Currently, I am running a d&d campaign based of of 11th century middle ages, with the world including multiple kingdoms with cultures and technology based on that time period.

Given this context. My question is if there would be a sort of alternative to cannons that could be placed on a ship from that period. However as stated in the title, it can't involve the use of gunpowder or magic. Because you see in the setting magic users are not exactly common (as they are being hunted down and killed by the government)the use of magic is not entirely unheard of.

So , is there a plausible way to accomplish such a thing?

Any and all feedback is much appreciated. :)

  • $\begingroup$ why can't you use gunpowder? $\endgroup$ Oct 25, 2017 at 21:58
  • $\begingroup$ Because saltpeter hasn't been discovered yet-and it's one of the main ingredients of gunpowder. $\endgroup$ Oct 25, 2017 at 22:03
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    $\begingroup$ so whats wrong with sticking to the classical trebuchets catapults and ballistas? $\endgroup$
    – anon
    Oct 25, 2017 at 22:04
  • $\begingroup$ @anon - Nothing particular, I'm just curious to see if there is something that works similarly. As stated in my comment on A.C.A.C. answer. $\endgroup$ Oct 25, 2017 at 22:11
  • $\begingroup$ @Mevior Alstrad - saltpeper was known since ancient times (Chinese mined it since at least mid-1st century AD), what wasn't known are effective refining methods. But it's still debatable whether refined saltpeper led to the discovery of gunpowder, or methods came in answer to increased demand. $\endgroup$
    – Alexander
    Oct 25, 2017 at 22:44

5 Answers 5


Steam cannons to the rescue

Steam technology has been found since before Christ. Medieval smiths could make boilers and a release valve attached to a cannon.


  • get a thick metal chamber with only 1 hole
  • attach a quick release valve to end of a the hole
  • attach a cannon grade pipe to the release valve
  • boil water till the chamber reaches max pressure
  • put a cannon ball in the pipe
  • quickly flip the valve to release all the pressure into the pipe driving the ball forward just like gunpowder


  • $\begingroup$ Hmm... interesting. Could you possibly elaborate on that though? I'm not quite sure I understand how it works. $\endgroup$ Oct 25, 2017 at 22:05
  • $\begingroup$ I suspect the high pressure valve might be difficult to manufacture in that time period but the steam idea is good $\endgroup$
    – Slarty
    Oct 25, 2017 at 22:52
  • $\begingroup$ @Slarty I agree its not likely, but it isn't impossible either. $\endgroup$
    – anon
    Oct 25, 2017 at 23:23
  • $\begingroup$ This solution would be workable, but not terribly practical I think as the time needed to build up steam would be quite lengthy $\endgroup$
    – Rissiepit
    Oct 26, 2017 at 1:29
  • $\begingroup$ You need to heat the cannon for minutes to shoot just one, not very heavy projectile, not too far, without almost no destructive or penetrating power, then proceed to reload it during at best half an hour. Completely useless - that's why in the real world no one has ever tried to make them work. $\endgroup$
    – Rekesoft
    Oct 26, 2017 at 9:38

There are various forms of catapult. https://en.wikipedia.org/wiki/Catapult Trebuchet's were gravity powered, and I think would be erratic used on a soft platform like a ship, but torsion catapults should work.

The traditional catapult threw stones. No reason you couldn't do the equivalent of chain shot to take out the other ships rigging, or case shot as an anti-personnel weapon.

How about a ballista? This is essentially a crossbow on steroids. https://en.wikipedia.org/wiki/Ballista

Here's another idea: https://en.wikipedia.org/wiki/Sauterelle The sauterslle was a crossbow like device used to launch bombs. Even if they don't have explosives, it could hurl the equivalent of Molotov cocktails.

While dangerous as hell to the user, you could implement some form of flame thrower. There was an ancient technology show where they tried to make such a weapon. The range was pathetic, and I think they ended up burning their own ship down, but when you have to invent a new weapon system to meet a TV schedule Mistakes Will Be Made (tm)


Most answers here adequately address using potential energy to generate the force in ballistics such as catapults, or chemical energy from alchemic reactions.

Here's something bordering reasonable doubt:

If there was a need to have a range superiority over the "current warfare meta-tech" of catapults/alt-cannons, A modified-optimised version of Archimede's Death Ray could be used on one large ship or a well co-ordinated array of smaller vessels (opening up to interesting avenues of "burn-squad" crews or smaller team elements).

Obvious time of day constraints aside, it would vastly overpower (and possibly catch by surprise) day-time ballistic warfare.

  • $\begingroup$ This answer deserves a bounty. $\endgroup$ Jan 3, 2018 at 20:21

Use traditional siege weapons like ballistas or catapults.

  • $\begingroup$ Damn, I misread, I thought you had to make a cannon work without gunpowder. $\endgroup$
    – anon
    Oct 25, 2017 at 22:01
  • $\begingroup$ @A.C.A.C. - True, but when I say cannon alternative, I kind of meant something that works in a similar way to a cannon. So sorry should have made that more clear. However you did remind me that catapults were mounted on boats, so thank you. :) $\endgroup$ Oct 25, 2017 at 22:08
  • $\begingroup$ Tebuchets, ballistas, catapults, and the like seem a robust, cheap alternative. Cost of the weapon is a very important factor in it's acceptance and use. So is the survivability of the weapon - it must reach the battlefield intact after a slow, bumpy, arduous, weatherbeaten trip. $\endgroup$
    – user535733
    Oct 26, 2017 at 1:16
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    $\begingroup$ @MeviorAlstrad what do you mean by "a similar way to a cannon"? Do you mean it must be explosive? Or it must be ballistic? Or it must be used to break up infantry formations? Confusing. $\endgroup$
    – user535733
    Oct 26, 2017 at 1:19

I love knowing that cannons have been around since, yea, early medieval times. After all gunpowder itself is an ancient invention. King Henry 8th was supposedly the first to put cannons on navy ships, back when ships still had 'sterncastles.' In Sir Eveland's Medieverse there're cannons right alongside chivalric cavalry--honor vs. no honor--and no magic is needed at all because, frankly, that concept is very realistic. Consider maybe a new form of gunpowder that doesn't require saltpeter, a magical powder which can be used in not only cannons but petards and explosive quarrel-heads as well. If you don't believe that cannons existed in the 11th century than google 'crakys of war' (Scottish) or pots-de-fer (French).

  • $\begingroup$ This question asks about alternatives to cannons, not cannons themselves. This doesn't answer the question. $\endgroup$
    – kingledion
    Jan 3, 2018 at 21:48
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    $\begingroup$ :-) Fantasy Fan 3.0, this was a great first answer. My collegues are correct, it doesn't answer the question, but is more suited as a comment to help the OP (original poster) to improve his question. nevertheless, your insight and effort to help bring greater understanding to the issue is admirable. I look forward to your further participation on the site. Welcome! $\endgroup$
    – JBH
    Jan 4, 2018 at 4:53

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