D&D 5E Why do cities in Faerun have fortified walls?

[amethal]

City walls can also help when the local peasants get thoroughly fed up with being taxed and decide to do something about it.

Also there are usually cavalry barracks close to the city centre, which would seem a strange place to have them unless you think you might need to use them against your own subjects ...

 

[S'mon]

Walls save spell slots from casters so they can be used to battle siege casters.

A fireball-casting wizard behind arrow slits is a lot more potent than a fireball-casting wizard out in the open, yup.

 

[doctorbadwolf]

because no one has in the 50 years of D&D has made a campaign world with first thought to be how the world would evolve with magic...

Well that’s just plainly false

 

[squibbles]

I’d be more inclined to blame Howard for that. [...]

That's an interesting observation. Howard did create a thousands of years deep backstory with the the migrations of his different faux-invented ethnicities. But he also published all his work as short adventure stories in pulp magazines. Hyboria had to be retroactively reconstructed by L. Sprague de Camp, Lin Carter, and friends and is sketchy to the degree that there's no authoritative map of it--since Howard didn't make one, and since the distances in his stories aren't always consistent.

And yet, Gygax probably got his Conan stories from the fan-fic bloated, appendix-having, quotidian nerdlove minded collections de Camp edited--and definitely would have claimed that he was influenced by them more so than LotR (for possibly disingenuous legal reasons).

A fireball-casting wizard behind arrow slits is a lot more potent than a fireball-casting wizard out in the open, yup.

This kindof gives lie to the whole medieval paradigm of warfare D&D assumes. Fireballs are just stupidly deadly in an NPC mooks storm the walls scenario. But I guess there are a lot of assumptions to sort out. Do the defender and attacker have enough wizards on hand to keep up a steady stream of fireballs? If they do, then we'd start to see the adoption of something like the modern military system which, in response to overwhelming firepower, abandons fortifications in preference for mobility, concealment, and infiltration.

 

[S'mon]

This kindof gives lie to the whole medieval paradigm of warfare D&D assumes. Fireballs are just stupidly deadly in an NPC mooks storm the walls scenario. But I guess there are a lot of assumptions to sort out. Do the defender and attacker have enough wizards on hand to keep up a steady stream of fireballs? If they do, then we'd start to see the adoption of something like the modern military system which, in response to overwhelming firepower, abandons fortifications in preference for mobility, concealment, and infiltration.

Yup - really even the occasional Fireball would force dispersion on the battlefield. Close order infantry doesn't work when 20 of them are accurately incinerated with one spell - that's a lot more deadly than 19th century artillery, more like modern Hellfire missiles. It's a bit ironic as the Fireball & Lightning Bolt were originally magical versions of the Chainmail rules for Catapult & Ballista.
I don't think Fireballs are as good vs fortifications though, they kill soldiers in the open but lack explosive force. Arrow slits with compartmentalised defences are good vs fireballs and most other D&D AoE attacks. IME castle type fortifications remain useful on the D&D battlefield. Arrow slits certainly stay useful. Open topped walls & tower tops don't work well when the enemy has fireball & fly, though. In a high magic setting they should always be enclosed and compartmentalised.

From here:

 

[squibbles]

Yup - really even the occasional Fireball would force dispersion on the battlefield. Close order infantry doesn't work when 20 of them are accurately incinerated with one spell - that's a lot more deadly than 19th century artillery, more like modern Hellfire missiles. It's a bit ironic as the Fireball & Lightning Bolt were originally magical versions of the Chainmail rules for Catapult & Ballista.
I don't think Fireballs are as good vs fortifications though, they kill soldiers in the open but lack explosive force. Arrow slits with compartmentalised defences are good vs fireballs and most other D&D AoE attacks. IME castle type fortifications remain useful on the D&D battlefield. Arrow slits certainly stay useful. Open topped walls & tower tops don't work well when the enemy has fireball & fly, though. In a high magic setting they should always be enclosed and compartmentalised.

From here:

Good points.

The last bit about compartmentalized defenses and covered walls dovetails with the 1800s development of casemates, which were adopted to prevent mortars with shrapnel shells from hitting defenders from above.

...though I would not want to be on the wall in the top picture if its wooden hoardings were shot with a fireball.

A functional D&D response to flying enemies would probably look a bit different from either system since the defenders would need to return fire at whomever is above them, and neither hoardings nor casemates would work very well at that.

I stick to my assertion in post #40--also made by the OP--that the most secure D&D city is one that's built entirely underground.

 

[Rune]

I stick to my assertion in post #40--also made by the OP--that the most secure D&D city is one that's built entirely underground.

Until the umber hulks show up.

 

[Ixal]

I stick to my assertion in post #40--also made by the OP--that the most secure D&D city is one that's built entirely underground.

They are also really easy to besiege. Just bury the entrence and wait.
There are also other problems like lack of sunlight, ventilation, etc.

 

[S'mon]

They are also really easy to besiege. Just bury the entrence and wait.
There are also other problems like lack of sunlight, ventilation, etc.

Yes, I was just reading about the fall of Eben Emael this morning. An underground fortification is really easy to seal off. Castles are good because they control territory. An underground castle is just a bunker.

 

[squibbles]

Until the umber hulks show up.

That's true. But it's an issue for a castle too, since they can burrow up from below. Going under walls via sapping is one of the standard tactics in a besieger's playbook.

They are also really easy to besiege. Just bury the entrence and wait.
There are also other problems like lack of sunlight, ventilation, etc.

It's only easy if there is just one entrance or if the besieger knows the location of every secondary entrance--and the defender would make every effort to hide these. It could also be pretty difficult to surround a city with entrances on two sides of a major terrain feature, i.e. the stereotypical dwarf city under a mountain. If the defenders sallied on one side to attack the besiegers, the besiegers on the other side wouldn't be able to help (except in small numbers via teleportation).

You're right that ventilation and light are issues (though light could pretty straightforwardly be resolved via continual flame) but if the defenders were able to solve them--and they would have to to have built an underground city in the first place--then the waiting game isn't much different from a conventional siege. The besiegers can only win it if they possess better supply than the defender, and if the defender can't expect to be relieved by allies.

It's also not that easy to bury an entrance which looks like this:

Yes, I was just reading about the fall of Eben Emael this morning. An underground fortification is really easy to seal off. Castles are good because they control territory. An underground castle is just a bunker.

Bunkers can also control territory. If Eben-Emael didn't control territory, the Nazi's wouldn't have attacked it.

The way that a castle controls territory is by being the administrative center of that territory and by being an annoying threat to anyone living or operating nearby who doesn't control it. A castle doesn't fundamentally protect territory, even a village that is right next to it, except by sheltering the inhabitants. But if there are five guys with horses chilling in a hostile castle, you can expect to be attacked by them any time you don't have enough guys with you to scare them away. And if you are leading an army, it's a logistical nightmare to have hostile soldiers sitting in your rear area interfering with your supply lines.

A bunker can do the same thing (especially with a little help from magical surveillance, an owl familiar say).

--

I guess I don't really have an answer to ventilation issues. I don't have a sense of the engineering issues involved and am basically assuming them away in the same manner that giant megadungeons like undermountain and dwarf cities like moria assume them away. The whole enterprise of underground city building is basically sunk without proper ventilation... so that's a fair criticism.