Quiet Cannons: Mechanical Artillery

^{A type of siege engine the Romans called an “onager.”}

To King Archidamus of Sparta it seemed that his whole world had turned upside down. This was odd because troops had just arrived from Syracuse in Sicily to help him in one of his campaigns.

A Sicilian officer had demonstrated an invention that the Syracusians had used successfully against Carthage. The weapon was a giant bow mounted on a wooden stock. The stock was in two pieces: The top piece slid in a groove cut in the bottom piece. The Syracusians had attached the bowstring to the slider with a catch, then pulled both slider and bowstring back with a winch (a crank or handle). The bow was obviously far too powerful for a man to draw without the aid of machinery. On the sides of the slider were pawls that clicked into ratchet notches on the bottom stock as the slider was pulled back. When the slider had clicked into the last notch, a Syracusian soldier pulled a cord that released the catch. The heavy arrow flew many times farther than any archer could have sent it. The Sicilians reloaded their weapon and shot another arrow at a shield and a corselet. The missile went entirely through all the armor.

The Syracusian officer smiled proudly at the king, expecting praise for the ingenuity of the scientists of Syracuse and gratitude for bringing this powerful new weapon to his aid. Instead, the king was shocked.

“By Heracles,” he said, “this is the end of man’s valor!”

To most Greeks at that time, around 370 B.C., war was a slugging match between masses of shield‑carrying, armored warriors. Valor in battle was the high‑est virtue for all Greeks, especially for the Spartans. Each Spartan man devoted his whole life to only one thing: becoming the bravest, strongest, most skillful hand‑to‑hand fighter he could be. Now it was possible for a puny coward with one of these machines to kill the bravest and strongest soldier who ever lived.

The Spartans were not enthusiastic about the new weapon, and most Greeks agreed with them rather than with the Syracusians. Syracuse, a colony of Corinth, was relatively young for a Greek city and even younger as a major power in the Greek world. Its destruction of the Athenian expedition sent against it during the Peloponnesian War was quite unexpected. The ancient traditions of hoplite warfare had less hold on the people of Syracuse than on those of mainland Greece.

Moreover, Dionysius, the tyrant of Syracuse, was a man of imagination. Dionysius aspired to lead all the Greek cities of Sicily against the powerful state of Carthage, which had established colonies on the western end of the island. He recruited designers, mathematicians, and craftsmen from all over the Greek world, offer‑ing high wages with prizes for outstanding work on new weapons. For stars, there were places at his table. The leading engineers flocked to Syracuse.

One of their inventions was the gastraphetes, a type of crossbow with a kind of half‑hoop fixed at the end of the stock. To cock it, a man put the half‑hoop against his stomach and the front of the weapon against a wall or tree and pushed against it. The soldier was thus able to use the strength of his legs – far more powerful than his arms – to bend the heavy bow. The gastraphetes had the same sort of slider‑and‑rachet arrangement as the catapult shown to Archidamus. The next step was to build a much larger bow and cock it with a winch. The bow itself was of the ancient composite type, with a layer of sinew glued to a wooden core on the back, and a layer of horn glued to the core on the belly. When the archer drew a composite bow, the sinew was stretched and then snapped back.

At the same time the horn was compressed and then regained its length. The wood – a very thin strip – was flexible but added little to the bow’s power.

When the engineers had reached what seemed to be the limits of the composite bow, they began looking for a new type of spring. E.W. Marsden, who has studied all the ancient writings on mechanical artillery and built these machines by following the directions of the ancient engineers, believes they studied the elements of the composite bow – horn, wood, and sinew – and decided that sinew was the springiest element. So, they used the sinew in a new way.

They made cords of sinew and twisted them around the ends of two poles that were opposite each other on a wooden frame. The poles pivoted in their bundles of twisted sinew. Between the ends of the poles opposite the pivots was a cord that acted as a bowstring. The action was the same as that of the machine Archidamus saw, but instead of a flexible bow there were two inflexible poles powered by skeins of twisted sinew. Sometimes there wasn’t even sinew. Someone discovered that hair – human or animal – has the same kind of springiness as sinew, so many catapults were powered by ropes of hair.

The first catapults shot arrows (most of them long, heavy arrows that looked more like javelins) but others were made to shoot stones. These usually had a double bowstring with a pouch between the two cords to hold the stone.

It took the original Greek cities, such as Sparta and Athens, a while to really warm up to mechanical artillery, but the engines were adopted in a big way by King Philip II of Macedon. Like Dionysius, Philip scoured the Greek world for engineers and craftsmen. If the cord‑powered torsion catapult was not invented in Macedon, it was first used by Macedon on a large scale. In the middle ages, catapults were mainly siege engines, but Philip and his son, Alexander the Great, used them as field artillery, too. At one point in his march through central Asia, Alexander found himself blocked by the hither‑to invincible Scythian horse archers who were on the other side of the Jaxartes River.

Alexander lined up all his artillery on his side of the river and, according to the historian Arrian, “the machines kept firing salvos at the Scythians riding along the bank, some of whom were wounded by the missiles and one, stricken right through his shield and breastplate, who fell from his horse. Thereupon, terrified by the range of the missiles and because a noted warrior had fallen, they retired from the bank a little.” And Alexander’s army crossed the river.

The ancient field artillery obviously had a psychological effect even stronger than the physical effects it was capable of causing. The history of warfare is full of psychological weapons (weapons that induce a disproportionate fear).

Among them are the cavalry lance, the bayonet, the submachine gun, and the dive bomber.

Mechanical artillery was always useful in sieges. The arrow‑shooting catapults made it possible to shoot defenders off a city wall from well beyond the range of their bows. Stone‑throwing machines could knock down inferior stone walls or could shoot over the walls to demolish houses and other buildings inside.

The engineers continued to improve their machines’ accuracy and durability. The Romans used small catapults, called carroballistae, mounted on wheels with the skeins of cord enclosed in metal cylinders to protect them from moisture. The Romans also invented a new stone‑thrower called an onager, which had a single upright arm mounted in an enormous skein of cord. The top of the arm was either shaped like a scoop to hold the stone or the stone was placed in a rope sling at the top of the pole. Roman artillery, like that of Philip and Alexander, was used for both sieges and field battles. Every century in the army (the smallest unit) of the Roman Empire had an artillery piece.

The dark ages that followed the fall of Rome created a temporary hiatus in the development of mechanical artillery in western Europe. Later, when warfare was dominated by armored knights, the powers that be had no incentive to develop field artillery that could mow down mailed horsemen. Sieges were another matter, though. The catapult and the onager were revived and played a prominent part in attempts to capture castles. During the Crusades, the Muslims used their mechanical artillery to throw barrels of flaming naphtha at the Crusaders. The Christian warrior soon adopted this fiery weapon.

The Middle Ages also saw the adoption of a new siege engine in Western Europe. It was called a trebuchet. It was a pivoted beam, heavily weighted on the short end. The long end was tipped with a sling, into which a missile was placed.

The long end was hauled down and loaded. When it was released, the weighted short end fell, and the long end swung up and shot the missile at the enemy stronghold. The trebuchet was probably copied from the Chinese huo‑pa’o, which had been adopted by the Mongols and carried west by them.

The trebuchet’s power was limited only by its size. In the Middle Ages, some trebuchets were used to throw dead horses into a besieged city to spread disease. Modern experimenters have built trebuchets capable of throwing an automobile several hundred yards. Around the turn of the last century, Sir Ralph Payne‑Gallwey built smaller versions of some mechanical artillery. He found that an onager equipped with a sling could throw an eight‑pound shot almost 500 yards, and that a catapult with two arms powered by twisted cord, he found, would shoot a 5 or 6 pound spear 500 yards. The same catapult, equipped to shoot stones, would shoot a 1‑pound shot 350 yards. Payne‑Gallwey did not attempt to make a trebuchet, but he noted that the French Emperor Napoleon III built one with a 33‑foot beam and a counterpoise of 10,000 pounds. Napoleon’s trebuchet shot a 50‑pound cannon ball 200 yards, but, Payne‑Gallwey wrote, that it was “so lightly constructed that its full power could not be safely applied.”

In the Hellenistic world, during the heyday of mechanical artillery, the mere existence of these machines was a potent factor in international relations. According to Dr. Serafina Cuomo, a British historian of science quoted in the New York Times, “You didn’t just have to have catapults to use them. You needed your potential enemy to know that you had them so they would not attack you in the first place.”

10 The Big Bang: Gunpowder

^{“Corned” gunpowder. The two top grains are pressed into special shapes. When gunpowder burns, the outside surface becomes smaller and gas pressure drops.}

^{The grain second from the top has a hole drilled into it so that as the outer surface decreases, the inner surface increases, helping the powder charge to maintain pressure in long‑barreled gun.}

Kublai Khan “ruled most of the world” – from the Yellow Sea to steppes of Russia. But, a true grandson of Genghis Khan, he wanted more. He had not yet finished the conquest of southern China when, in 1274, he sent an army and a fleet to subdue Japan. The fleet was manned by Korean sailors and carried 40,000 Mongol soldiers. They were greeted by 120,000 Japanese samurai. The Mongols had the powerful central Asian composite bow, but their opponents were no mean archers. The Japanese had their unique longbow, which was a good match for the Mongol weapon. But although the Japanese outnumbered the Mongols three to one, Kublai’s men pushed the islanders back. One reason was their discipline and training. The Mongol army was organized on a decimal basis: squads of 10, companies of 100, regiments of a 1,000, and divisions of 10,000. All units responded to orders given by the beating of kettle drums and the waving of standards. And at this time, the Mongol armies were the most experienced in the world.

Fortunately for the Japanese, a typhoon swept up the west coast of Japan and wrecked most of the Mongol fleet. The Mongol commander took what was left of his army and armada and returned to China.

Kublai Khan did not give up easily. In 1281, he sent another expedition to Japan. This time, there were 150,000 soldiers. Again the Mongols pushed the Japanese back, but resistance was stiffer this time. The Japanese had built a high stone wall around the area on Kyushu where the invaders had first landed.

That turned out to be where they landed the second time. The Japanese brought up a huge crowd of samurai warriors, but they were barely able to hold the wall.

During the night, though, they raided the Mongol camp. They attacked the invasion fleet with small boats and managed to set fire to some of the Mongol ships. The Japanese resistance stalled the Mongols for seven weeks. The Mongol commander decided to move his fleet, and then another typhoon struck.

Approximately 4,000 Mongol ships were sunk, and more than 30,000 Mongol troops were drowned.

To be saved from a Mongol invasion twice by typhoons seemed to be more than a coincidence to the Japanese. The decided they had been saved by the gods, who sent the Kamikazes, the divine winds, against their enemies.

The Kamikazes also left conclusive proof of one reason for the Mongols’ success before the storms arrived. Recent exploration of the sunken wrecks of Kublai Khan’s warships disclosed ceramic pots filled with gunpowder. Similar pots with ignited fuses had been shot from mechanical artillery against the Japanese defenders. Japanese tradition also maintains that the Mongols shot rockets at the samurai soldiers, and old Japanese paintings show defenders being attacked by exploding bombs.

At the time of the Mongol expeditions to Japan, gunpowder was known in Europe – Roger Bacon’s famous manuscript was written in 1252 – but there’s no record of it being used. For years, it became something of a cottage industry among some Western scholars to prove that gunpowder was not invented in China, but the evidence was mostly negative – neither Marco Polo nor Giovanni di Plano Carpini mentioned seeing gunpowder in China; therefore it was not there. But the wrecked Mongol ships prove that gunpowder was in use, and a standard weapon, in the mid‑13th century. And the medieval Arabs, who probably had gunpowder before the Europeans, referred to potassium nitrate, the key ingredient, as “the snow from China.” Further, evidence that gunpowder was known in Europe appears immediately after the Mongol conquerors of northern China galloped into Europe.

Early Chinese writing records the use of what could only be gunpowder.

Why was there so much doubt about the Chinese?

Besides an enormous ethnic bias on the part of many Westerners, it seems the Chinese did not consider gunpowder a particularly important weapon. From about 1000 A.D. it had been mostly used for firecrackers. Martin van Creveld, in his Technology and War, points out that in the 12th century, the Chinese were using crude hand grenades. These were paper and bamboo tubes filled with gunpowder and pebbles or bits of broken porcelain. After another century, they had bamboo guns (devices like the bamboo grenades, but open at one end). Though, like the rockets and ceramic bombs the Mongols brought to Japan, none of these weapons were considered serious weapons. The gunpowder was weak, and so were the shells in which it was exploded. The bombs and rockets were mostly useful in scaring horses – or troops like the Japanese who had no experience with gunpowder.

Lieutenant Colonel H.W. Hine concluded, after much study, that the Oriental gunpowder used unrefined potassium nitrate, which made it impossible to get a powerful explosion.

The first written directions for refining potassium nitrate are in Roger Bacon’s letter to the Bishop of Paris. There was great interest in the process in Europe but little anywhere else. Warriors in medieval China ranked just above thieves in popular esteem. Nobody in power felt any need to develop more potent powder. The Mongols’ scientific tradition was non‑existent. Besides, they were sure they had the ultimate weapon: the horse archer. And, until after guns had developed for several centuries, the Mongols were right. The Arabs and Turks also had complete faith in the supremacy of the horse archer.

In western Europe, however, the desire for better weapons was keen. The Crusades had demonstrated to the Europeans that they could not compete with horse archers on the open steppes. Nor, in their damp, forested homeland, could they develop effective horse archers of their own. But there was a continuous search for better weapons among warriors who never dreamed of leaving their homeland. Europe was a quarreling mass of dukedoms, principalities, and city‑states. It was inhabited by armed nobles, armed townsmen, and armed mercenaries, all of whom were trying to find some weapon that would trump everyone else’s. Consequently, Europe developed the first effective guns. The Chinese learned to improve their guns only after they’d examined European models.

Japan, voluntarily cut off from the rest of the world, ignored guns completely until the 16th century. Then, for a short time, Japan had more handguns – but little artillery – than anywhere else in the world. Guns, however, let a low‑born peasant who couldn’t even recognize a good sword kill any samurai master of swordsmanship. Therefore the samurai, who controlled Japan, stopped all development and most manufacturing of guns.

Europeans, on the other hand, not only adopted gunpowder, they continued to improve it. They increased the proportion of potassium nitrate to make a more powerful explosive. Then, because the three components of the mixture tended to separate, they mixed them wet and formed them into “corns,” which could not separate. Near the end of the gunpowder era, they molded the “corns”

into various sizes depending on the size and mission of the gun. Some were made with a hole through them to produce a powder than gave consistent gas pressure. As the outside of a corn burned, the surface decreased, causing pressure to drop. But as the inside of hole in the corn burned, the surface increased, producing more gas and raising the pressure. All this “burning,” of course, happened in about 1/100,000 of the blink of an eye.

Guns were not the only use of gunpowder. One use gave new life to one of the earliest techniques of siege craft.