Last week I posed the mystery of why the Great Wall of China was so small at the top of the hills but so large at the bottom. Anyone can jump right onto it at the top. Where Europeans built castles designed to keep even a single attacker out, something else was going on with this Wall. Lots of people took up the challenge to think of something and the answer you will see below has pretty much been given by several contributors.
Before giving you an answer, let me admit right here that it is actually hard to find out what the ‘official answer’ is. Mainly this is because the true deliberations are based on strategic assessments that, even in China, are not usually part of open debate: they are usually unrecorded. The interpretation of later historians is just an informed guess, often tainted by the wish to glorify this or that commander, or, if the interpretations come from memoirs or writings by the military commander itself, by political and self-esteem considerations. As Tolstoy (not Dostoyevsky as a reader helpfully reminded me of!) and Von Clausewitz pointed out, the reality of war and the real considerations are a million miles away from how most military writers depict them. So as far as I am concerned, there is no ‘official’ answer (apart from the obvious throw-away answers that this was how the architects designed it), merely answers with different levels of plausibility.
Mainly, the Wall seems designed to keep out horses, not people, and to itself serve as a road to move troops between different segments of the wall. The main purpose of fortifications half-way up hills was then to make it hard for a large group of foot soldiers to go over the wall and overtake the garrisons at the gate in order to open it up for horses. At the top of steep hills, where horses could not come anyway, all this Wall was for was to move foot soldiers and building material around, much like you use the previous bits of a railway track to build the next bit.
The deeper question is why it was sufficient to stop horses. Mainly it was a matter of mobilisation: the Chinese empire had many more people in it than the Mongols (easily a 100:1 advantage in terms of total population), but the overwhelming majority of the Chinese were farmers whilst the Mongols were with their horses all the time and could assemble in larger numbers unnoticed by the Chinese.
Was there no standing army large enough to repel invaders? Yes, there was a large standing army but it had many duties. The standing Chinese imperial army was now and then stretched to its limits in quelling uprisings or in battles with other imperial factions, so it often occurred that the centres of power (such as the forbidden city) had limited standing protection. And of course there was a lot of Wall to guard.
So yes, once alerted, the military might of the Empire was immense as tens of millions of farmers could be mobilised into troops (and Wall builders!) within a few weeks and months. So the Chinese did not have to fear a slow invasion by all the Mongols. Similarly, they did not need to fear Mongols on foot as they were much less of a threat than Mongols on horses, so it did not matter much if some Mongols would scale the hills and jumped over the short Wall there: without horses they could not quickly reach something critical, nor bring back their loot.
Yet, an invasion by a mobile cavelry like that of the Mongols could at times have decapitated the Chinese Empire before it had time to mobilise. And once you control a bureaucracy like the Chinese, you dont need to fear mobilisation and can enjoy the fat of the land. Just read what Kublai Khan (descendant of the most successful Mongol raid ever) was up to in China with all the pleasure houses he got them to build for him and you will realise what China had to offer the Mongols. What goes for massive invasions also goes for less ambitious raids, in which smaller bands of horse-riding Mongols would sweep in and steal something of value (women and luxury goods).
So the strategic situation for a long time was one whereby the Chinese had enough of a standing army to station large numbers of guards at the foots of the hills of this Great Wall, i.e. where there were gates, but not enough to continuously guard all parts of the Wall such that no-one on foot could come in or to repel a concentrated mass-attack. Yet, the Wall meant that even any large attack would be slowed down considerably. Even if a garrison would be overwhelmed, it could collapse part of the Wall to make the gates useless or to prevent the Wall itself from being used as a road. Given that respite, the Mongols would face overwhelming numbers once they finally managed to come in with their horses.
So the answer involves a bit of military strategy, a bit of economics (pastoralist Mongols versus peasant Chinese), and a bit of technology.
Champagne to the many who clearly said the same thing last week. Diet water for the rest.
Even accepting your thesis for the Ming, because that was the only time that the Chinese actually attempted to build a single unified wall covering the whole of their northern frontier, the Ming wall was:
1. never completed
2. ineffective against repeated Mongol incursions, most spectacularly Altan Khan’s raid on Beijing itself in 1570
3. ineffective against the ultimate Manchu conquest in 1644 or the decades of Manchu raids across the wall that preceded it
The Ming wall was a mark of military and fiscal weakness like their ban on foreign contact and their abandonment of naval construction. More successful dynasties did not want or need such a wall.
sure, I wont argue with any of that. I don’t see why you need a continuous wall though to protect against raids or even larger invasions. Dozens of smaller bits will serve pretty much the same function. It all depends on the size of the enemy, entry points, etc.
As to whether the Wall was successful or not, that is a whole different question. I am sure there will be historians who claim versions of the wall were successful for some time, but I leave it to them to take up the challenge.
The trouble with the Wall myth is that it anchors so many smaller myths about Chinese history. Your description of how the Chinese empire responded to nomad incursions and invasions is pretty much the standard historiography but it suffers the distinct weakness of never actually happening in the real world.
The Yüan and Qing dynasties, for example, suggest that the best strategy for dealing with the northern frontier is a dynasty of nomad origin. When you consider that bother that the ruling families of both the Sui and Tang were of mixed Turkic and Chinese origin you are starting to get something fairly persuasive. Considering the number of nomadic dynasties that controlled at least northern China the Han collapse to the Sui foundation, and again between the Tang collapse and the Mongol conquest, you are getting a very large block of time when the Chinese ignored static defences and relied on expeditionary forces operating far beyond the line of the Ming or any other wall. Attempts in the first half of the Ming dynasty to mount long distance expeditions were spectacular failures, culminating in the actual capture of the Zhengtong Emperor in 1449.
Horses do not grow in China. Horses grow in the grasslands to China’s north in vast numbers. An expeditionary defence requires lots of horses. Dynasties that operated a network of allies and clients in nomad territory had access to horses. The Ming, cowering behind their incomplete wall, did not.
The Chinese empire generally dealt with its nomad problem in more or less exactly the same way as its Roman, Iranian and Indian counterparts.
Focussing on a mythical and unique China immured eternally and effectively is charming, but it’s not history.
“Focussing on a mythical and unique China immured eternally and effectively is charming, but it’s not history.”
Indeed, and neither is it what I say in my posts :-)
I was talking about why the wall is so short on top which lead to a discussion of the strategic considerations that are likely to have pressed on the minds of the builders. The topic of whether it worked and what else happened in Chinese history is an entirely different discussion.
Wasn’t that Tolstoy (and Clausewitz)?
yes yes, you are right. Will update the text. Thanks. I did actually read both books but I am bad with names.
My understanding is that it was designed to contain invaders and cut them off from their supply lines, rather than stop them invading per se…?
Sorry, I think the question might be being fudged here. It seems to have slipped into “why the wall at all” rather than “why is the wall high on the flat, and low on the ridges”
Arguments about fixed defences vs. fluid operations are one thing, but the original question was about the height of those fixed defences, not why (or whether) they were a good idea or not.
It seems reasonable to say that in the fertile valleys , the most valuable country and also where the roads needed for baggage trains where, the wall needed to be a real barrier requiring siege techniques . On the other hand when the wall was on high and difficult to traverse ground, the wall simply needed to be an delaying obstacle-‘trip wire’.
Never overlook incompetence an inexperience I say.
Prior to the building of the Great Wall no one had much idea about the military implications of such a wall, nor any expertise in building a structure that long.
A lot of the purpose of the wall was political, not military. It dealt with surplus population (who could otherwise be rioting), it demonstrated the superiority of the Chinese over their neighbors and it provided some level of security to locals, who were not trained to understand the strategic advantages & disadvantages of fixed fortification against mobile enemies.
The best reason for building the wall was not because the vast Chinese nation feared the neighbouring warring tribes (they spent a lot of money on keeping them divided), but because they could.
Militarily there was some value in reducing nuisance raiding parties and directing large mobile forces to key points in Chinese defenses, but these were secondary and testing by wargaming only as, again, there were no practical examples to draw on for how a ruddy long wall would help secure an empire.