War: What is it good for? (27 page)

So why did New and Old World military methods follow such different paths? Frankly, we don't really know, because historians have spent remarkably little time asking such big comparative questions. But in the current state of the debate, the most compelling explanation may be a deceptively simple idea offered by the biologist turned geographer Jared Diamond in his book
Guns, Germs, and Steel
.

The Americas, Diamond points out, basically run north–south across the globe, while Eurasia runs east–west (
Figure 3.12
). In Eurasia, people could move back and forth along the lucky latitudes, sharing ideas and
institutions, without having to leave this band of roughly similar ecological zones (what geographers call a biome). In much of the Americas, by contrast, people could not move very far to the east or the west within a biome; to fan out along the continent's long axis, they would have to go north or south, crossing daunting deserts and dense jungles.

This, Diamond suggests, would have had two consequences. First, because it was so much more difficult to move north–south across biomes than east–west along them, the communities of people able to share ideas and institutions would have been smaller in the New World than in the Old. If Eurasia had larger communities of metalworkers than the Americas, producing for markets that were larger too, we should perhaps not be surprised that Eurasians came up with useful ideas like bronze a lot faster than Americans. And second, Diamond suggests, when people did come up with useful ideas, they would be able to spread them farther and faster along the biomes in the Old World than across the biomes in the New.

This seems to fit the facts quite well. By the time Mesopotamians came up with bronze weapons in the fourth millennium
B.C.
, they already had contacts stretching as far as India and the Mediterranean, linking more people than any comparable network in America would do before the Inca Empire in the fifteenth century
A.D.
And once Mesopotamians had bronze weapons, the idea spread quickly along the lucky latitudes. Within fifteen
hundred years, people in what we now call China and Britain had bronze weapons too.

The jury is still out on why Native Americans didn't invent bronze weapons, but Diamond's thesis seems to be the best contender, and it explains the odd pattern of American archery even better. For reasons as yet unknown, prehistoric hunters had abandoned the bow as they moved northward across the biomes separating Africa from Siberia and then moved back southward through America. It took tens of thousands more years for the bow to spread all the way to the eastern end of Siberia. When bows did finally reach the Americas, being carried across the Bering Strait into Alaska around 2300
B.C.
, they took twice as long to pass through all the biomes separating Alaska from Mexico as Eurasian bronze weapons had needed to travel roughly the same distance within just a few biomes from Mesopotamia to England.

If Diamond is right that geography mattered more than culture in creating these differences, one further pattern should also be visible. We should find that while the pace of change was slower in America than Eurasia, its general direction—from farming to caging to productive war to Leviathan—was the same.

Broadly speaking, that is just what we do find. In the countries we now call Mexico and Peru, people domesticated what plants and animals were available by about 4500
B.C.
At first, change came almost as quickly as in the Old World. In the Middle East it took roughly four thousand years to get from the first farmers to the first Leviathans (at Uruk and Susa, around 3500
B.C.
); in the New World, it took roughly four and a half thousand to get to Teotihuacán and the Moche culture, around 100
B.C.

The Eastern and Western Hemispheres both went through similar two-steps-forward-for-one-step-back processes, producing strings of revolutions in military affairs. In Mesoamerica, Teotihuacán apparently introduced the first regular, disciplined formations, as well as hugely increasing the size of armies. By
A.D.
150, little bands without helmets, shields, or armor gave way to forces perhaps ten thousand strong. Some men, at least, started wearing quilted cotton helmets, which, although they may not sound very safe, could apparently be quite effective against stone axes.

By
A.D.
450, armies were probably twice as big, with elite troops wearing quilted cotton armor as well as helmets. Compared with the revolutions in military affairs in first-millennium-
B.C.
Eurasia, the American improvements were unimpressive, but Teotihuacán was nonetheless treading the
same path as the Old World Leviathans. And, just like the Eurasian empires, Teotihuacán eventually fell, with its urban core sacked and burned around
A.D.
650, probably by invaders from western Mexico. In further parallels with the Eastern Hemisphere, Mesoamerican military organization then collapsed. Post-Teotihuacán wall paintings show no armor at all, and a proliferation of hilltop forts suggests that law and order broke down.

Mesoamerican war turned productive again in the tenth century. A group called the Toltecs carved out a large kingdom, ruled from the city of Tollán (also known as Tula). Toltec fighters wore more cotton armor than Teotihuacános and introduced a new weapon that archaeologists call the curved club, made of oak studded with flakes of obsidian. The Toltec Empire probably never matched the scale of Teotihuacán's and certainly did not last as long. In the twelfth century, migrants from farther north overwhelmed it, burning Tollán around
A.D.
1179. (Some of these invaders, the Chichimecs, might have brought the bow and arrow to Mexico at this time.) Mesoamerica then fell back into constant wars between small city-states until the fifteenth century, when another group of northern newcomers—the Aztecs—renewed productive war.

We know more about the Aztecs than any earlier American society. Their success depended as much on diplomacy and clever marriages as on fighting, but when they did fight, they did it better than Teotihuacános or Toltecs. Aztec armies marched in multiple divisions, each about eight thousand strong, capable—like the corps in Napoleon's armies—of advancing and fighting on separate lines and then concentrating quickly. Logistics improved even more, with defeated enemies now being required to provide supplies. A professional officer corps took shape, and even ordinary soldiers got basic training.

Battles began with slingshots and archery from the wings before shock troops closed for hand-to-hand combat, protected by thick cotton armor, large shields, and wooden helmets covered in feathers. The shock troops attacked in loose formations so they could swing “broadswords,” four-foot-long oak sticks studded with rows of obsidian teeth, and advanced in two ranks, the first of elite aristocratic fighters and the second of veteran commoners. Commanders rotated the two groups in and out of combat to avoid exhaustion and tried to keep a big reserve, to be committed at the decisive moment to extend the line and outflank the enemy.

Aztec armies built the biggest empire Mesoamerica had seen. Its population boomed, to perhaps 4 million, with 200,000 in the capital city, Tenochtitlán.
Agriculture reached new heights, trade networks stretched farther than ever before, and households prospered. We have no way of knowing how safe Aztecs were, but surviving scraps of poetry suggest that they certainly
felt
safe. “Proud of itself is the city of Mexico-Tenochtitlán,” went one song. “Here no one fears to die in war. This is our glory!”

In the Old World, emigration, assimilation, and independent invention spread farming and caging beyond their original homelands in the lucky latitudes. If Diamond's theory is correct, we should expect the same thing to have happened in the New, only more slowly, because of the challenges of crossing biomes, and once again this seems to be what the evidence shows. To take just one example, not until
A.D.
500 did corn, squash, and beans make their way from Mexico northward to the river valleys that cut across the scorched deserts of the American Southwest. The region was wetter in those days, but even so, rainfall was unreliable, and the only way to farm the parched land was by digging irrigation canals. Nothing cages people quite like lack of water, and by
A.D.
700 hundreds were congregating in the best locations and fighting fiercely as population grew. Eighth- and ninth-century sites are full of skulls shattered by stone axes, arrowheads lodged in ribs, and villages burned to the ground.

After 900, though, the fighting apparently stopped. Archaeologists often call this the Chaco Phenomenon, after the impressive sites in Chaco Canyon, New Mexico, but Pax Chacoa might be a better label. People concentrated in even larger clusters (perhaps ten thousand in Chaco Canyon), built bigger houses with more storerooms, and traded farther afield.

The Pax Chacoa lasted until about 1150, and then it too ended. Driven perhaps by a worsening climate, people abandoned big communities such as Chaco Canyon and Snaketown on the Gila River in Arizona. They fought more, failed to maintain their irrigation ditches, and gave up long trading trips. And on the process went. Even more impressive towns grew up on the Gila in the thirteenth century, often decked out with ceremonial ball courts strikingly like examples in Mesoamerica, but the Hohokam culture (as these sites are called) fell apart too by 1450.

We could pile up more examples, such as the extraordinary Native American city at Cahokia on the Mississippi, but these few, I hope, are enough to make the point. Differences in geography shaped how the process worked in each specific place, but everywhere in the world that farming could get a toehold, the cage closed rapidly between
A.D.
200 and 1400, creating productive war.

The one big exception to this pattern was, as we have seen, the Eurasian
lucky latitudes. Here geography changed its meanings in the early first millennium
A.D.
as the agrarian empires became entangled with steppe nomads, trapping the now not-so-lucky latitudes in a cycle of productive and counterproductive wars.

Between
A.D.
200 and 1400, Eurasia's formula of horses plus steppes plus agrarian empires was unique. Possibly, given time, the formula and the disastrous cycle it yielded would have been replicated elsewhere. In the eighteenth century, when European horses arrived on the steppe-like Great Plains in North America, the Comanche Indians carved out a nomad empire that—despite all the cultural differences between Native Americans and Mongols—historians regularly liken to a smaller version of Genghis Khan's. Eventually, perhaps, similar nomad empires might have arisen on the steppes of Argentina and South Africa.

But as it was, Eurasia paid a high price for being trapped in this cycle between
A.D.
200 and 1400 while so much of the world was experiencing productive war. The enormous lead in development that Eurasians had built up over the previous ten thousand years was steadily whittled away. The gap between, say, Ming China and the Incas in the fifteenth century remained huge, but if the trends of 200–1400 had gone on long enough, that would have changed. Other things being equal, the twenty-first-century world might have been one in which the heirs of Great Zimbabwe had unified much of sub-Saharan Africa and were fighting fierce cavalry battles in the Nile Valley as they pushed their way toward the Mediterranean. Or one where iron-armed Mexican armies were bringing the last free farmers of North America under control and building fleets to battle the famous sailors of the Polynesian Empire. And one in which empires kept rising and falling along Eurasia's lucky latitudes without ever getting the upper hand over the steppe nomads.

Given another half-dozen centuries, the rest of the world might have caught up with Eurasia. But Eurasia did not give the rest of the world another half-dozen centuries.

The Happy Few

In 1415, a handful of Europeans put the world on notice that the clock was running out.

That October, a cold, miserable English army huddled between two damp forests near Agincourt in northern France. For two weeks it had
been dragging its wagons through the mud, trying to escape a French host that outnumbered it four to one. But now it was trapped.

As was the custom, the English king stepped forward to cheer his men up before the slaughter. “This day is called the feast of Crispian,” Shakespeare imagined him telling them. On this day, said Henry V, they would win one of the great victories of all time, so great, indeed, that

He that shall live this day, and see old age,

Will yearly on the vigil feast his neighbours,

And say, “To-morrow is Saint Crispian”;

Then will he strip his sleeve and show his scars,

And say, “These wounds I had on Crispin's day
”

…

This story shall the good man teach his son;

And Crispin Crispian shall ne'er go by,

From this day to the ending of the world,

But we in it shall be rememberèd;

We few, we happy few, we band of brothers
.