Henry V, and the French army numbered twenty-five thousand or more. The battle was fought on a narrow strip of open land near Agincourt.6
With a four or five to one advantage, the French were likely overconfident. They had eight thousand heavily armed men, but they would only be effective in hand-to-hand battle, so they had to get close. Furthermore, between the two armies was a recently plowed field, and it had rained heavily during the previous days. So it was muddy, much to the detriment of the French, many of whom were heavily armored. But on the English side, many of the troops were sick and exhausted from days of marching.
The English archers drove long, sharp stakes into the ground at an angle pointed toward the French line. This helped protect them from cavalry charges by the French knights. The French formed up in three lines, with the men-at-arms in the front and the archers and the crossbowman behind. The French were expecting the English to launch a frontal attack, but they didn't. Instead, the English longbow men opened up with a barrage of arrows. The well-trained longbow men could now fire up to fifteen arrows a minute, so within seconds there were thousands of arrows in the air. Furthermore, to the surprise of the French, the arrows easily penetrated their armor. Many of the arrows struck the horses on their backs and flanks, causing them to panic; as a result, wounded and panicked horses galloped through the advancing infantry, trampling them.7
The French men-at-arms tried to protect themselves as they moved forward. Because their helmets were the weakest part of their armor, most of them lowered their heads to avoid getting shot in the eye or through the breathing holes in the helmet. This restricted their vision. Along with this, they had to walk through knee-deep mud in places, and also over and around fallen comrades. And the barrage of arrows seemed to be unending. Soon the French ground troops were exhausted and disheartened; furthermore, they couldn't get close enough for hand-to-hand fighting.
To make things worse, the second and third line of French warriors didn't know what was happening up front, and they continued to forge forward, and soon they suffered the same fate. The battle lasted three hours, and in the end four thousand to ten thousand French were dead (according to various estimates), with English casualties as low as a few hundred. Many of the elite, including dukes, constables, royals, and so on, were killed. And again, it was the English longbow that was the decisive factor.
ORIGIN AND PHYSICS OF THE LONGBOW
The longbow was developed in several countries independently. In Great Britain it was first developed by the Welsh. And there's no doubt that they made significant advances in its construction, not from understanding any of the science behind it, but mostly from trial and error.8
The English felt the effects of the Welsh longbow early on. It was used against them, mostly in ambushes and skirmishes at first, but eventually in larger battles, such as one in 1402 where the Welsh used it quite effectively against the English. This, of course, caused considerable concern for the English, and it also piqued their curiosity. They soon incorporated Welsh archers into their own army and learned their techniques.
The first English longbows were made of a single piece of wood—usually yew because it was particularly springy and sturdy. The major problem was that yew was not a common tree and was relatively rare in England. Because of this, they were sometimes made of elm or ash.
Staves were selected with great care and went through a relatively long production process. Oil and wax were applied to the stave to make it waterproof and help preserve it. It had to be relatively thin, and the length would be customized to the archer. The longest measured about six feet four inches, with shorter ones somewhat over five feet. Since there was a direct correlation between the bow length and the power it could generate, the longer the bow, the better. It was usually about two inches across at its thickest part. The force required to pull a longbow back to its maximum extension ranged from about eighty to one hundred twenty pounds. The draw length was from twenty-nine to thirty-two inches, and it was soon determined that it worked best when the bow was drawn back to the eye.
Arrows were made of a variety of woods. Aspen, poplar, elder, willow, and birch were all used, with the average length of an arrow being about three feet. It was determined early on that feathers along the side helped to stabilize the arrows in flight, and the feathers were usually seven to nine inches long, and glued to the shaft. The bowstring was usually made from hemp, but later on flax and silk were used.
One of the major problems with the longbow was the training required to master it. Because of the tremendous force required to pull it back, considerable practice was required to use it effectively, particularly in battle. As a result, English boys usually began their training by about age seven. They were trained extensively, and tournaments were held in all villages, with the best archers being selected for the military. And it was a great privilege to serve as a military archer, as the archers were considered to be members of an elite group.
The average trained English archer could fire at least twelve arrows a minute and hit targets at two hundred yards. Indeed, if you could fire at a rate of only ten arrows a minute you were considered a poor archer.
We looked at the physics of the bow and arrow briefly earlier, and much of what we said also applies to the longbow. We'll consider it in more detail, however. The physics involves both the mechanics of the bow and the flight of the arrow. As we saw, when the archer pulls back the bow he does work that is stored as potential energy. When the string is released this potential energy is converted to the kinetic energy of the arrow. Actually, some of the potential energy goes into the final motion of the bow (a slight vibration), but it is usually a small portion. It is important to note that the farther the string is pulled back for a given bow, the greater the potential energy. This is why the longbow was able to impart more kinetic energy to the arrow. It is longer and can therefore be drawn back farther.9
The range, or distance, the arrow travels, depends on the following things:
Initial velocity
Weight of the arrow
Angle at which the arrow is shot
Air resistance
Effect of the wind
The arrow's initial velocity can be determined by equating the potential energy (F × d) of the bow (with the string pulled back) to the kinetic energy of the arrow (1/2 mv2, where m is the mass of the arrow). The angle at which the bow is pointed has a strong bearing on its flight path, or trajectory, and how far it will go. It's relatively easy to show that the greatest range is obtained an angle of forty-five degrees if air resistance and wind are not taken into consideration. But as we will see later, these varia
bles are also important, and they do limit the range.
The path of the arrow is a parabola. This is the curve seen in the headlight of a car. But because of air resistance, it can be a slightly distorted parabola. Air resistance creates a force on the arrow that slows it down; this is the result of a transfer of some of the momentum of the arrow to the air. There are two types of drag on the arrow: sheer drag and form drag. Sheer drag occurs because the arrow drags the air adjacent to it along with it as it moves. Indeed, if you could closely examine the arrow in flight, you would see that there is a series of layers of air around it, with the layer closest to the arrow being dragged the most, the second layer being dragged to a lesser degree, and so on. Sheer drag is proportional to the velocity of the air moving past the arrow.10
Form drag occurs because sheer drag causes eddy currents behind it. These eddy currents form a turbulent wash behind the arrow in the same way that a speedboat creates a wash when it moves through water at high speed. And the faster the arrow goes, the greater the turbulence and the greater the form drag. Mathematically, form drag is proportional to the square of the velocity (v2). It acts in a perpendicular direction, pushing the arrow to the side and creating frequency oscillations during its flight.
Furthermore, when an arrow is released, it creates a perpendicular kinetic energy. For a right-handed archer, when the arrow is released the string moves slightly to the left, causing the arrow to bend to the right. Then the string moves back to the right, causing the arrow to move left. All this happens in the brief time that the arrow is still attached to the string. But when the arrow leaves the bow, this slight right-left vibration continues through the flight. If the archer is left-handed, the vibration is opposite.
The amount of vibration depends on the stiffness of the arrow. If it is quite flexible it will vibrate excessively, which in turn will cut down on its speed and therefore its penetrating power. If it is too stiff, on the other hand, the arrow will not vibrate, and this affects its accuracy. So compromise is therefore needed.
The effective range of the longbow in the hands of early archers was generally about two hundred yards, and at that distance it could easily penetrate the chain mail armor used by most knights. Eventually, steel plates were placed over the chain for greater protection. But the longbow arrows could penetrate even the steel plates if the range was less than one hundred yards. The maximum range of the longbow was about four hundred yards. At the beginning of a battle, archers would usually shoot large numbers of arrows high in the air so that charging knights would encounter thousands of arrows falling from the sky. Later, as the charging knights got closer, the archers would select individual targets.
For years Genghis Khan, the leader of the Mongols, had been eyeing China. It was prosperous and thriving, and the Chinese had many things that the Mongols wanted and needed. In 1205, Genghis Khan decided to attack. It was little more than a raid, but it frightened and panicked the Chinese. The Mongols were cruel and well known for their use of terror; they took no prisoners and frequently wiped out entire villages.1
The Chinese had to do something, and they had to do it fast. They needed a weapon to counter the Mongols, and indeed they had something with considerable potential: a white powder that they were using in their fireworks.
Genghis Khan attacked again in 1207, causing even more fear. This attack spurred the Chinese to develop what would become known as the “fire lance.” It was a bamboo tube several feet long that had been drilled through the joints, with the bottom joint left in. The tube was wrapped to reinforce it and a small “touchhole” that could be used as a fuse was drilled near the lower end. White gunpowder was poured into the bottom, and arrows or other projectiles were placed on top of it. When the gunpowder was lit through the touchhole, the arrow left the barrel with considerable speed, but it only had a range of about ten feet. They also developed other weapons, such as simple flamethrowers, rockets of various types, bombs that could be thrown with a catapult, and land mines.
The Mongols declared full war in 1211 and swept down on horseback by the thousands, but the Chinese fought gallantly with everything they had. For two years the Chinese held them off, but eventually the Mongols overcame them, and soon they were using the new Chinese weapons against others.
Over the next few decades the art of war changed significantly. A revolution had begun, but at this time no one realized how important gunpowder would eventually become in warfare. To tell the entire story, however, we have to begin with the discovery of the components of gunpowder, one of the most important of which is saltpeter. Saltpeter is actually potassium nitrate, and at the time of the Mongol invasion it was relatively rare in China. One of the first places it was found was on the walls of caves, where it could be scraped off as a white crystalline powder. It generated interest because it flamed up when sprinkled on a fire. Later it was also found on the floor of stables that housed horses. Alchemists showed that it came from the urine of horses.
Genghis Khan.
The biggest problem with the early form of saltpeter was that it was actually a mixture of potassium nitrate and calcium nitrate. Techniques for improving its purity were developed over the years by alchemists, and they eventually became interested in it as a possible elixir of immortality. In the early 800s, however, they began mixing it with other chemicals. A mixture that soon began to attract interest was the mixture of saltpeter, sulfur, and carbon (in the form of charcoal). When rolled in paper and set on fire it caused a loud explosion, and as a result it was soon used in celebrations and to scare away evil spirits.
The Chinese alchemists no doubt started with a 1:1:1 mixture of the three materials, but they eventually found that a 4:1:1 mix (with the 4 corresponding to saltpeter) gave a much better explosion. As it turned out, saltpeter was the oxidizer in the combination (so it didn't need air to explode), with sulfur and carbon acting as fuels. The ratio between the three components was, indeed, critical, and it was later found that different ratios yielded even greater explosions. For gunpowder, however, the three major components remained the same.
For a few hundred years after the discovery of gunpowder there is no indication that the Chinese used it for anything but celebrations and as “toys” for children. But all that changed when the Mongols attacked. At first they overcame a few villages in the north, but finally they not only conquered all of China, but also continued on their rampage throughout Europe, eventually capturing most of it. And not only did they use the new Chinese weapons, but they developed others and used them in their further conquests.2
News of the new weapons spread rapidly. By 1250 the Arabs had begun to use gunpowder in a simple “cannon” they called the madfaa. It consisted of a wooden bowl or pot that was packed with gunpowder, with arrows or other projectiles such as stones above it. When the fuse was lit the arrows or stones would fly in the general direction of the enemy. Needless to say, the madfaa was very inaccurate.3
ROGER BACON
The news of the strange new explosive eventually reached England in the mid-1200s, and an English philosopher and Franciscan friar named Roger Bacon heard about it. A trader or missionary brought him a “firecracker” that had been made in China. Bacon had a strong interest in science; indeed, he eventually made significant contributions to many branches of science and mathematics, including optics and astronomy. Furthermore, he had a relatively good knowledge of chemistry. He took the firecracker carefully apart and examined the powder inside. Analyzing it, he found it to be made up of saltpeter, sulfur, and charcoal, and it didn't take him long to realize it was an important mixture that could have significant application in war. He worried that it might get into the wrong hands; nevertheless, he mentioned the discovery in his book Epistolae de Secretis Operibus Artis et Nature et de Nullitate Magiae a few years later, though he was reluctant to publish the exact formula for it. It is said that he finally decided to publish it in the form of a cryptogram, but others have disputed this.4
One of the problem
s with gunpowder at this stage was that it depended critically on saltpeter, and Bacon soon discovered that the saltpeter in the mixture was impure. He therefore made a study of it and found a way to purify it.
While Bacon was making his discoveries, the Chinese were still working on their weapons. Within a few years they had developed a crude form of a cannon, but at this stage it was difficult to use and dangerous when fired. And, of course, their crude cannons were terribly inaccurate. They noticed, however, that if the explosive gases were contained in a fireproof and blast-proof chamber, the resulting “explosive power” was significantly increased.
Evidence that the Chinese were working on gunpowder came in 1280 when a large gunpowder arsenal caught fire. The resulting explosion was heard for miles around, and it was reported that over one hundred guards were killed in the explosion. Furthermore, pieces of the storage building were found over two miles from the explosion.
DEVELOPMENT OF THE CANNON
Crude early cannons were made by the Chinese, the Arabs, and the Mongols, but the first cannons as we know them appear to have been built in Germany and Italy. The name cannon, incidentally, comes from the cylindrical barrel of the device; the Latin word for it is canna. The Latin word canon was also used later to mean “gun.”5
An early Chinese hand cannon.
The first English cannon appeared in 1327, and there is some indication that the German Berthold Schwartz (sometimes called “Black Bart”) mixed up the ingredients of gunpowder about this time and may have made a simple cannon. According to folklore, he put his mixture in a pot and covered it with a large stone slab, and somehow a spark ignited it and blew the large slab through the roof of his laboratory.6