The Physics of War (2 page)

The first well-documented battle in the history of the world took place in 1457 BCE on the Plain of Esdraelon, near the city of Megiddo in modern day Syria. It is usually referred to as the Battle of Megiddo. Megiddo, along with several other cities in the region of Palestine and Syria, had formed a coalition under the Prince of Kadesh, and had decided to break away from Egypt. Egypt's pharaoh, Thutmose III, was determined to stop the rebellion. With an army of ten thousand to fifteen thousand men, including infantry, archers, and cavalry, he marched toward Megiddo, arriving within a few miles of it in April. As the army camped at a place called Yaham, Thutmose conferred with his generals. There were three routes from Yaham to Megiddo; two were relatively easy, but a third, more direct route through the mountains, was quite difficult. Part of the route passed through a very narrow pass where his soldiers would have to travel single file. In addition, the cavalry would have to dismount and lead their horses. Strung out in this way, they would be vulnerable if the Prince of Kadesh decided to attack. Thutmose's generals encouraged him to take one of the easy routes. As he thought about it, however, he realized that the Prince of Kadesh and his troops would not expect them to come through the mountains because of its difficult terrain. They would likely be waiting at some point along the other two routes. So, to the disappointment of his generals, he decided to take the route through the mountains.
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And indeed, Thutmose was right. The Prince of Kadesh's men were waiting for them at the ends of the two easy routes. The prince had split his army into two groups, with one half of it in the south and the other half in the north. Furthermore, he had left almost no men to guard the city of Megiddo.

The following day Thutmose led his men through the treacherous pass, and when they broke out into the open, with the city of Megiddo directly ahead, they saw that it was lightly guarded. But Thutmose didn't want to attack the city at this point. He still had to defeat the prince's army. It was late in the evening, so he camped overnight and was ready for battle the next morning. He split his men into three wings and moved quickly to attack the flanks of both sections of the
prince's army. They were so surprised by an attack coming from an unexpected direction that most of the men broke rank and fled. Most of them ran for the shelter of the city.
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Thutmose pursued them, and by the time he got to the city he could see that many of them were trapped. The defenders of the city had seen the fleeing men coming and had opened the gate, but as Thutmose's army came into view they immediately shut it, leaving many outside. The citizens inside, however, acted quickly; they lowered ropes made of clothes to pull the stranded soldiers over the walls.

Thutmose wanted to attack the city, but by now most of his soldiers were plundering the enemy camp, taking whatever they could find. By the time he got his army reorganized most of the enemy, including the Prince of Kadesh, were safe in the city, which had a high, strong wall all around it. Thutmose could see that it would be suicidal to attack it directly, so he decided on a siege. His troops had plenty of supplies, and there were more supplies available in the surrounding area. But the people within the city were cut off, so it was only a matter of time before they ran out of food and other supplies. The siege lasted for seven months, but finally the citizens and what was left of the army surrendered. By this time, however, the Prince of Kadesh had somehow escaped.

It had taken longer than he had hoped. Nevertheless, Thutmose had soundly defeated the prince's army, and he had captured Megiddo.

SUMMARY OF THE BOOK

Like all rulers or generals going to war, Thutmose III was looking for something that would give him an advantage, and he found it. In his case it was a tactic that gave him an element of surprise. Throughout history, and even today, military leaders contemplating war, or involved in it, are still looking for some sort of advantage over their enemy. Whereas Thutmose used a surprise tactic to his advantage, throughout most of history military leaders have searched for a new “wonder weapon”; in essence, a weapon the enemy does not have. As we'll see in this book, it is usually physics that provides a path to this new weapon. Physics and science in general has indeed been of tremendous value to military leaders. It has given them a better understanding of ballistics so that they can aim their guns better; it has given them radar so that they can detect the enemy before they are detected; it has given them an understanding of the electromagnetic spectrum so they can use radiation in various military applications; it has given them an understanding of rocketry and jet engines, and an understanding of the secrets deep within the atom so they are able to build super bombs.

This book gives an overview of most branches of physics, and it shows how they are used for military applications. It also gives a summary of the history of war all the way from the first bows and arrows and chariots through to the atomic and hydrogen bombs. We begin in
chapter 2
with the Egyptians, Assyrians, and early Greeks. We'll look at some of their interesting weapons, such as the ballista, the onager, and the trebuchet, all of which involve basic principles of physics.

In
chapter 4
we look at the rise and fall of the greatest military establishment ever seen up to that time, namely the Roman Empire. The early English-French battles are also included in this chapter; one of the most famous of these was the Battle of Agincourt, where the English used the longbow to overcome a much larger and more powerful army. It was their secret new weapon.

In
chapter 5
we see the introduction of new technologies that completely changed the nature of war: gunpowder and cannons. Cannons were, in fact, so effective that they led to wars that lasted for a hundred years. At this stage, however, we can't say that physics made large contributions to the art of war because, for the most part, it didn't exist. But as we'll see in
chapter 6
, three men, including Galileo, made important advances and helped put physics on a much better footing.

With these advances and others, war became even more prevalent throughout Europe. Rifles improved significantly, beginning with the matchlock and ending with the flintlock a few years later. In addition, ships were now getting larger, and they were soon equipped with cannons. Furthermore, with William Gilbert's discoveries in relation to magnetism came a better understanding of navigation at sea, so sailors could now head out into the unknown without worrying about getting lost.

Then came the magnificent discoveries of Isaac Newton, and physics was raised to new heights of understanding. His discoveries are discussed in
chapter 7
. Following this came the Industrial Revolution, discussed in
chapter 8
. In a period of less than one hundred years the civilized world changed significantly. In particular, several new techniques, including mass production, made war even more devastating.

In
chapter 9
we look at Napoleon and his weapons and tactics. Without doubt, he is one of history's greatest military tacticians, but strangely he didn't introduce many innovative new weapons. About this time another revolution in physics was occurring, and it would lead to a tremendous change in warfare. It began with the discovery that a “current” of electricity could be produced by a simple device called a pile. Soon the new phenomenon was all the rage throughout Europe, and it quickly attracted some of the best minds in physics:
Oersted, Ohm, Ampere, and Faraday. Electric generators, motors, and other electrical devices followed, and of course, they eventually became central to war.

In
chapter 10
we come to the American Civil War, which was the most devastating war ever fought on American soil. By this time tremendous advances had occurred, including the percussion cap, which quickly led to much more accurate and deadly rifles, along with the first use of submarines, balloons, and the telegraph in warfare.

In
chapter 12
we discuss the airplane. World War I erupted only a decade after the first flight of the Wright brothers. And it didn't take long before airplanes were used in the war. “Dogfights” were soon common, and the airplane has played a central role in warfare ever since. Many other new weapons were also developed in World War I. They included huge new cannons, the first tanks, poisonous gas, and flamethrowers.

Soon after World War I radar was developed, and it would eventually play a central role in war. Along with it came a significant improvement in submarines, and the use of sonar. Submarines would be very effective for the Germans in World War I and at the beginning of World War II.

Then in 1939 came another, even greater war, namely World War II, which produced phenomenal new weaponry. These developments included important advances in radar, the first jet airplanes, the first rockets, the first large computers, and of course, the atomic bomb. All of these will be discussed.

Finally, in the
last chapter
we will discuss the hydrogen bomb and some of the possible weapons of the future.

As we will see throughout the book, every era had its “wonder weapon,” and one of the earliest was the chariot. Pulled by two or three horses, chariots allowed warriors to move at tremendous speed. The chariots were usually manned by a driver and an archer equipped with a large number of arrows. Fast-moving chariots would crash into the infantry of the enemy while the archer fired arrows, frequently causing panic. Like our tanks of today, the chariot became a major weapon of early armies. Soon thousands of them were involved in the battles of the day.

BATTLE OF KADESH

One of the largest chariot battles the world had seen occurred in 1274 BCE near the village of Kadesh (in present-day Syria). More than five thousand chariots were involved. A large Egyptian army was led by twenty-five-year-old Ramses II. He was brash and confident but had little experience. Against him was a Hittite force led by Muwatallis II, who was a veteran of many wars and had considerable experience. Ramses led a force of about thirty-five thousand men, which included about two thousand chariots and a large number of archers. The Hittite army consisted of over twenty-seven thousand men and close to three thousand five hundred chariots. The Egyptian chariots accommodated two men, and they were much lighter, faster, and more maneuverable than the Hittite chariots, which were built to accommodate three men.

Ramses commanded four divisions, each of which was named for an Egyptian god: Amun, Re, Seth, and Ptah. He also had another division of mercenaries called the Ne'arin. With Ramses in the lead, his army began a month-long march toward Kadesh. When he was about seven miles from it, his men came upon two Bedouins, or nomads, who claimed they had been conscripted to serve in the Hittite army but had escaped. Ramses questioned them and was pleased
when they told him that Muwatallis's army was 135 miles away in a place called Aleppo. Furthermore, they said Muwatallis was afraid of Ramses and his army.

This made Ramses even more confident, since it meant he would be able to capture Kadesh without having to fight the Hittites. Without verifying the story he quickly pushed on. Indeed, he was in such a rush that he and his bodyguards had soon outdistanced most of his troops. Close to his destination was the Orontes River, which was difficult to cross in most places, but it could be crossed close to Kadesh. Ramses and his small contingent of guards splashed their way across it, then moved through a wooded area to a clearing, from which he could see Kadesh. He decided to set up camp, and within a short time his Amun division caught up with him, but his other divisions were still relatively far behind.

As the men were setting up camp his guards brought two captured Hittite soldiers before him. Ramses began questioning them, but they refused to talk. Only after being beaten did they finally confess, and what they had to say shocked Ramses. They told him that the Hittites were massed behind the old city of Kadesh with infantry and chariots, and that they were more numerous than the grains of sand on the beach.

Ramses could hardly believe what he was hearing. The two Bedouins that he had talked to earlier had been lying, and indeed Muwatallis had sent them to set a trap. Ramses was now only a few miles from Kadesh, and he had only half his army with him. The Hittites were no doubt ready to attack. Ramses sent messengers to the lagging divisions telling them to hurry. He knew that the Ptah division was not far away, however, and with it he would have three-quarters of his army, so he wasn't worried.

Muwatallis, meanwhile, had divided his troops into two main forces. One was to strike at the rear of the Egyptian army; the other, which included Muwatallis, himself, along with a force of one thousand chariots and a large contingent of infantry, would strike from the side, preventing the Egyptians from retreating.

The Hittite chariots spread into formation, then they attacked. The Re division, straggling behind, had just emerged from the forest into the clearing area. Twenty-five hundred Hittite chariots ripped into it; the Egyptians didn't know what hit them. Panic raced through the survivors as the Hittites slaughtered most of them. The remnants of the division ran toward the safety of the main Egyptian encampment, but the Hittites followed. Ramses was surrounded by his guard, which consisted of the best-trained troops in his army. The Hittite charioteers rushing toward him proved no match for the well-trained guards, who quickly killed large numbers of them.

Ramses had been busy reaming out his officers when the attack came, but he quickly took charge, and with what remained of his army he counterattacked. He did, however, have several advantages: his chariots were faster and could easily outmaneuver the Hittite chariots. Furthermore, his archers had a relatively powerful composite bow, and within a short time they had inflicted severe damage on the Hittite forces.

Strangely, the Hittite infantrymen, who were sure the battle was almost over, stopped and began looting the Egyptian camp. As a result, they became easy targets for the Egyptian counterattack. They were soon routed, with many of them dead on the field. The battle, which had started out as a slaughter for Muwatallis II, was now turning in favor of the Egyptians. Nevertheless, Muwatallis ordered another attack. In the meantime, Ramses' Ne'arin troops arrived, bringing his army to nearly full strength, and it counterattacked with everything it had. Soon the Hittites were overwhelmed, and many of them fled back toward Kadesh.

But Muwatallis II was not ready to give up. Most of his chariots, however, were now on the opposite side of the Orontes River. They had to cross it to attack the Egyptians. Ramses looked over the situation and decided to let them attack; he had a plan. He let the Hittite chariots cross the river, knowing that as they started up the steep bank toward the Egyptians they would slow to a crawl. When they did, Ramses ordered his chariots to attack, and they soon pushed the Hittites back into the water, inflicting heavy losses.

Muwatallis then ordered another charge, and again his troops were driven back, this time with even heavier losses. For the next three hours, in fact, Muwatallis continued the same tactic, until most of his officers were gone and many of his charioteers had been killed, many by drowning. Finally, when the Ptah, the last of the Egyptian divisions arrived, Muwatallis decided it was hopeless. He and his troops retreated, many to the safety of Kadesh, with others continuing on to Aleppo.

Ramses had also lost a lot of men by this time. He decided not to attack Kadesh and instead returned to Egypt. Both leaders claimed they had won the battle, and, indeed, Ramses had routed the Hittites, but he had not achieved his goal, namely the capture of Kadesh. Muwatallis, on the other hand, claimed he had stopped the Egyptians, and indeed, they had left.
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THE WONDER WEAPON

The chariot obviously played a large role in the Battle of Kadesh, and for many years thereafter it continued to be a major weapon of war. And certainly when it was first introduced it created terror among enemy troops. Most of the first chariots were built for two men, but later three- and even four-man chariots were used.

Most people are familiar with chariots from the movie
Ben Hur
, which starred Charlton Heston. It contained an exciting nine-minute chariot race that became one of the most popular sequences in the history of film, and it certainly gave viewers a good idea what it was like to drive or ride in a chariot.

An early war chariot.

Although the chariot was initially a wonder weapon, it didn't take long before many armies had them. So of course a search soon began for a new wonder weapon. At the time, weapon designers couldn't turn to science because science didn't yet exist. Nevertheless, the search was on for a new weapon that would shock and terrorize the enemy. Indeed, the process soon became an endless cycle.

COPPER, BRONZE, AND IRON

Wonder weapons had, indeed, already appeared. The earliest weapons were no doubt wooden spears and sharpened knives made of stone, but about 5000 BCE men in Persia and Afghanistan began to find strange lumps that could be hammered into various shapes, and they soon discovered that the material could be melted at a relatively modest temperature. It was what we now know as copper, and it would soon play a large role in the lives of the people of the time. Copper could be molded or cast into many different shapes. But it was soft, so knives made of copper would not keep a sharp age. Something harder was needed, and perhaps by luck, or perhaps by extensive experimentation, it was discovered that when a softer metal, tin, was added to copper in a molten state, the result was a new metal, bronze, which was considerably harder than either copper or tin alone. Bronze was soon used for knives, spears, and other weapons that needed sharp edges.
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The science of metals, or metallurgy as it came to be called, soon came into its own. Axes, daggers, shields, and even helmets were cast from bronze, and they soon became the new wonder weapons of war. For years however, people had been aware of a red-brown mineral that could be found near the earth's surface, and it was eventually discovered that it could be mined and smelted into another new metal, iron. It's hard to say exactly when the Iron Age began. Iron had been observed as early as 3000 BCE, but it took until about 1200 BCE before suitable smelting techniques developed. Iron smelting is much more difficult than copper smelting because of iron's higher melting point. Furthermore, when it was first obtained in a relatively pure form, it wasn't much harder than bronze, but then it was discovered that if carbon was added to it, it became much harder.

One of the things that may have spurred the search for a better metal than bronze was that tin was relatively rare, and shortages frequently occurred. Another reason was that states that could not afford to build thousands of chariots needed weapons that could match the dominance of the chariot. Infantry was no match for chariots, but some leaders began to believe that with the proper weapons it could be. And as metallurgists learned more and more about iron, and how it could be strengthened with carbon, much longer swords and spears came into existence along with iron shields that arrows could not penetrate. And with them, infantrymen could be equipped to stand up to chariots. With shields that could easily deflect arrows, and iron helmets to protect their heads, they could attack chariots with long iron swords and spears.

THE ASSYRIANS

The chariot was still a lethal weapon for many years, but a real breakthrough came when warriors on horses began to challenge them. Among the major enemies of the Assyrians were the nomads and barbarians of the north countries. Their life centered on horses, and they were particularly comfortable around them, usually learning to ride at a very early age. And it soon became obvious to them that a man on horseback, equipped with a bow or sword, had an advantage against chariots, since the mounted warrior was very mobile and could easily outmaneuver a chariot. He was high off the ground, and, with a horse under him, he was a formidable force; in addition, he was fast in a charge, even faster than a chariot.
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We now refer to forces of men mounted on horses as cavalry, but at that time they were not organized into what we would normally think of as cavalry. Nevertheless, they were effective. Early horse-mounted warriors didn't use saddles, but they were quite comfortable and stable without them. Stirrups came even later.

Mounted warriors from the north were highly effective in their frequent attacks on the Assyrians. It wasn't long, therefore, before the Assyrians began to develop their own cavalry. The Assyrians, who eventually became the most powerful empire of the region, were descended from the Akkadian Empire, which flourished near the upper Tigris River (near present-day Iraq) and lasted until about 2100 BCE. The Akkadian Empire eventually evolved into two states: the Assyrians in the north, and later the Babylonians in the south, but it was the Assyrians who first came to dominate the region.

During the early Assyrian years, the Bronze Age was in full swing and most weapons were made of bronze. Over the years the regional power of the Assyrians fluctuated, but there were two eras in which they were particularly powerful. Their early period of power and empire lasted from 1365 BCE to 1076 BCE. During this time their armies conquered most of the surrounding countries, including Egypt, Babylonia, Persia, Phoenicia, Arabia, and Israel. But after 1076 BCE Assyrian dominance ebbed. Then, in 911 BCE, the Assyrians once more began to grow in power. The Assyrian Empire eventually became the greatest military power the world had ever seen up to that time. Its resurgence was mainly due to Tiglath-pileser III, who ascended to the throne in 745 BCE.