What kinds of techniques or mechanisms, fantastic, magical or scientific, would make it so that an attacking army would take far less losses storming a castle/walled city than it would by standing outside of it and attacking it with siege engines?

A few things that come to mind would be some sort of magic bubble shield that protects against wall breaking siege engines, or maybe super powerful defensive artillery that would allow the defenders to attack and break up an attacking army if they were to simply stand about.

Another thing to note is that it would be acceptable if the cities/castle have reasonably easy ways of gathering/processing food within itself, so that the starvation of the defenders would take quite some time.

Besides that, another idea to toss up could be that it is naturally unsafe to be outside of a castle/city walls for prolonged periods of time, and that an attacking army would then also need to be able to deal of fierce local flora and fauna, or some other thing like the castle is suspended in the middle of the volcano, and the volcano could erupt at any time, wiping out an attacking army, but the castle is designed such to be alright against such a thing.

I digress; what could be good to promote bloody storming over boring, practical, safe sieging?

PS: I rather have it that in this setting, due to the presence of certain things, it is actually more costly in terms of life to siege, and that storming a castle is safer for the average soldier.

  • 2
    $\begingroup$ After just reading the headline, my thought would be to yell "donuts!" $\endgroup$
    – JDługosz
    Feb 2, 2015 at 12:14
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    $\begingroup$ Bye-bye, boys. Have fun storming the castle! $\endgroup$
    – KSmarts
    Feb 2, 2015 at 14:48
  • $\begingroup$ Are we to assume cannons are not available to breech the walls? $\endgroup$
    – Schwern
    Feb 2, 2015 at 18:22
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    $\begingroup$ Are you looking for a reason why a single castle was stormed instead of waited out, or are you looking for a world where castle storms are common practice due to a particular reason? $\endgroup$
    – Twelfth
    Feb 2, 2015 at 23:23

10 Answers 10


In a word, "winter".

I know that extreme climate has been mentioned but if you go back in time a few hundred years, feeding a few hundred troops let alone a few thousand while stranded in the middle of no-where outside an inhospitable castle was a mean challenge. Even in Europe, it did not need to be an extreme winter to end a campaign. The oncoming winter would lead to to issues making storming the castle a make or break option.

  • As mentioned, lack of food.
  • Lack of heat. Admittedly, cutting down the local forest would do much for this but still, a pitched tent and a huge fire is no replacement for a warm, dry bed in a house or even a barracks.
  • Hygiene. Again, mentioned before but sanitation would be a serious issue here, probably not much in the means of medical care and should a winter disease such as influenza were to rear its head in camp such as this, the effects could be devastating
  • Morale. The longer the troops have to sit around in the cold and wet with little food, watching their colleagues grow sick, the greater the likelihood of some kind of rebellion, especially from any mercenaries/hired arms who are only here for the spoils. Even if no mass rebellion, desertion would also start to become apparent.

A wise leader would be aware of this and would have to make the decision of whether to risk everything and storm the castle or to return home empty handed and face the embarrassment of failure.

Of course, abandoning the siege would then reduce the likelihood of the troops wanting to go on another raid next campaign season not to mention swinging public opinion against the leader making this a very difficult call to make. However, the later this decision was put off, the greater the chances of casualties, not only from the aforementioned factors whilst encamped but also from further complications caused by winter's progression during the journey home.

As mentioned earlier, if a particularly harsh winter were to come early then taking the castle might be the only way to survive short of surrendering to the forces inside the castle.

A few other miscellaneous reasons:-

  • If there was a "do or die" culture then risking everything on a castle storm at the end of the campaign would make sense. A slim chance of success vs freeze/starve to death vs guaranteed public execution for a failed siege would probably encourage people to storm the castle.
  • A different time limit e.g. the castle is holding the pregnant queen captive. You must storm the castle to rescue the queen before she gives birth to make sure that the child is not harmed.
  • This is not the only castle to take on your to-do list this campaign

The above are all reasons why you would have to storm the castle, even if you didn't really want to.

However, there are reasons why you may want to storm the castle:-

  • Technology. sappers are a prime example, I believe it was during the Crusades that the Arab forces undermined a Crusader castle and rather than destroying "such a beautiful castle", instead showed the garrison leader what they had done and earned a peaceful surrender. Even without going to this extent, it would only take a few weeks to dig under one wall. Burn the supporting struts in your tunnel and the wall falls down. Now it becomes an almost equal fight as much of the defenders' advantage is lost.
  • Locating an entrance. While setting siege to the castle, the secret entrance the castle's food gatherer's use might have been discovered. Maybe the stream that flows out of the castle can now be waded upstream.
  • Knowledge. Maybe the last day of October is some local ceremony/celebration that involves everybody getting blindingly drunk at the end. What better a time to storm a castle than when most of the defenders are barely conscious?
  • Sickness. Possibly plague strikes inside the castle (catapulting those rotting cows inside the walls seems to have worked or was it poisoning the stream that flows into the castle). Either way, sick defenders are much easier to overcome than healthy ones making it a great time to storm the castle rather than wait for them to get better.

I would conclude that there are credible political, seasonal and situation based reasons why storming a castle may be better than setting siege to one. Some may incur fewer losses but overall, if you can feed and care for your troops, a siege is generally the less likely to incur losses even if it costs the most and takes the longest.

  • $\begingroup$ Excellent answer, although I'd also suggest giving the assault a considerable reward. ie the price of success may be high, but the rewards are even higher: you gain territory AND gain the funds to rebuild your army. $\endgroup$
    – Jon Story
    Feb 2, 2015 at 14:57
  • $\begingroup$ Oh, and the risk of the siege being lifted (ie an approaching relief army) could be used to give a realistic time limit, or alternately a need to advance further into enemy territory - which would make an enemy stronghold (full of men) in your rear a complete liability and danger to your supply lines/lines of reinforcement $\endgroup$
    – Jon Story
    Feb 2, 2015 at 16:41
  • $\begingroup$ castle are often built on rock to stop the digging under. $\endgroup$ Feb 2, 2015 at 20:42
  • $\begingroup$ I am such a sucker for such big and long answers. Really big and detailed. I like the inclusion of possible failure as a motivation, as well as the cultural and morale aspects of an attacking sieger $\endgroup$ Feb 3, 2015 at 2:31
  • $\begingroup$ The usual way in mediaeval times was to bribe someone to let you in. This is quick and easy and much cheaper than sacrificing your troops. Instead of bribing the letter-in you could take family members hostage or whatever. $\endgroup$
    – RedSonja
    Feb 6, 2015 at 13:54

Besieging a castle was also a risky enterprise, due to:

  • Diseases: think of thousands of men camping together without proper sanitation.

  • Risk of attack by relief forces. Even if the outside force is not enough to present battle, they may attack your foraging parties, reducing the income of supplies. This would be my favourite. For example, the crusaders of the First Crusade were in the brink of starvation when they stormed Jerusalem.

Other reasons:

  • Some castles had a harbour. Unless the attacker had a fleet with them, besieging them would mean nothing.

  • Also, political considerations (avoid time to your enemy to gather allies, lack of money to pay your troops, need of a quick victory because there is unrest back home).

  • And additionally, it may be that your enemy has some other advantage that will vanish with time (v.g., the enemy numbers are largely untrained militia, but every day it passes they are better trained, or a section of the wall is already damaged and the defenders are repairing it).

  • $\begingroup$ Good points all around, but how quickly can an untrained rabble be trained, to the point that they were considerably better than untrained, and the political considerations is a good way to add a time constraint for the attackers $\endgroup$ Feb 2, 2015 at 0:00
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    $\begingroup$ There is no hard limit; if you allow to train for two weeks they will have double the training that if you stormed the castle after the first week. And in fact, I would say that training will follow the law of reduced benefits (the first days will be enough to make them from 20% effective to 45% effective -not disbanding and facing the enemy-, the following week they will get to 60% -pointing the sticky end to the enemy-, the next one 70% -moving without cutting your comrades arms-, etc.) $\endgroup$
    – SJuan76
    Feb 2, 2015 at 0:04

Be careful going in this direction. It has the potential to make your story feel instantly fake.

Consider why castles are created in the first place. The single solitary purpose of a castle is to give the defender a positional advantage against attackers. Against a lesser wall, it is often effective to storm the walls. Castles were designed with the expressed intent of making this difficult to do.

So if we keep the abilities of a castle to fend off storming fixed, but make them harder to siege, we make them virtually invulnerable. They were extremely good at stopping stormers, and now they're even better at stopping siegers.

On the other hand, if we weaken then to storming, then the question of "why'd we build this dumb wall of rock in the first place" starts to show up. There has to be another dimension to the story.

Castles were designed to be an unmoving defender on the battlefield. If we want to keep castles in existence, but make them weak enough to be stormed, we're going to need a third player on the battle field.

Time is one good force. One of the major issues with a siege is that it takes a lot of time. Any effect which prevents protracted engagements is effective. You suggested several effects (werewolves striking on the full moon seems particularly effective). However, you don't even need to resort to magic. Consider a world where fluid movement of troops is the norm (more like modern day combat, less like medieval combat). The construction of siege engines is an expensive endeavor. While one is doing so, ones army is no longer defending their citadels. If there were 3 parties in balance, any protracted assault would leave your own home weak to attack.

On the other hand, if magic is an option, consider a castle protected by a shield like the shield generators from Dune. Dunes generators were explicitly written by Frake Herbert to take ranged weapons off the table for his story. A fast moving object was stopped, but a slow moving object is allowed through. This created an entire school of combat which sought to slowly get a knife under the shield to strike with. Scale this concept up from personal shielding to army-and-castle sized and you have a solution which refutes large ranged attacks, but allows individuals to walk through the shield slowly. All you have to do is weaken the capabilities of a stone wall, or else you'll still have a stone castle preventing a storming army. Weapons that use vibration to crack stone might be an effective way to discourage relying on massive stone structures.


There isn't really that much of a question here anymore, you've basically answered yourself straight from the get go.

If the area around the castle is so dangerous that sitting around, waiting, for any amount of time would be disastrously dangerous, whether from meteorological phenomena, rabid wildlife or just environmental factors, then no one would ever even really think of sieging someone else's castle. In fact, then a new question would crop up: Why are they even attacking such a terrible place to live in the first place?

Its not even a matter of storming being better than sieging. If the castle was built, for example, to keep the environment at bay rather than any potential attackers, then you can imagine that being in the castle is more than just a matter of tradition. Its a matter of safety - you would not last long without the castle, just like those blokes standing about outside your walls right now, coincidentally castle-less.

  • $\begingroup$ I simply wanted to ask others if it was possible to add anything else onto my question. I already knew of things to promote storming, it would be nice to be able to get what other people think as well, and it would not be very helpful if people simply told me what I already know. As for your question of why are they attacking such a terrible place to live in is because the not-castle area is terrible, but the castle area is fine, it is desirable to take the castle area for themselves $\endgroup$ Feb 2, 2015 at 2:09

The problem here is not making it practical to storm the castle. There are plenty of ways, ranging from levitation magic to cannons with explosive shells.

The problem is making it practical without rendering castles obsolete. The purpose of a castle, or any defensive fortification, is to render direct assault very costly in terms of men. In order to encourage castle-building while still permitting assaults, you need to make assault mind-bogglingly expensive: you need to hire a small army of mages to levitate the assault force, sponsor a country-wide manufacturing effort to build enough cannon shells, and so on.


The purpose of a siege is to starve out the defenders and you have already touched on a mechanism whereby a siege wouldn't be "cost effective":

Another thing to note is that it would be acceptable if the cities/castle have reasonably easy ways of gathering/processing food within itself, so that the starvation of the defenders would take quite some time.

So, you could have walled cities that have most of their food production happening inside the city walls and a country side that is unable to support the attacking army then you have the motivation for storming the castle. You just have to come up with a convincing argument :)

Things that spring to mind:

  • Marauders - bands of outlaws that attack anything short of the castle. This would explain why the food production in inside the city walls and would mean that as well as there being no farms for the attackers to feed off, they would also be a distraction and extra drain as they'd need to defend against them at the same time as trying to maintain the siege.
  • Volcanoes that prevent farming, but keep caverns under the castle warm enough to grow food.
  • Extreme climate variation.
  • Dragons - pretty much the same reasoning as above.

Though these last two don't really fall under the tag :)

  • $\begingroup$ No need to worry to much about trying to cram in all the tags, I just wanted to leave the options open $\endgroup$ Feb 1, 2015 at 23:51

Ill start by addressing a few of your assumptions.

Few things that come to mind would be some sort of magic bubble shield that protects against wall breaking siege engines, or maybe super powerful defensive artillery that would allow the defenders to attack and break up an attacking army if they were to simply stand about.

Ill address magic later but defensive artillery would still have a max range, this means that the besiegers simply have to back up a little bit farther. Admittedly it may take a few more people to maintain the siege or be easier to smuggle goods in but that isn't going to drastically change things.

Another thing to note is that it would be acceptable if the cities/castle have reasonably easy ways of gathering/processing food within itself, so that the starvation of the defenders would take quite some time.

Not really acceptable no. Perhaps one or two cities on the planet can afford to do this, but it should not be common. Farming takes A LOT of space. The cost to wall off farmlands would be massive, not to mention manning the walls. The best scenario to do this in my mind would be a fairly small settlement but then again a small settlement isn't going to be that hard for a large army to seize. For reference it looks like it takes about 1.2 acres to feed a person annually. (admittedly this is the rate for American dietary standards and could be down graded a bit) but again this is going to get more challenging as the settlement gets bigger.

So onto the main point

Tons of options here. I will break this down into science based, and fantasy based.

Lets start with science based.

  • The castle is minimally defended. This can simply be its faster and less costly in the long run to storm the castle. On the other hand it may be that another army is inbound to relieve the castle defenders.
  • Lack of resources. This can be food or water or both. Geography plays a big role here obviously. Protracted warfare can also cause this problem. If no one has been farming for years you can't really live off of raiding the countryside.
  • Good ol fashioned anger. If you mustered your army on the premise that the enemy did something terrible (true or not) you may need to capitalize on that before people start to question the validity of the situation.
  • Off the boat. Naval invasions are dangerous in that you have nowhere to retreat. Find a weak (for whatever reason) coastal target, and seize it immediately so you have a place to fall back to in the case of a loss or tactical error.
  • Weakly allied forces. You brought some...friends along to the fight. But really you tend to fight each other a lot and this is a temporary alliance. Waiting around for months things are likely to get out of hand and the defenders may end up just getting a good show as the two (or more) parts of the besieging army destroy each other.

I am sure I could think of many many many many more but hopefully these examples have you thinking. Simply put you need to create a scenario where the expedited capture of a location is more valuable than the extra lives lost to storming the castle versus besieging it.

On to Magic or simply the fantastic

  • Magical defenses. The beauty of magic is you can do pretty much anything with it. Some common defenses are barriers, for example on gates or counter siege artillery. The full on protective bubble is an interesting idea but I find it less believable simply due to the massive amount of energy that would be needed to maintain it...plus is sort of a cheap gimmick and makes battle way less dynamic.
  • Spells to improve food production. Perhaps you can have your walled in farm by some combination of tiered growing areas and magical light.
  • Magical beasts. As you mentioned you could have the flora/fauna put up a fight against besiegers. There are few animals that will prey on humans, especially humans in large groups in the real world, but a few magical life forms and sure why not.

Really when it comes to magic your imagination is the limit. I would try to avoid things that are to good to be true, or so fantastically powerful it just doesn't seem fair. The magic bubble for instance. If mages can make an entire army meaningless then whats the point of even having armies. I guess the point is, that kind of magic should be exceedingly rare if it exists at all.


In general, the only "long term" way to make storming castles practical is to develop a technology that negates the castle's defences. The high curtain walls of castles were there to prevent attackers from climbing over using the primitive siege technology of the time, and provide an advantage for the defending archers (high, protected fire positions).

The Infantry Revolution starting in the mid 1400's provided weapons that allowed large bodies of relatively untrained men to take to the field on more equal terms with knights and fighting men who had trained of an entire lifetime, but blocks of pikes and crossbows don't help much in besieging or storming a castle. In our history, gunpowder weapons that could reliably breach the high curtain walls of a castle made castles obsolete, until new styles of fortifications were developed to defeat cannon fire. Vaubin forts in turn needed new technologies to overcome, and so it goes (American "Third System" forts built at great expense prior to the Civil War were systematically demolished by rifled, shell firing cannons, and the great concrete forts of World War One were smashed by superheavy high angle fire, while WWII era forts were simply bypassed (the Maginot Line) or attacked by paratroopers (Eban Emael).

So while logistics or political factors may "force" your commander to consider storm vs siege, only the liberal application of "new" technology will make storming seem to be a reliable or viable option.


If it's a one-off, i.e., you need to convice one particular army to storm the walls once rather than to make it common practice across generations, then:

Have a much larger enemy army incoming in a short, known amount of time. The sieger's best hope is to capture the castle sooner, and without great damage, and use it for defence.


The main reason for making a siege impractical is pretty prosaic. Logistics.

An army contains a lot of men and horses. These need to be fed. A lot. A decent sized army is about the same scale as one of the larger cities in the realm, and it moves around. Your supply men will have to find supplies, and wagons to carry them, and extra food and fodder to feed the men and horses pulling the wagons to boot.

Then you have to continue doing this every day as long as the siege lasts.

For all but the most organized societies, this just is impossible to accomplish. So it is assault, or give up and go away.


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