What sort of defences would a fantasy city have?

[soldersbushwack]

These defences should be as low-tech and as simple as possible. So, I'll start with a few:

Simple defences: stone city walls, ditches, mazes.

Simple traps: spike pits, rope trips, garrotte wires, snares.

Simple non-magical fantasy defences: bundles of garlic, maybe even fields of garlic, lots of windows, holes and above ground areas for letting natural light through, moats with running water, lots of religious symbols, gargoyle statues, silvered traps, fire walls and pits to harm incorporeal undead slipping through walls. High towers and grid-like city streets to deliberately kick up wind to complicate flying. Areas with a heavy amount of undead and corpses to align the area into the negative energy plane and make healing and turning undead more difficult. Really tricky steps that are hard to walk over (especially for clumsy undead.)

More complicated non-magical fantasy defences:

Layered natural and unnatural areas. Magic-users can cast spells to animated and control the natural environment. Invaders should be on dirty ground with plants so that they can be entangled and attacked by animated trees. Defenders should be on paved streets.

Corpses should be burnt and mortuaries should be strictly regulated by the city to spread them out, prevent disease, build ups of negative energy and undead.

Traps to flash flood areas with water.

In Lovecraftian fantasy often stuff isn't magical but the knowledge of it still drives you insane. There could be memetic traps or cognitohazards hidden around the city. I'd guess this would overlap with the religious symbols and imagery above somewhat. These traps could be arranged so that they would only be visible while flying.

Simple magical defences: plenty of holy water, holy-water moats to prevent incorporeal undead, portals to the positive energy plane.

[LudicSavant]

Star forts (https://www.google.com/search?q=star+forts&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjL9du-277MAhWI4iYKHW3XDFUQ_AUIBygB&biw=1920&bih=920) are a historical adaptation to technologies that could easily breach castle walls (like various fantasy threats can).

[suburban]

Many of the defenses you've laid out are your typical historical 'medieval castle defense systems' - which makes perfect sense for a fantasy setting. But one thing a fantasy setting has that the real world didn't have to consider in the n-teenth century was attacks from the air.

Since you can't realistically put a roof over your whole city (unless you do it using magic), you might consider building the city, or parts of it, either underground or into a hill/mountainside. A natural cave system that has been improved upon would make a good start.

[JoeJ]

Many of the defenses you've laid out are your typical historical 'medieval castle defense systems' - which makes perfect sense for a fantasy setting. But one thing a fantasy setting has that the real world didn't have to consider in the n-teenth century was attacks from the air.

Since you can't realistically put a roof over your whole city (unless you do it using magic), you might consider building the city, or parts of it, either underground or into a hill/mountainside. A natural cave system that has been improved upon would make a good start.

Another option is anti-air defense towers spread throughout the city with overlapping fields of fire. On top of each tower there would be some type of light artillery - ballistas, catapults, or cannons if the setting has gunpowder. They would be light because a high rate of fire is more important than high damage in this situation.

[MrZJunior]

Stretch chains across the river to slow or stop boats passing. Scuttle ships to create blocks in the channel.

Clear the forest away from the walls to create a clear field of fire.

Have all the buildings built with arcades fronting onto the street to disguise your troop movements and protect them from attacks from above.

Stretch wires between tall towers to discourage flyers from diving into the city.

[Wulfskadi]

Since you can't realistically put a roof over your whole city (unless you do it using magic), you might consider building the city, or parts of it, either underground or into a hill/mountainside. A natural cave system that has been improved upon would make a good start.

This is DnD


If its cool we can skew realism a bit. What if a giant roof already existed? possibly the remains of a giant sea creature or a gigantic sculpture built by ancients. Or maybe some lunatic just decided to build a roof over their city. Either way, a roofed city is not a bad idea, I've seen it done before.

[Wulfskadi]

Another option is anti-air defense towers spread throughout the city with overlapping fields of fire. On top of each tower there would be some type of light artillery - ballistas, catapults, or cannons if the setting has gunpowder. They would be light because a high rate of fire is more important than high damage in this situation.

You have to remmber that if you're directly above a city, firing catapults at flying enemies that a vast amount of your ammunition is going to hit the ground, and possibly the people on the ground. For this reason, pepper guns would probably be the optimal weapon. (Pepper guns fire a shell full of small grains that spread out to make a cloud before impact. Doesn't do much more than hurt like hell but it can cause a person focusing on flying to either fall or smash into a building while also causing minimum damage to the surroundings.

[JeenLeen]

Depending on the setting, geomantic defenses could be an option. A city could be built so that the roads, buildings, and walls form a geomantic spell or focus energy to create a ward.

In an Exalted game, I was discussing things with the GM and it just made sense that city walls (at least of wealthy and/or old cities) had wards to prevent incorporeal undead and spirits from passing through the walls. Otherwise, a given scenario really made no sense. (It was a pre-made module where undead were besieging a city. But a large number of the undead had the power to become incorporeal. They should've been able to just go into the city at night, materialize, and slaughter most everyone.)
Barring this, I definitely agree with superstitious wards, like garlic or prayer strips, arrayed. Whether or not they actually work, folk might think they work.

A lot of the defenses probably depend on how common magical or undead threats are. If flying threats are rare, many cities might not make the cost to prevent them, so a given region may or may not try to prevent that (e.g., one that fights orcs on wargs verses one fighting elves on griffons). Sure, your city may be razed every few hundred years from a flying threat, but it's just not worth the expense beyond minor, cheap additions.

I can definitely see different funeral rites. Honestly, it'd odd that traditional cemeteries exist in D&D instead of cremation, seeing how often undead are an issue and even small small ones are level 1 dungeons for PCs.

[Tvtyrant]

Spelljammer does a good job of this, like placing asteroids above a city to prevent ships from approaching or building domes covered in spikes over everything.

Permanent magical wards would probably be placed around the city as well. In D&D things like genius loci and the hallow line can make a city hard to take.

[nrg89]

I think it's appropriate to also briefly touch upon "the arms race"; what new machines of offense would fantasy armies engineer in order to combat the new types of defense?

In a world that tries to cover themselves from air strikes with underground cities you would provoke new forms of siege; open pit mining (described perfectly in this Stackexchange answer (http://worldbuilding.stackexchange.com/questions/14385/to-assault-a-dwarven-city)). Siege engineers would need to work out ways to move a lot of dirt quickly (the question in the link covers giants besieging a dwarf city, so the giants could simply carry it away or use giant sized wheel barrows), and if we use vanilla DnD, a druid with move earth would be very valuable.

Again, just something everyone should briefly touch because the enemy is always learning and if a type of defense has been around for centuries that's a very long time for engineers to adapt (and believe me, there's more than enough gold to incentivize multiple engineers to work and correspond with each other day and night to find a good solution).

I also feel like one of the first things a world builder needs before she can start listing defenses is a price table. Walls are fairly useless against paratroopers so what happens if air travel and slow fall are dirt cheap? What about teleportation?
Sure, you might not move entire armies through magical means, but what about nimble strike teams who take out the food and water? You're going to have a pretty rowdy army under your command once everyone's thirsty and starving. Or what if they kidnap the noblemen and keep them for ransom?

A good price table is, in my opinion, the one thing to keep powerful magic from turning the world into the Tippyverse. That's the main reason I've banned transportation magic in my setting.

[Wranglyph]

A lot of deaths in ancient warfare were actually caused by diseases; keeping a lot of people close together in rough conditions tends to make them sick. For a city to withstand a long siege, good hygienics, and consequently, things related to water management and waste disposal, could be the difference between standing or falling. On the flip side, a city with an exceptional health system could deliberately introduce a vile disease into the mix and hope they can take it better than the siegers. The attacking army might have the luxury of a supply route, but they too must remain in close quarters if they want the siege to be successful.

[Storm_Of_Snow]

If magic's prevalent, the capital city at least would have magical wards built into their walls, and important structures would be similarly treated - they might need to be activated (which means your alpha strike is to assassinate the court wizards), or they might be permanently on (the 3rd edition WFB Seige expansion actually had such wards in the rules for precisely this reason). Depending on the level of magic involved (and how much the ruler can spend), such wards may only stop physical attacks on the walls, or they may prevent movement across them (maybe limited to physical, possibly extending to ethereal/incorporeal), or possibly even dimensionally lock the city to prevent teleportation and planar travel, and the more things they stop, the more inconvenient they'd be to the normal life of the population of the city and the less likely they are to be always on.

For flyers, if they're perceived to be a threat, the larger cities would likely have their own (either their own or part of the countries organised military forces), and may also have defences, which could be things like ballistas and scorpions firing bolts, single medium sized stones, clusters of smaller stones or arrows, nets, and potentially things like barrage balloons, which may themselves have defensive weapons slung from gondolas, and nets and ropes strung between the tether cables to entangle flyers. And I guess it's possible to have someone casting spells like wall of stone in order to put a roof in place if you get the time.

There's also the possibility of tunnellers - which would mean careful siting of the city in the first place to make it as difficult as possible (if you can), placing materials and structures that are either incredibly difficult to mine through or are impassable, counter mining, having trained tunnel fighters and so on.

[DuctTapeKatar]

I think that maybe some natural defenses might be handy. Having the city built into a mountain or somewhat underground is a good example. Here's a few more.

A structure I thought of for a desert environment was a large pyramid, with a set of stairs leading to the entrance on the top of it, protected by a structure similar to the Greek Acropolis. This gives you an advantage unless an enemy has flying units. Then, going down some more stairs, you'd have an intricate layer of tunnels which go under the ground, so you will always have space for supplies during a siege, or a quick getaway if things get dicey.

Another defense I thought for a more arctic landscape was a magically-induced snow-storm swarming around the city, with traps within the areas which people were the most likely to stumble through. Plus, with all that cold, any army would have trouble trying to get through due to the temperatures (unless they are wearing specially enchanted armor).

Also, if we are in a jungle or forest setting, just look at the Ewok Village from Star Wars or the Elves from Lord of the Rings. These would also be quite useful in a swamp.

Also, placing your city in the mouth of a giant volcano might also be a thing, as long as the volcano doesn't erupt any time soon. Lava moats could be very useful.

Another alternative is to place your city on the back of some giant monsters or a really big machine. Nobody in their right mind would attack a thing that size (unless you have an even larger flying thing).

[Lycanthrope13]

Depending on the setting, geomantic defenses could be an option. A city could be built so that the roads, buildings, and walls form a geomantic spell or focus energy to create a ward.

Like how the railroads make a giant Devil's trap in season 1 of Supernatural? Love that idea.I always figured there had to be some sort of warding to prevent enemies using passwall to ruin your whole defensive plan.

On siege engines, I would say light ballistae probably dominate. I wouldn't be hurling boulders onto a battlefield when there are giants that could throw them back. Probably some sort of fragile spear that fragments on impact, leaving the head lodged in the target with no shaft to grasp and pull it out.

Let's not forget battlemages. Probably one or two of those on each artillery tower.

There also need to be ditches to funnel away cloudkill spells. If the city is on a hill, they could even use tunnels that would channel it to the base of the hill, right into the midst of the attackers.

[Tvtyrant]

Another one a high magic setting could do would be to make the city impossible to approach except through the gates. The whole city would be inside a pocket dimension with the only openings being the front and rear gates, with an illusion of the city placed over where the city should be. You could even put a trap city overlayed with the real city, so trying to break in you find a city of zombies and ghosts instead of the real one.

[Storm_Of_Snow]

And what happens when the magic fails/is dispelled and the cities suddenly merge? :smalleek:

I could certainly see smaller versions of things like that as part of a cities defences - long duration or permenant pocket dimensions as bunkers for the civilians or secure storerooms for supplies in case of a seige (Magnificent Mansion for example), escape routes for the rulers or trapping enemies that have breached the walls (Maze).

[pwykersotz]

Many of the defenses you've laid out are your typical historical 'medieval castle defense systems' - which makes perfect sense for a fantasy setting. But one thing a fantasy setting has that the real world didn't have to consider in the n-teenth century was attacks from the air.

Since you can't realistically put a roof over your whole city (unless you do it using magic), you might consider building the city, or parts of it, either underground or into a hill/mountainside. A natural cave system that has been improved upon would make a good start.

In my world, this is why there are so many large and complex dungeons.

[Mr.Moron]

If your world has big flying creatures, casters that can cast flying spells, airships, powerful magic (like fireballs) then city walls need to have some kind of energy barrier or other supernatural protection. There's no reason to build castle or walled city in world with these things unless the walls can also protect from these things, and mundane walls as we know in our world wouldn't.

My favorite go-to example is The Paling from the video game Final Fantasy 12 where all major walled cities use central tower staffed by concentrating casters linked to walls to project a barrier around the city.

Walls are meaningless where every dragon, griffon and mid-level wizard can go over them.

[redwizard007]

If your world has big flying creatures, casters that can cast flying spells, airships, powerful magic (like fireballs) then city walls need to have some kind of energy barrier or other supernatural protection. There's no reason to build castle or walled city in world with these things unless the walls can also protect from these things, and mundane walls as we know in our world wouldn't.

My favorite go-to example is The Paling from the video game Final Fantasy 12 where all major walled cities use central tower staffed by concentrating casters linked to walls to project a barrier around the city.

Walls are meaningless where every dragon, griffon and mid-level wizard can go over them.

This is really dependent on the specific world.

In low magic settings traditional castles and walled cities work just fine. It also increases the terror of dragons. Batista and archers should be able to dissuade persistent aerial attackers. The main threats though, will be hordes assaulting or besieging armies. Those are threats real world defenses do just fine with.

In mid magic campaigns you are seeing wizards both assaulting and facilitating assaults, moderate flying attackers, traditional armies, fantastic beasts, and monstrous humanoids... that makes defense a cast iron #$%@%. In a campaign like this you need to either hand wave some aspects of defense, limit possible attackers (and thus tactics,) or inflate the city's defense budget astronomically. With enough scrolls, wands, and casters a city can put up a pretty good fight. Enough that it might dissuade direct assault. Wards in key locations to prevent scrying and teleportation are a must. Multiple layers of walls will help deplete attackers' resources, ideally with wards worked into key walls to prevent bypassing them via spells. I wouldn't worry too much about spells bringing walls down, it's inevitable in most magic systems but will deplete attacking resources and reveal the casters for a counter strike. Multiple strong points from which defenders can counter attack are absolutely a must, ideally with stockpiles of scrolls and wands (heavy on dispelling and disrupting magic.) Flying defenders and quick response teams (PCs) will carry the burden of stopping the attack while static defenses and traditional forces slow the advance and funnel attackers into choke points and killing fields. The key is going to be flexibility which is traditionally not a strength of defensive strategy. I'd run a defense of a mid-magic city as more of a series of counter attacks than as a set piece battle.

High magic campaigns are all together different. Walls of force, pocket dimensions, endless food stores, etc. War becomes a question of "what can I break?" Strategic sabatoge is going to be far more important in weakening a city's defenses. Defending key weaknesses or access points will take precedence, but exactly how is going to be specific to the magic involved.