I know the Great Wall was useful to defend against enemies on land, but is there any record that people ever tried to beat the Great Wall by digging tunnels under it? If not, why didn't it happen?

  • 3
    I don't think the idea was to have some kind of Trumpian barrier to any and all transit. Rather it would be useful to impose a barrier to an entire army, much like a river would. The invading army could of course find a way through, but they can't just march right through in good order, and that would make them vulnerable during the crossing.
    – T.E.D.
    Commented Oct 27, 2016 at 13:22
  • Walls also help against raiders, as they slow them down when entering, but more importantly, when trying to leave overloaded with booty.
    – user15620
    Commented Mar 7, 2020 at 17:15

2 Answers 2


Most of the Great Wall was never assaulted and was more symbolic than anything. Most of the rest only ever had to deal with small groups of roving/semi-nomadic brigands, not organised armies.
And to tunnel under something like the Great Wall in such a way as to not draw attention to your efforts you'd need a pretty large group of tunnelers, and start at a considerable distance from the wall.
Another factor to consider is that a lot of the wall (and all the pieces that were actually potential targets for larger invading groups) were/are situated in mountainous areas. You'd have to tunnel through solid rock, not soil. While easier to hold a tunnel, it also is very hard labour, especially without heavy machinery. You'd end up with a tunnel that'd not be capable of infiltrating a sizeable force quickly, meaning you'd have to make it even longer to end up in an area where the defenders are unlikely to see you emerging and setting up camp for days or weeks in order to get all your forces through the tunnel before starting the assault.

For the problems faced with tunneling assault tunnels that have to remain undetected for extended periods, look at North Korea's tunnels across the DMZ, Hamas's into Egypt and Israel, and the Mexican drug cartels' into the USA.
The DPRK uses heavy machinery to make tunnels large enough to drive tanks and trucks through, which means it takes years to complete each tunnel, and the South Koreans have got pretty good at finding and destroying them.
Hamas and the druggies make narrow, dank little tunnels that often you can't even walk through but have to crawl, and those too are often detected and destroyed quickly. They too have powertools, but no heavy construction equipment.

For a militarily viable tunnel you'd need the DPRK style, and without bulldozers, dump trucks, and pneumatic drills you'd need a lot more time to complete them. Not a viable solution. (Taking 10 years to build your tunnel? Easier to go raid another neighbour...)

  • History of "*The Great Escape" well describes the difficulties of constructing a tunnel surreptitiously. Note that all digging and construction for those three tunnels was performed by Canadians with mining experience in Northern Ontario, Quebec, and the north-West territory. Disposing of the excavated dirt, without raising suspicions, is one of the more notable hurdles. Commented Mar 6, 2020 at 20:12
  • @T.E.D. should probably come back and make his comment above into an answer that's better than this one. "It's too much work for not enough benefit" is the right answer but everything else about this is off: The GW wasn't symbolic for the Ming. If they left open areas, the Northern Yuan would've used them. Similarly, the steppe nomads had no other neighbors worth raiding compared to China and centuries to work with. It wasn't about it being impossible but utterly impractical compared to bribing or killing a garrison at one of the mountain pass gates.
    – lly
    Commented Mar 7, 2020 at 9:25
  • Similarly, disposing of the excavated dirt would've been a non-issue. The Chinese weren't monitoring piles of dirt in the Ordos Loop, let alone the mountains. They would've depended on spies or allies in the hordes to come tell them what was up. It's true that one factor would've been the dirth of trained miners on the Mongolian steppe. The nomads themselves probably would've had an issue with taking such a cowardly way in, instead of proving themselves in battle, depending on their leader.
    – lly
    Commented Mar 7, 2020 at 9:35

If you had been to the Great Wall, you would find walls were built on selected mountain ridges. Meanwhile these mountains are pretty rocky and steep. This is just a supplement of @jwenting's answer.

  • Sorry you're getting downvoted so much, but you should at least include some of the info from history.stackexchange.com/questions/32285/…, if not something off-site. And you'd probably still get downvoted, since being on top of the hill should make it easier to tunnel under the wall.
    – lly
    Commented Mar 7, 2020 at 15:13

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