This is the same material used in luxury watches to prevent scratches, it is called sapphire glass and now I am planning to donate 1000 units of these scratch-resistant glass cannons to assist the Yuan army in the late 13th century AD against the Mongol invaders. Is my strategy going to completely terrorize the Mongolian or expedite the founding of Ming dynasty?

  • $\begingroup$ Suggest you Google "How brittle is sapphire glass", assuming the real question is whether a cannon made of it will blow up on first use. $\endgroup$ Commented Jan 7, 2022 at 2:30
  • $\begingroup$ "Glass cannon" was intended to be an allegory, not an instruction. $\endgroup$ Commented Jan 7, 2022 at 9:52
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    $\begingroup$ @user6700 The Yuan Dynasty WAS the Mongol invaders of China in th elate 13th century, fighting the native Southern Song Dynasty. en.wikipedia.org/wiki/Yuan_dynasty $\endgroup$ Commented Jan 7, 2022 at 17:43

2 Answers 2


A Dead Army Yuan Army Full Of Glass Splinters

Materials that are hard are not necessarily particularly strong when it comes to surviving explosions.

The fracture toughness of sapphire glass is 2.0 MPa1, approximately the same as PVC. While PVC makes for great potato cannons, I highly recommend against attempting to use it as a rifle barrel.

Your cannons will explode spectacularly, and cause some truly horrific injuries to the gunner and anyone within five hundred feet in every direction.

  1. https://www.guildoptics.com/sapphire-properties/sapphire-properties/
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    $\begingroup$ Given the OP and any future reader might not already be familiar why hard but brittle materials are never a good idea in weaponry, you should specify that it is your OWN army that's dead, not the enemy. $\endgroup$
    – user93359
    Commented Jan 7, 2022 at 3:01
  • $\begingroup$ Good point, have clarified. $\endgroup$
    – Daniel B
    Commented Jan 7, 2022 at 16:48

Cannon were not so useful in China as they were in Europe. This is not because of any destructibility of the cannons, but because China made fortifications of earthworks, and Europe of stone. Europe's could be much higher (better against attack by ladder), but advent of cannon meant they switched over to earthworks and started heavily manning them to make up for the lower walls, because cannon are nowhere near as dangerous to earthworks.

Notice that earthworks (including sandbags) are still used as defenses, including against artillery. And this is with the development of explosive shells. Your Chinese forces will have cannonballs. (It would be hard for them to develop shells. Putting explosives in the shell is easy. Adding a fuse is also easy. Getting the explosives to explode when they will harm the enemy, not so easy.)

And that's even if the cannon are great.

  • $\begingroup$ Sounds like someone's been reading some Bret Devereaux. It is always nice to share your sources, especially one so useful and easily consumed. $\endgroup$ Commented Jan 7, 2022 at 9:54
  • $\begingroup$ Funny, you didn't chastise the other guy. Any particular reason for such a nasty double standard $\endgroup$
    – Mary
    Commented Jan 7, 2022 at 14:47
  • $\begingroup$ The other answer quotes a few random facts which are widely available, whereas yours is a summary of someone else's piece of work. Whilst I've no particular interest in being the copyright or plagiarism police, it doesn't seem that unreasonable to reference the source material you're sampling from, so that everyone else can benefit from it in its entirety and references it cites itself. Is that so unreasonable? $\endgroup$ Commented Jan 7, 2022 at 15:46
  • $\begingroup$ Changing your standards on the fly worsens your case $\endgroup$
    – Mary
    Commented Jan 7, 2022 at 22:04
  • $\begingroup$ I’ve added a citation to my answer for balance. $\endgroup$
    – Daniel B
    Commented Jan 8, 2022 at 2:43

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