How does a fortress defend from magical attacks?

Hey, everyone. Joined the forums to ask this specific question.

In standard fantasy rpg, how do castles/keeps/fortresses prepare their defenses to repel powerful magical attacks. I was having this discussion with a friend, and neither of us could come up with a satisfactory answer. I would assume that a standard resident mage (or group of mages) would be necessary to counter attacks of that nature . . . but is there anything else keeps do to prepare themselves for such a thing?

Thanks for any help . . .

Other mages? magically enhanced structures, magic null fields, anTi mage experts.

It probably strictly depends on

1. Rarity of mages in fiction
2. Power of mages in fiction

But yes, I'd imagine if mages are relatively common place and or powerful other mages would be used to counter them.

Depending on what sort of fiction it is there may also be non-magical creatures/people adept at hunting down mages. Or even some sort of creature/noise which debilitates magic users/magic.

Assuming spell casting takes a while, no defensive barriers are set in place and mages require to be in range of the fortress they wish to blow up; nothing stops complicated incantations better than a rain of arrows. Or shock troops and ambushes. Hell, train dogs to kill and unleash them in a unit of mages. The only way mages work well is if they have an answer for everything (like defensive barriers and shit, or quick-casting spells, or are both armed and armoured, etc.) or they are very well protected by their fellow troops (and even then; archers.)

Expanding on what MelonHead said, it really depends on the setting.

If you are assuming a fortress like you see in Europe, made of stone and intended to be defended (and attacked) by people with pre-gunpowder weapons, suddenly introducing "magic" into the situation is a seriously destabilizing factor. If you take "magic" as being the sort of usual fantasy wizard fare - fireballs, lightning, etc. - then what you're doing is creating a situation not unlike "what if one side had a couple people with modern firearms, and knew how to use them?"

If your starting conditions are "a medieval fortress with defenders, in a setting that does not have magic, are suddenly forced to deal with someone who commands the elements at their will," the obvious (and only) answer is that those defenders will likely be slaughtered, without ever understanding what exactly was going on.

If you extend the question to a campaign, where one side has the First Wizard Corps and the other side merely has a functional military, you start to have long-term questions. The first defenders would not fare well; a combination of fear (they don't understand what's attacking them) and utter lack of tactical doctrine to deal with it would make their defeats likely swift and total, save for prisoners. That said, mystery is not something that persists in warfare for very long - you have scouts, you have intelligence, you have spies and defectors. The fog of war is a real thing, but it is a fog, not an impenetrable wall.

Sooner or later the defenders would figure out why the other army is trouncing them, and why such wild stories are coming from the survivors. To wit: The Other Guys Have Fucking Wizards, Man.

This could cause one of two things - the side without Fucking Wizards, Man (FWM) could suffer a morale collapse, due to a feeling that they have no way to fight back. This could turn into a protracted retreat cycle where in the best case the side without FWM surrenders to terms dictated by the side with FWM, and in the worst case is utterly destroyed by an unwillingness to surrender, but an inability to meaningfully fight back.

If the defenders (the side without FWM) have sufficient manpower, morale, leadership, etc. to mount a meaningful defence, in a large-scale engagement they may find that the FWM make less of a difference than the might in a static assault.

Before I go on, I should point out that I am assuming that the FWM:

- Are not deific/angelic beings (e.g. Gandalf)
- Are mortal (If long-lived, perhaps)
- Are fallible
- Are not someone who can crack a planet with a sneeze (I never understood how meaningful conflict was supposed to come about with that)
- Are comparatively uncommon, but fairly powerful

In other words, let's assume that a typical group of FWM is some smallish group of magi (let's say 1% of the attackers' total fighting force) on the order of the Wizards of the White Council, from Jim Butcher's Dresden Files.

In a large-scale encounter, the FWM would act as force multipliers to whoever was within their range of influence. This would certainly be longer than a man with a spear, and certainly more destructive than someone with a bow. It is unlikely that they would be able to sustain the destructive capability of a siege engine, provided siege engines were being employed in the engagement (I'm not certain how likely this is, but it is probably Not Very).

At this point the question becomes one of tactics. If the commander of the army with the FWM is a very stupid person, he could allow the FWM to become overextended or exposed in an disadvantageous way. At this point the enemy army would have an opportunity to discover that the FWM are mortal, even if the bulk of them get away, which would likely result in a huge morale boost. Even if the FWM's commander is a very smart person, the FWM won't be able to reinforce a line forever (just as a big man with a sword can't swing it forever) and at some point they will be exhausted, reduced to purely 'normal' methods of attack and defence. If the FWM's commander has not turned the field decidedly to their advantage at the point where this happens, they will be subject to the conventional capabilities of whatever era they happen to be in.

In other words, if the defenders have reserved their strength and made a deliberate point of tuckering out the FWM in some manner, it becomes a more or less standard question of (presumably) medieval warfare.

Conversely, if they have not, they may be slaughtered like the defenders of the fortress several paragraphs ago.

Regardless, after this war, any military that does not have FWM would probably start investing a lot of money and time in extremely precise ways of dispatching individuals, in order to reduce the impact FWM could have on a conflict. One form this could take would be a network of spies and assassins, whose job it is to be more or less suicide agents to stab FWM in the neck before they can bring their powers to bear on any particular conflict. Considering the damage FWM could do to a side without them, recovery of the agent would likely not be huge on the priority list; the loss of a highly-trained and expensive operative would be a comparatively small price to pay to ensure that whoever is attacking (or might attack) you does not have FWM.

In return, armies and nations with FWM would probably become paranoid and rigidly regimented in order to more easily find spies, assassins, and other agents.

Is it starting to look like the Cold War between the United States and the Soviet Union yet? ;)

-----

Other than that, the question becomes purely one of starting conditions, and can't be extrapolated any further than that. Are mages common? Well, the way you defend from magical attacks is to have your own Wizard Corps stationed where you're likely to be attacked. Are there materials that resist magical attack? Use those to build your fortresses. What if they're very expensive? Use them to armor only your capital and areas of strategic importance. What if there's only one piece and it must be in the hands of the last pure maiden born on a full moon in the last week of November on a Thursday? Well, you'd better make sure that girl is on your side.

For argument's sake, let's just say that a spell exists that grants flight for about an hour, 1-in-1000 people are mages, and the spell can't let them move any faster/carry any more than they could if they were moving on foot.

Conventional fortresses will be designed to maximize the flow of your forces moving out, while simultaneously minimizing the chance of enemies from getting in. You'll see lots of towers and arrow slits, and almost all entryways will have both portcullises and murder-holes. Exterior walls are made rather thick, to increase the amount of time needed for aerial battering rams and siege weapons to penetrate your defenses. The interior will be a network of narrow passageways designed to deny flying enemies the usefulness of their magic, and funnel them into spacious rooms to be shot to pieces by your forces.

Sorties would be done by armored aerial units with hot oil, poured out onto the ground troops from altitudes that weaken most projectiles fired from below. Combined with flaming projectiles from the fortress, and you've got yourself a barbecue. Aerial units would do well to spread out, unless their collective manpower is needed, minimizing the risk of a volley taking them all out. Flying forces engaging one another would battle for altitude superiority, the chance to accelerate to blitz their foes via free-falling, and disable their targets with nets before barraging them with projectiles.

That's just one example.

This is all great stuff! I particularly enjoyed Naril's post, but they were all helpful. I'm quite familiar with the structure and tactics of castle(etc.) warfare in the real world, but the thought of a magical attack had me stumped. Regarding the particular stronghold we're working on, an aerial force (Giant Harrier riders, Dragon riders, etc.) probably isn't feasable, so they need an alternative method. Again, there were some good ideas above!

Assuming that power and amount are inversely proportional.
The population of france in 1086 (Right before the crusading era) was around 13.4 million people. (Wikipedia)
if 1/1000 people were mages, that would make 13,400 french wizards.
Needless to say, if there were a tenth as many wizards there would be plenty of wizards to give every landed noble a wizard. If there were a hundreth, scarcity will start to set in. Nonetheless, every major noble could still have a court wizard under that circumstance.
Now if there were a thousandth, things will start to get trippy. So 1/1,000,000 born would start to cause problems. There wouldn't be enough wizards to go around even for the major nobility!

I would personally go for the simple approach and say 'other mages'. In the same way that in, say, Star Wars the best way to defend against Sith attacks is to have a Jedi around. Typically speaking, Wizards/Spellcasters tend to be in a class of their own that the average footsoldier isn't going to -want- to get involved in, let alone be able to. Sure, you can take one out with a well placed arrow or two, but for the most part an arrow isn't going to stop the arcane fireball that's currently hurtling towards you at breakneck speed. The only answer for that.. more magic.

As for alternatives to having a resident wizard/group of wizards? Enchantments, runes... magical stuff that doesn't need a wizard nearby in order to still be magical. If I were rolling a fantasy setting and this were a question that arose, I'd probably go for runes. Firstly, if you've got a fort or castle made of stone, you etch some runes into that stone, those runes aren't going anywhere fast. No enemy wizards are going to be able to come along and just wash them off, those runes are there for -good-. Second, enchantments are, I imagine, the kind of thing that might wear off and need renewing every year or few years? Whereas a rune carved into the bedrock of your castle might only need to be re-carved every fifty years or so. If you're building a castle to last, for my money, it'd be runes.

Magic repellant materials, like an alloy which can absorb and dissipate magical energy akin to a lightning rod type of idea.