Book summary “War! What is it good for?”: summary

Introduction

You live in a surprisingly peaceful era. Yet this peace exists because earlier generations waged devastating wars that forged large, orderly states. You find yourself torn between the obvious horror of armed conflict and its strange historical utility. Ian Morris tackles this paradox in War! What is it good for? through the story of Stanislav Petrov, who prevented a nuclear apocalypse in 1983, alongside Edwin Starr's famous anti-war anthem.

War is a horrific engine of destruction that has paradoxically served as the primary historical mechanism for forcing human cooperation and creating larger, safer societies.

The book guides you through a massive historical sweep to explain how violence built civilization. You explore four distinct parts covering deep primate biology and antiquity, the five hundred years of European conquest, and the nuclear and digital futures. Along the way, you confront difficult questions about the future of humanity.

• Why did early state formation rely on mass violence?
• How did the industrial revolution change the lethality and purpose of fighting?
• Can humanity survive the nuclear age without global government?

1. The Wasteland and the State

You might assume that ancient empires brought only tyranny and endless bloodshed. Tacitus recorded the speech of the Caledonian leader Calgacus condemning Roman imperialism as brutal destruction disguised as government and peace. In A.D. 83, roughly 30,000 Caledonians gathered under Calgacus at the Graupian Mountain to resist Roman expansion.

Ancient empires suppressed local feuds and daily violence by establishing strong central authority, functioning as stationary bandits who protected prosperous subjects to maximize long-term tax extraction.

The Roman general Agricola deployed auxiliaries and cavalry to crush the indigenous forces while sustaining minimal Roman casualties. Roughly 10,000 Caledonians were butchered by the Romans, while only 360 Roman auxiliaries and zero legionaries died.

Anthropological studies of small-scale societies reveal shockingly high rates of violent death compared to industrialized nations. While early anthropologists like Margaret Mead argued that human nature is peaceful and violence is a cultural contagion introduced by civilization, later researchers like Napoleon Chagnon documented severe levels of warfare, homicide, and feuding in indigenous groups.

Napoleon Chagnon documented among the Yanomami people of Venezuela and Brazil that approximately a quarter of men died violently and two out of every five men participated in a homicide. Across small-scale societies studied by anthropologists, 10 to 20 percent of people died violently. This contrasts sharply with the twentieth century, where 1 to 2 percent of people met violent ends across a population of 10 billion.

The Graupian Mountain

You can trace the evolution of rulers from roving plunderers into stationary bandits who promote local prosperity to maximize long-term tax extraction. Drawing on Mancur Olson's economic theory, Ian Morris explains that stationary rulers recognize the utility of suppressing internal violence, building infrastructure, and encouraging trade because protected, prosperous subjects yield more revenue over time.

King Uru'inimgina of Lagash proclaimed in a text from the 2360s B.C. that he freed his inhabitants from usury, murder, and seizure to establish freedom and protect the vulnerable. During the first two centuries of the Roman Empire, per capita consumption typically rose by 50 percent under the Pax Romana.

Stationary Bandits

You see this clear, hold, and build counterinsurgency strategy when Gnaeus Pompey successfully eliminated Mediterranean piracy. In 67 B.C., the Roman senate sent Pompey to crush pirates who infested Greek waters and had even begun raiding Italian harbors.

Instead of merely punishing captured pirates, Pompey divided the sea into 13 sectors, swept the outlaws away, resettled 20,000 ex-freebooters inland to farm, and established legal and financial administrative frameworks.

2. Caging the Beast

Population growth in agricultural landscapes caged human populations, triggering a Red Queen Effect of military innovations and state centralization that dramatically reduced violent death rates.

You can dismiss the idea of a unique Western way of war rooted in direct, hand-to-hand combat as a myth. A wider perspective shows that empires from Rome to China and India all independently developed disciplined armies, shock tactics, and laws that suppressed internal violence.

At the Battle of Plataea in 479 B.C., heavily armored Greek infantry defeated the unarmored Persian forces led by Mardonius. Scholars often cite this event and a 2,500-year timeline for the alleged Western way of war.

The Cage

The concentration of domesticable plants and mammals in specific temperate bands created the conditions for farming, population explosions, and the emergence of productive war. Global warming after the Ice Age favored large-grained grasses and meaty mammals in the lucky latitudes.

Humanity found immense biological raw material in these zones:

• out of approximately 200,000 species of plants in the world, humans can eat about 2,000;
• only 200 species possess genetic potential for domestication;
• of the 56 plants with edible seeds weighing at least ten milligrams, 50 originally grew wild in the lucky latitudes;
• of the 14 large mammalian species domesticated early, nine were natives there.

Population growth in agricultural landscapes caged human populations, making running away impossible after a defeat and forcing people into larger, more organized societies. Unlike hunter-gatherers who could simply move away after a conflict, settled farmers surrounded by other groups would lose everything if they fled.

In 58 B.C., when the farming tribe of Helvetii migrated into Gaul, the local Aedui could not simply run away. All surrounding land was occupied by other farming groups.

Military Revolutions

Military innovations such as fortifications and weapons triggered a Red Queen Effect, where societies had to continually run faster in organization and technology just to stay in the same place. When one group built walls or developed better weapons, rival groups responded by developing stronger siege tactics and counter-weapons.

In Sumer, as cities like Uruk built massive walls up to six miles long around 3100 B.C., the organization required to storm such defenses evolved just as rapidly.

Successive military revolutions involving bronze, chariots, composite bows, iron weapons, and cavalry periodically destabilized civilizations before forcing the growth of larger, more professional states. Innovations in weaponry and mobility changed the nature of combat from sporadic raids to massive, disciplined clashes.

At the Battle of Kadesh in 1274 B.C., thirty-five hundred chariots clashed in what was the biggest chariot battle in history. By 1208 B.C., Pharaoh Merneptah killed 9,274 warriors and captured 9,111 swords in a single campaign.

3. The Counterrevolution in Military Affairs

Counterproductive wars, steppe nomad incursions, and devastating plagues eventually overwhelmed ancient empires, plunging Eurasia into feudal anarchy before the gunpowder revolution broke the cycle.

Even successful wars of conquest eventually reach a culminating point. Beyond this threshold, expansion becomes counterproductive and reverses the benefits of empire. As empires pushed further inland away from cheap water transport, rising costs outweighed the gold and glory gained from conquest.

Between 11 B.C. and A.D. 9, Augustus attempted to expand Rome's frontier to the Elbe River. A disastrous ambush in the Teutoburg Forest cost twenty thousand Roman lives and three legionary standards, leading Augustus to advise keeping the empire within its boundaries. By the first century A.D., both the Roman and Han Empires ruled fifty to sixty million people across two million square miles each.

War Horse

Agrarian empires faced intractable asymmetric warfare when dealing with mobile steppe nomads. Because infantry could not force nomad cavalry to fight on their terms, empires used expensive preemptive expeditions, built massive containment walls, and paid protection money. Bribes often failed to keep nomads from raiding.

In 530 B.C., nomads killed King Cyrus of Persia and annihilated his army. In 200 B.C., Xiongnu nomads lured a Chinese army deep into the steppes and completely destroyed it. Emperor Wudi had 180,000 horsemen on his payroll in 110 B.C.

The success of productive war merged previously isolated disease pools across Eurasia, triggering devastating plagues that weakened empires and fueled collapse. As migration and trade connected civilizations, lethal pathogens met populations without protective antibodies. Egypt's population fell by a quarter between A.D. 165 and 200. Simultaneous outbreaks erupted on China's northwest frontier and in Roman military bases in Syria around A.D. 161 to 165, leaving forty-three emperors in Rome between A.D. 235 and 284, most of whom died violently.

Feudal Anarchy

Counterproductive wars drove a counterrevolution in military affairs that dismantled centralized states and plunged Eurasia into feudal anarchy. Unable to pay professional armies or collect taxes, kings traded land and privileges with local lords in exchange for military service. This created complex webs of crosscutting allegiances and decentralized violence.

In 1101, Count Robert II of Flanders swore fealty to King Henry I of England while already bound as a vassal to King Philip of France. Between 1200 and 1400, homicide rates soared until one person per one hundred was murdered across England, the Low Countries, Germany, and Italy. In England, one in 140 people was murdered, while nearly one death in six was a homicide in Italy.

The gunpowder revolution originated in China with the invention of true gunpowder and early firearms. Chinese chemists added saltpeter to create real gunpowder by the twelfth or thirteenth century, resulting in the oldest surviving genuine gun found in Manchuria in 1288. Officials in Florence were ordered to obtain guns and ammunition in 1326. While East Asian innovations slowed after 1350 due to the dominance of fast-moving steppe cavalry, Europeans continuously innovated by introducing corned powder, light cannons, arquebuses, and muskets. In 1494, French king Charles VIII used lightweight cannons to blow away Italian fortifications. Spaniards introduced muskets capable of piercing plate armor at a hundred paces in the 1520s, breaking the cycle of feudal anarchy.

4. The Five Hundred Years War

Between 1415 and 1914, European powers waged a five-century campaign of global conquest that ultimately suppressed local conflicts and drastically reduced rates of violent death in their core territories.

By 1914, Europeans and their colonists ruled 84 percent of the land and 100 percent of the sea. Although colonial conquest was often brutal and devastating for the defeated, conquerors suppressed local wars and banditry, making subjects' lives safer and richer through productive war on a global scale. Adventurers like James Brooke became the White Rajahs of Sarawak, while Josiah Harlan briefly became the prince of Ghor in central Asia by overawing opponents with disciplined troops.

Global Economy

Oceangoing ships transformed the Atlantic into an integrated intercontinental market, generating massive wealth through triangular trade while driving European overseas expansion. While maritime technologies like the compass were pioneered in Asia, European shipbuilders developed caravels, carracks, and galleons capable of oceanic travel. The Atlantic Ocean functioned as a Goldilocks Ocean—small enough to cross regularly and large enough to feature diverse ecologies—fueling a triangular trade of slaves, sugar, tobacco, and manufactured goods.

Christopher Columbus sailed west in 1492 to find a profitable route to the Indies, accidentally discovering the Americas and opening a vast new trade network. Vasco da Gama rounded the Cape of Good Hope into the Indian Ocean in 1498. Between 1500 and 1800, traders bought approximately 12 million people from warring African chiefs for shipment across the Atlantic.

Standardization and Drill

The standardization of weapons and the intensive drilling of soldiers and sailors transformed military personnel into interchangeable parts, maximizing the lethality of linear tactics. Invented by Dutch leaders and refined by Gustavus Adolphus, volleying allowed musketeers to fire continuously in staggered ranks rather than all at once. Achieving this required rigorous drill to turn human beings into cogs in a machine capable of executing complex routines under fire.

Count William Louis of Nassau wrote a famous letter in December 1594 outlining the countermarching volley technique inspired by Roman javelineers. A 1607 Dutch manual listed 43 separate steps involved in volleying. By 1696, France mustered 395,000 troops. You can see how tactical evolution turned armies into efficient engines:

• Form up six ranks deep and fire one rank at a time.
• The first rank fires, turns on heels, and marches back through the other ranks while the second rank fires.

The open-access economic order relies on the cooperation of an invisible hand of market forces and an invisible fist of state-backed violence to provide security and enforce rules.

Adam Smith argued in 1776 that economic growth stems from the division of labor driven by human self-interest. However, markets cannot function without governments establishing impartial legal frameworks, protecting property rights, and using force to keep threats at bay and secure international trade routes. Britain acted as a global policeman or globocop, using the Royal Navy to police sea-lanes and suppress the slave trade while fostering global commerce. From 1700 to the end of the century, Britain's exports grew from £2 million to nearly £40 million.

Industrial Revolution

The Industrial Revolution broke the iron law of wages by harnessing steam power to multiply manufacturing productivity and compress global distances. Facing high wages and flooded coal mines, British engineers developed steam engines to pump water and drive machinery. When steam power was applied to spinning machines, cotton production soared, lowering prices while stabilizing and eventually surging wages. Between 1786 and 1807, the price of spun cotton per pound dropped from 38 shillings to under 7 shillings.

The iron steamship Nemesis sailed from England for China in 1839, easily destroying Chinese junks and forts during the Opium War to demonstrate the overwhelming technological gap. Steamships and railroads subsequently demolished spatial barriers to trade and military projection.

As centralized states expanded and pacified their territories, domestic homicide rates and violent death rates experienced a massive historical collapse. Through the civilizing process, growing government enforcement of laws and the elimination of highwaymen and pirates transformed western Europe into one of the safest regions in history. In the 1480s, roughly one western European in a hundred was murdered, whereas by the 1780s that fate awaited only one in a thousand. Between 1807 and 1860, the Royal Navy seized sixteen hundred slave ships.

5. Storm of Steel and the Nuclear Age

Twentieth-century total wars destroyed European hegemony and global economic integration, but the invention of nuclear weapons and mutual assured destruction ultimately shifted superpower conflict to containment, proxy wars, and digital dominance.

Norman Angell served as the Paris editor for the bestselling British broadsheet The Daily Mail before publishing his famous book The Great Illusion in 1910. Angell predicted in 1910 that economic interdependence had made war obsolete, but his timing proved disastrously wrong as World War I erupted four years later. Fifteen million people were killed in World War I over four years, followed by twenty million people killed in civil wars following World War I. Fifty to a hundred million people were killed in World War II between 1939 and 1945.

Britain's success as a global policeman eventually undermined its own position as the spread of industrialization created rising new powers and unknown unknowns. The United States economy outgrew Britain's in 1872, followed by Germany's economy in 1901. Britain accounted for 9 percent of the world's total GDP in 1870, compared to 3 percent today. Britain also accounted for 23 percent of the world's manufacturing and trade in 1880, falling to 14 percent by 1913.

World War I bogged down into static trench warfare because military command and control systems failed to keep pace with modern firepower and defensive adaptations. At the Battle of the Somme in July 1916, 20,000 British soldiers were killed by lunchtime on the first day, with another 300,000 casualties following over the next four months. Britain, France, Russia, and the United States spent 36,485.48 dollars for every enemy soldier killed. Germany and its allies spent 11,344.77 dollars per enemy corpse.

Mutual Assured Destruction

The Wall Street crash of 1929 destroyed the remaining integration of the nineteenth-century world-system as nations retreated behind protectionist trade barriers. Four billion dollars of wealth evaporated on Wednesday, October 23, 1929, with nine billion dollars of American riches evaporating by Thursday lunchtime. The United States introduced twenty-one thousand tariffs to keep out imports, and by the end of 1932 international trade shrank to one-third of its 1929 level.

The invention of nuclear weapons created a condition of mutual assured destruction that prevented direct superpower war while shifting conflict to containment and proxy wars along the inner rim. During the Cuban Missile Crisis in 1962, the world faced a thirteen-day standoff when the Soviet Union deployed nuclear missiles to Cuba. The United States and the Soviet Union held seventy thousand nuclear warheads collectively at their peak in 1986. The two atomic bombs dropped on Hiroshima and Nagasaki killed 150,000 people.

The Singularity

China's staggering economic rise has created a powerful geopolitical rival for the American globocop, shifting the strategic balance in the western Pacific. In 2011, Australia faced acute diplomatic dilemmas trying to balance its primary economic partner, China, which fueled its mining boom, with its primary security partner, the United States. By 2006, China accounted for 15.4 percent of world economic output, while the American share stood at 19.5 percent. The American defense budget reached $690 billion in 2012, while $5 trillion in goods passed annually through the South China Sea.

The computerization of warfare and the introduction of remotely piloted aircraft are transforming combat, drastically reducing human casualties in targeted operations. The U.S. MQ-9 Reaper drone and MQ-1 Predator systems log millions of flight hours, loitering over targets to establish patterns of life and executing precision strikes with Hellfire missiles. Israel's Iron Dome system successfully shot down 90 percent of incoming rockets in November 2012. A top-of-the-line MQ-9 Reaper drone costs $26 million, whereas an F-35 fighter jet has an anticipated cost of $235 million.

Duke University neuroscientist Miguel Nicolelis demonstrated brain-to-brain interfacing by connecting the brain activity of rats in Brazil to rats in North Carolina over the Internet. The human brain weighs 2.7 pounds and generates 10,000 trillion electrical signals flashing every second. Futurists project 2045 as the date for the Singularity when supercomputers host all human minds. The technological Singularity and brain-to-brain interfacing threaten to merge human minds with machines, potentially rendering violence obsolete in an ultimate endgame of death.

10 Key Ideas

1. War is a horrific engine of destruction that has paradoxically served as the primary historical mechanism for forcing human cooperation and creating larger, safer societies.
2. Ancient empires suppressed local feuds and daily violence by establishing strong central authority, functioning as stationary bandits who protected prosperous subjects to maximize long-term tax extraction.
3. Population growth in agricultural landscapes caged human populations, making running away impossible after a defeat and forcing people into larger, more organized societies.
4. Military innovations such as fortifications and weapons triggered a Red Queen Effect, where societies had to continually run faster in organization and technology just to stay in the same place.
5. Even successful wars of conquest eventually reach a culminating point where rising costs outweigh the gold and glory gained from expansion.
6. Spaniards introduced muskets capable of piercing plate armor at a hundred paces in the 1520s, breaking the cycle of feudal anarchy.
7. The open-access economic order relies on the cooperation of an invisible hand of market forces and an invisible fist of state-backed violence to provide security and enforce rules.
8. World War I bogged down into static trench warfare because military command and control systems failed to keep pace with modern firepower and defensive adaptations.
9. The invention of nuclear weapons created a condition of mutual assured destruction that prevented direct superpower war while shifting conflict to containment and proxy wars along the inner rim.
10. The technological Singularity and brain-to-brain interfacing threaten to merge human minds with machines, potentially rendering violence obsolete in an ultimate endgame of death.