For millennia the Arbol and the Byrond clans have engaged in bloody warfare. A benevolent wizard who is passing by and hears of this decides to stop them once and for all.

He casts a powerful spell that makes the clans invisible to each other. This includes their clothing and any artefacts (British spelling) they are carrying including weapons. It also applies to substances such as dust, powder, solids or liquids that gather or are thrown at them and stick. In other words they cannot be made visible by some trick.

The wizard leaves this non-magical medieval realm believing he has done a great service to all. Unfortunately the clans still want to carry on their vendettas.

How can they fight if they can't see each other? What tactics could they use?


The clans are not invisible to themselves nor to anyone not involved. They are only invisible to the opposing clan members or opposing mercenaries or opposing agents such as trained animals. As stated, no tricks such as throwing powder will make them visible. The wizard has excluded that.

Clarification - if you throw powder and it sticks then it also becomes invisible. The part that doesn't stick will presumable leave a temporary 'hole' but the opponent can then dodge.

They would be given away by brushing against things that aren't attached to them in some way. A branch that got caught in their clothing would become invisible but a branch they brushed against would not.

Trying to join one of the clans in order to settle your own grievances would be treated with great suspicion. You might be a spy. There are very strong bonds of blood in these clans. Marrying into the clan would require a thorough check into your background.

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    $\begingroup$ Would war tents, houses, and other stuff like that be invisible 24/7? $\endgroup$ – Andrey Dec 3 '18 at 21:48
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    $\begingroup$ What about the ground? For instance, what if they're walking through snow? $\endgroup$ – Acccumulation Dec 3 '18 at 23:31
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    $\begingroup$ Can they see each other shadows? $\endgroup$ – user6760 Dec 4 '18 at 3:01
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    $\begingroup$ @Andrey - Their footprints would be seen in snow. Anything they are not carrying is visible. If they drag something it is still visible. It has o be lifted completely off the ground. $\endgroup$ – chasly from UK Dec 4 '18 at 11:38
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    $\begingroup$ @user6760 - Good question. I think I'm forced to say that they can see each other's shadows or there would be a paradox when other people looked at them. A shadow is a lack of light and as far as I can see, you can't make something that isn't there invisible. So yes they can. $\endgroup$ – chasly from UK Dec 4 '18 at 11:47

19 Answers 19



As a general rule in long-term, low-intensity conflicts like this, you don't target the other side individually, you target their stuff. This has a number of benefits: they need to put effort into getting new stuff (instead of fighting you), they needed that stuff to bring up the next generation of people to fight you (usually by "stuff" we're talking food, or other vital supplies), and of course you can get their stuff.

In this scenario, this has the added benefit that their stuff is not invisible. On the other hand, when you pick it up, it becomes invisible! Plenty of thieves would give their right arm for that trick. (Or somebody's right arm anyway.)

Even if you can't steal things, you could destroy or despoil them. If the enemy has cattle, maybe that's a little tricky to walk off with (although it's possible...) but it's still a big fat target.

On defense, you have fewer options. Stopping raiding parties is hard enough when they're totally visible! Aside from raiding them even harder, I'd expect them to specialize in physically-triggered traps. The clans aren't intangible, after all, so things like tripwires, pressure plates, pit traps, etc. are all fully functional. Big static defenses would also be valuable: a wall around your stuff that's difficult to scale, basically.

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    $\begingroup$ Well, if it doesn't, then you have to run before somebody notices their chickens carrying themselves out of the yard. :P $\endgroup$ – Cadence Dec 2 '18 at 11:09
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    $\begingroup$ it rather has to, because if it doesn't then the wizard's spell is no longer working as advertised, and the 'things attached to them' are making them visible. $\endgroup$ – Giu Piete Dec 2 '18 at 11:21
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    $\begingroup$ You're right. I withdraw my objection. There is a potential problem You can't 'steal' a house just by touching it. You must carry the thing on your person. Therefore a chicken would cluck but not be seen. A cow would stay visible unless you were strong enough to carry it. A team could perhaps accomplish this. $\endgroup$ – chasly from UK Dec 2 '18 at 11:25
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    $\begingroup$ If you want to get a sense of how important going after cattle could be (and how to build a story around it on a mythological scale), definitely read the Táin (in English, grab either the Kinsella or the Carson translation - en.wikipedia.org/wiki/…). $\endgroup$ – James Moore Dec 2 '18 at 19:06
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    $\begingroup$ Might I add, a great defense to people jacking your stuff is (whenever practical) carrying as much of your stuff with you as possible. $\endgroup$ – user45266 Dec 3 '18 at 5:25

Attacking opposing camps has already been covered - aim for their belongings, not their (invisible) people. However defense is the important flip side.


  • Trip wires with bells attached with give away an invaders position (this could be countered by making animals - perhaps a herd of deer - run towards the camp)
  • Bells on doors - they're already close at this point but you know where they are
  • A string of bells with tar (or some other sticky substance) on them, once they stick the enemy has to either stop to remove them and reveal their location or keep move slowly to avoid disturbing the bells

Other objects

  • Objects that move easily (marbles, for example) would give away the movement of an enemy as they roll away from them - even if the initial object is invisible the others won't be
  • Watching for what isn't there: all those materials you mentioned (dust, oil, powder) would be invisible if they touched the enemy so the fact you can see those means your attacker isn't there

Using guard animals (dogs, etc)

  • Their other senses are much better than a human's - using their reactions as an alarm would also be useful

Use the invisibility

  • If any object you touch becomes invisible to them you could have razor wire at neck height and a watchman touching one (blunted) end, providing you with an invisible razor wire (this could also be used as an attach, sneak into the enemy camp and set traps like this)


  • A hole in the ground or a snare trap will capture the enemy, you might not be able to see them (or your trap) but you'll know they're there because the trap was sprung
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    $\begingroup$ Speaking of guard dogs, one question that occurs to me is: if a person (or animal) serves one side, does the curse then start to affect that person or animal, too? $\endgroup$ – bobtato Dec 2 '18 at 18:29
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    $\begingroup$ That is a good question (@chaslyfromUK?) I was under the assumption they couldn't see them either (which is why I relied on other senses) but I guess only the op will know $\endgroup$ – Lio Elbammalf Dec 2 '18 at 18:58
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    $\begingroup$ Best offense is a good defense? $\endgroup$ – FreeElk Dec 2 '18 at 19:29
  • $\begingroup$ If the curse works at all in one direction then it also works in the opposite direction. There is never any one-way. $\endgroup$ – chasly from UK Dec 2 '18 at 22:16
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    $\begingroup$ I really like the idea of using the invisibility to set very dangerous traps. Nice touch. $\endgroup$ – Sam Weaver Dec 3 '18 at 22:47


Area of Effect. Carpet Bombing. Indiscriminate widespread attacks.

You know roughly where the enemy is, but can't see them. So you attack the whole area.

Have your archers fire quickly and somewhat randomly. Heck, in open field war, archers didn't generally target opponents, they just fired quickly into the mass, expecting to hit something.

Even better, get your catapults and trebuchets, and instead of loading them with a single large rock, fill them with a number of head sized rocks. And depending on the situation (availability and possibility of out of control fires), mix in some incendiaries.

You don't have to hit specific people, so long as your barrage takes out some of them.

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    $\begingroup$ "If brute force doesn't work, you aren't using enough." - Schlock Mercenary $\endgroup$ – Cort Ammon Dec 2 '18 at 17:56
  • $\begingroup$ Seemingly effective, but if you hit some enemies, the rest are still out to get you. I like the idea though, of attacking the entire area. $\endgroup$ – iostreamerX Dec 3 '18 at 5:29
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    $\begingroup$ AoE = area of effect. Should be noted in the answer $\endgroup$ – person27 Dec 3 '18 at 14:45
  • $\begingroup$ "Frustrated by being greatly inconvenienced in maiming each other, the opposing factions turn to the path of industrial large-scale production and of scientific research on means of mass destruction; eventually they end up in the nuclear race against each other with predictable results for the whole world"... I'd actually like to read something like that. $\endgroup$ – Joker_vD Dec 4 '18 at 11:12

All your bases are belong to us

Attacks will have to be carried out based on known locations. The clans could pore over the map of their city, and check individual houses. Finding a residence that looks unoccupied, they can then question the locals about why it is empty. If it's not empty, then they've found a suspected location to nuke.

This may however lead to a lot of collateral due to false positives, or the other clan member may just not be home.

The attacker holds the advantage in this scenario though, as the base is known but not where the attack is coming from. This will lead to a long drawn out battle where each clans places of residence and bases of operations are slowly taken out.

EDIT: In case these clans are living in closed communities, this method just scales.

You'd then have to hire cartographers to look for anomalous villages. The settlements of the opposing clan would look perpetually "just been abandoned". The houses they live in, their fields, food set on the table, these things don't disappear. There will be random items constantly appearing and disappearing in the village, and once found the settlement would basically advertise itself to be the other clan's.

The searching process can also be augmented by getting known maps of the area as stated before and checking already marked villages.

Problem with this is, whichever clan is found first will be annihilated. The advantage lies completely with the attacker, and having no collateral to worry about, can proceed to completely raze the opposing village. The most likely tactic would be to set fire to the houses at night, taking maximum population, then burn the fields and food caches, and maybe set lesser traps on obvious exits to harry survivors.

Of course, that possibility might occur to the clans, and they'll modify their residences to suit defense.

  • Scatter the clans into smaller villages.
  • Set up efficient communication system between the villages. Horses will most likely be killed, probably poisoned, in the prelude to the raid. So there would have to be riderless runners. Hidden passes between the villages could be set up. Messenger birds could be trained (birds are much harder to target than horses I am assuming)
  • Set up a constant warning system, with scouts hiding in the surrounding terrain with no obvious markers. If an attack happens in one village, the scouts immediately send message to the others to scatter.
  • As they might have to run at a moments notice, packing might not be an option. The clans would probably contribute to hidden caches set up away from settlements that can be accessed by escaping refugees.
  • $\begingroup$ How do you question the locals of the opposite tribe, when they can't see you? Even if they are not freaked out by invisible people talking to them, because they know what the wizard had done, they will know the invisible person isn't from their own clan. $\endgroup$ – alephzero Dec 2 '18 at 15:17
  • $\begingroup$ Ah, I mistook the meaning of Clans. Assumed it meant people with familial ties living in a larger settlement, like a town or a city, with both clans possibly sharing the city. Will edit answer to include this detail. I am unsure whether such a large edit is allowed, despite it remaining the same answer in spirit. If it isn't I'll roll back. $\endgroup$ – optimisticOrca Dec 2 '18 at 18:14
  • $\begingroup$ I interpreted the OP as the clans are only invisible to each other. To anyone not a member of either clan, everyone is as visible as normal. $\endgroup$ – Baldrickk Dec 3 '18 at 10:29
  • $\begingroup$ True, and also to anyone involved, like hired mercenaries and such. $\endgroup$ – optimisticOrca Dec 3 '18 at 10:45

A "dirty" solution for Day 1: Line your troops up, swords out, and have them march in a row while chopping and swinging wildly at fresh air and being very careful not to hit anything they can see.

Something a bit more refined for future engagements?

  • Carefully trained, silent Bloodhounds, who can sniff out your invisible foes while remaining unseen by them.
  • Small bells in a sticky/adhesive goop - thrown at your opponent, they turn invisible - but not inaudible!
  • Train up assassins to pick out targets and avoid obstacles by sound. That wizard has provided you with a surplus of invisible ninja for your noble cause!

(Something that was not elaborated on - does the wizard tell the Clans? Or are they just pitched up, ready for battle, then wake the next morning to find their enemy is gone, but their tents remain. Scouts sneak in to investigate, then report back that they can still hear the enemy, but can't see them! How long until they realise that they are just as invisible to the enemy as the enemy are to them...)

  • $\begingroup$ The wizard does this overnight without any warning and just leaves them to get on with it. This isn't an organised war so they aren't necessarily in tents. They just continually engage in skirmishes when they encounter each other. Occasionally there are planned raids of each other's villages. Think of the history of inter-tribe hostilities in New Guinea and other places. Also the Capulets and Montagues in Romeo and Juliet. $\endgroup$ – chasly from UK Dec 2 '18 at 16:40
  • $\begingroup$ @chaslyfromUK - there's hundreds of years of examples from the UK, too - en.wikipedia.org/wiki/Border_Reivers. $\endgroup$ – James Moore Dec 2 '18 at 19:10
  • $\begingroup$ James Moore - Absolutely. I'm sure it's been a worldwide phenomenon for most of history. Even now we get football (soccer) fans fighting each other in gangs. $\endgroup$ – chasly from UK Dec 3 '18 at 14:12

I can't believe nobody suggested that yet:


Bacteria and viruses don't care if you're visible or not, they just jump from person to person.

Throughout ages there were many ways to spread disease among the enemy. By throwing manure in their water supply you can have a nice cholera outbreak. Rats and other flea-ridden animals are wonderful for spreading bubonic plague. STDs, once introduced, are nearly impossible to eradicate.

As soon as a disease strike one side, the other can declare "temporary cease-fire for humanitarian reasons" and send them aid. Such aid can be, for instance, blankets previously used by smallpox victims.

Just be careful - that kind of tactics happens to backfire more often than not... which makes a good story.

Further reading: https://en.wikipedia.org/wiki/History_of_biological_warfare

  • $\begingroup$ it's generally accepted that medieval societies didn't well understand biological warfare, and whilst a sword can cut both ways, trying to spread plagues with a medieval comprehension level almost certainly will, if one has any concept of ow to do it in the first place.. but.. it should be included in answer 'salting farms' and such also. $\endgroup$ – Giu Piete Dec 3 '18 at 8:43
  • $\begingroup$ @GiuPiete I wouldn't agree with this ... poisoning wells and more generally food and water supply has always been standard practice in medieval warfare; especially during siege-style events. $\endgroup$ – Tasos Papastylianou Dec 4 '18 at 15:54
  • $\begingroup$ It looks to me like you decided to disagree, rather than you actually disagree. I didn't say poisoning supplies etc didn't happen/that nobody had any idea of what the general concept was.. What I said was that it can be a double-edged sword. There is no 'edited' mark(and the answer states as much, and I had upvoted) so Idk why I felt the need to make the comment, but it's not wrong. $\endgroup$ – Giu Piete Dec 4 '18 at 17:00

Tactics would largely depend on the typical battle sizes and available technology level, so, without that, we are kind of stabbing in the dark.

At any rate, one thing invisible people leave is


Especially for defensive and ambush positions, have the enemy approach over a wide stretch of sand, mud or similar, and have prepared some concentrated ranged fire - catapults, Greek fire or maybe some avalanche, depending on terrain. Mud and sand have the extra bonus of not requiring a lot of preparation between battles, and they work well with sound alarms described in other answers.


Not necessarily a blizzard, but either a snowfall, sandstorm, waterfall or saturation of area with a load of other small moving particles would show clearly the places where they can't go -- emptiness where there shouldn't be any shows up the invisible people.

Goose down

As an alternative, when you are already in a combat situation, you could have some sacks of slow-falling material -- goose down maybe, but a bit wet to make it slightly heavier(?) -- to throw over an area, with some bowshot or other way to split the sack while it is in air above where the enemy should be.

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    $\begingroup$ Maybe not a magical blizzard as OP said "The wizard leaves this non-magical medieval realm" $\endgroup$ – person27 Dec 3 '18 at 14:51
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    $\begingroup$ Finally someone mentioning footprints! I thought of one clan enclosing its camp with moats such that any attacker/raider will get drenched and leave wet footprints upon entering the camp. If the water is somewhat muddy it should make it even easier to identify someone invisible in it. (And I bet it should be easy enough shooting at such a target. Additionally, they can be dead sure it's an attacker, as only those will be invisible - so no innocents will be harmed.) $\endgroup$ – Inarion Dec 3 '18 at 15:55
  • $\begingroup$ @person27 Good point, removed reference to magic. $\endgroup$ – Gnudiff Dec 4 '18 at 9:26

Fire, or maybe more opportunistically, water. Maybe ambush.

Presumably the invisibility doesn't extend to their housing. Look for the encampment of empty tents, village of empty huts, or whatever it is depending on your technological level, send in a bunch of soldiers in the middle of the night, and light up as much as you can.

Then either retreat before the smoke gives you away, or hang around and take advantage of the chaos to attack the 'holes running through the smoke and the spaces where water is pouring/shooting from.

Alternatively, if they're unwise enough to set up in a bad location geologically, dam a river and flood them out.

As for ambush, if you can figure out where they live, you wait until you can observe the effects of their actions. Well buckets dropping without anyone dropping them, unexplained disturbances at the riverside, farms tending themselves, livestock slaughtering itself. Then sneak up and swing a club or shoot an arrow where the person should be.

  • $\begingroup$ +1 for the "empty holes in the smoke" point - I was going to make a similar answer regarding fog. $\endgroup$ – Chronocidal Dec 2 '18 at 15:49
  • $\begingroup$ It's an interesting point. I wonder if you can actually see holes in fog. Wouldn't the rest of the fog get in the way? Also smoke would get in your eyes. $\endgroup$ – chasly from UK Dec 2 '18 at 22:21
  • $\begingroup$ Also attacking holes in fog would work for the other side too in close combat. $\endgroup$ – chasly from UK Dec 2 '18 at 22:23

It's an interesting premise. It almost seems like the answer would itself be the story.

As others have suggested, a big part of it would involve the factions attacking each others' settlements. They could besiege each other, loot and burn each others' buildings etc.; and they could use their invisibility as a tactical advantage. For instance, Arbol assassins could lie in wait under every Byrond bed, and just stab a sword through the mattress as soon as they feel someone lie down.

They could also use proxies, of course (since you specify that third parties can see both clans). Presumably there would be a bidding war to control the loyalty of any highwaymen operating in the area, for example. You might end up with a Cold War-like situation where the main combatants don't attack each other directly so much as they arm and fund different sides in everyone else's conflicts.

Over time, I guess that it would make sense for the Arbols and Byronds to abandon their own settlements – which would be subject to constant guerrilla warfare – and hide themselves in "neutral" towns. There are all sorts of interesting possibilities where they could be living side by side without knowing it, kind of like the situation in China Miéville's The City and the City.


I think he offensive power of invisibility greatly outweigh defensive power. In the field it is almost impossible to intercept mobile force so the fight will take place in settlements and other key locations. Now the attacking side can scout the surroundings and layout (but not defense) freely and simply chose the moment, place and force to attack. The defender have to be ready all the time.

With millennia of bloody warfare and now without ability to see the enemies (and enemy civilians) it could get ugly quite fast - there would no reason to show any restraint, sneak in with small force and

  • Poison the wells and spoil the food supply
  • Set something on fire
  • Apply weapons indiscriminately to beds and cradles

Now even if all attackers would get killed afterwards they usually inflict grave looses. And if attacking force is small then it have real chance to escape without retribution.

The defender have much more difficult task but can

  • Use dummies and misdirection - like having multiple chambers (or even settlements) - some used - some filled with traps - and switch them regularly
  • Try static defense - if they are able to limit approaches to very few round the clock monitored kill-zones they may have chance to get more favorable result. But the invisibility allows attacker to bring tools and helpers with impurity so I imagine anything short of underground bunker would allow the attackers to sneak around.

Finally I think one think could happen - after both sides settlements are savaged by unpunished foes both sides adapt nomadic lifestyle. With villages set up for night and torn down in the morning. That way the attackers would have to stumble upon settlement by chance and would have only very limited time to execute the attack. It would reduce intensity of the conflict and may with time turn the other side into invisible daemons from legends instead of real day to day threat.



As noted, actually killing people is hard work. Burning and stealing stuff is how you wipe a population out efficiently.

So you'll start out raiding. As each side is invisible to the other, you can do lots of theft and arson. If it extends to cards and mounts, it gets even worse.

This will do a lot of damage to both sides. Unaligned parties end up sweeping in and taking over territory destroyed by this invisible war.

In response, each side will seek to hide their settlements. They form hidden villages, and engage in warfare against their opponents. They'll test the limits of the "mercenaries" clauses (what if we don't pay them, but offer them plunder? What if we have no formal agreement, just a wink and a nod? What if we are their minions, and they pay us to be scouts for their army?)

Approaches to their settlements will be trapped in ways that reveal even invisible foes, while at the same time permitting defenders to move about undetected by attackers.

This situation either stabilizes, with both sides being secretive societies that hire themselves out as scouts to other powers, hoping to find where their foe is hiding. Or one is wiped out.

If one is wiped out, the other one's people are probably carried away as slaves. Their descendants spread over the world, each a blood-member of the clan. The surviving clan, now safe, may continue in its mercenary ways, banning out-marriage with prejudice. Over time the surviving intact clan finds that more and more of the regular world is incapable of seeing them.

They develop proxies, and work hard to spread the blood of their now-extinct foe. Those that remember the old clan are put to death, those that simply carry their blood are helped and encouraged to spread their seed. Every child they have is another nominal foe against whom these scouts are invisible.

One day they hope that every last human on Earth will not be able to see the Ninja-clan, and on that day they will be kings.

  • $\begingroup$ There's a slight problem with the last part of this. The clans (and their agents) are only invisible to the enemy clan (and their agents). Once one side has been wiped out, nobody will be invisible any more unless a few straggling agents continue to fight. They have no reason to because no one is paying them. Thus the spell of invisibility will disperse. The wizard has achieved his aim - although perhaps not as expected. $\endgroup$ – chasly from UK Dec 3 '18 at 20:13
  • $\begingroup$ @chaslyfromUK You create a "ghost" of the enemy clan and spread it. Is it carried in blood? If so, you start breeding slaves with enemy-clan blood and spreading their genes. Is it carried through some cultural thing? Work out how; get the last living representative of the clan to 'hire people and their descendants forever more' to 'brush their teeth at least once' in 'service of destroying your clan' to make many people technically members of the enemy clan or mercs. This is an awesome power; always, always seize control of any powerful curse and turn it into a weapon. $\endgroup$ – Yakk Dec 3 '18 at 20:15
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    $\begingroup$ I think what @chaslyfromUK is saying, is that the clan is a social construct, not a blood tie. The spell is placed on the idea and identity of the clans. Since it recognizes mercenaries, it would also recognize people who are married or adopted into the clan. -- Once one clan is defeated, all descendants will be released from the spell. $\endgroup$ – Ghedipunk Dec 4 '18 at 22:18
  • $\begingroup$ @ghed even better! Today piles of people identify with being celts, an ancient tribe. Debug what it takes to be a "member" then try to turn everyone you can into "members" of the enemy tribe. Even better if you can do it selectively without consent... $\endgroup$ – Yakk Dec 5 '18 at 4:02
  • $\begingroup$ @ Yakk - This has serious problems. Firstly, as I explained in the question, becoming a member of a clan is not easy. Part of it involves swearing a blood oath. If you get loads of people to join the opposing clan (How?) then you swell their numbers so the more there are the more outnumbered you are. Maybe better to get people to join your tribe. $\endgroup$ – chasly from UK Dec 6 '18 at 15:51

Attack engines akin to combine harvesters will happily mulch enemies - invisible or not. They have the benefit of taking out people, tents and other things above ground level without invoking a 'scorched Earth' effect on the land.

  • $\begingroup$ Not sure there were combine harvesters in medieval times! but it's an interesting idea! $\endgroup$ – chasly from UK Dec 5 '18 at 22:22
  • $\begingroup$ Naturally it wouldn't be sophisticated. All you'd need is a horizontal pole embedded with nails and blades, held at each end by two (well-defended) men. You just run across a battlefield with it. $\endgroup$ – DaveC426913 Dec 6 '18 at 15:35

I believe the described conflict/vendetta is more of an "I want to see you bleed and pay for your faction's crimes!" type of thing. So when they realize that they can't see the enemy "pay for it" and get satisfied, they could get this satisfaction by stealing the enemy's stuff (and mentioned above, "King of thieves" style), and/or sieging their villages/cities to the point of starvation, and/or using mass-destruction options compatible with their medieval tech (burning their places/things and hearing people scream in terror), but it probably is something that gives some feedback about the enemy suffering.

  • $\begingroup$ I agree. A very destructive and vindictive state of affairs. That's why the benevolent wizard wanted to provide a solution. $\endgroup$ – chasly from UK Dec 5 '18 at 22:21


The clans aren't invisible to new pets they've gotten after the wizard left right ? If they are this still works. Have dogs, crows, and other animals identify enemy clansmen. Then all the clansmen need to do is "disagree physically and energetically without safety in mind"; the clansmen just need to attack whatever the dogs identify.

This is pretty similar to how Law enforcement uses drug dogs. Just gotta get dogs to identify people you can't see. Should be easy enough given that you know where your enemies used to live.

  • $\begingroup$ Of course they will have dogs as well ;-) $\endgroup$ – chasly from UK Dec 6 '18 at 15:52

Duels are still possible, assuming both parties want to participate and make prior arrangements, probably via a third party. If they were in a small room or fenced enclosure like a boxing ring, they would still have to grope for each other, but contact would be frequent. It wouldn't be limited to one-on-one combat, either.

I once read about a ritual fight, between fictional native americans, in which they combatants' left wrists were tied together while they went at each other with knives. Again, it would require a third party and prior agreement, but mortal wounds would still be quite likely.

  • $\begingroup$ OP is asking about warfare, not duels. $\endgroup$ – L.Dutch Dec 3 '18 at 0:28

Negotiate peace among the tribes. A major change has occurred. Simply accept that major battle is not possible and attempt to make peace in accordance with the wizards wishes.
People not fighting and another plot arising is a great twist to a story. Especially if the original wizard could be found, or at least his journal. But in the meantime a greater evil emerges...

  • $\begingroup$ I believe the question was along the lines of "The wizard tried to stop them but, for the purposes of my story, it hasn't worked. Given this assumption how can I have my people still fight?" Unfortunately your answer doesn't provide a solution which fits in with how they wanted their story to go. $\endgroup$ – Lio Elbammalf Dec 2 '18 at 23:04
  • $\begingroup$ People not fighting is usually the most rational answer in any way, as for me, but do the OP's two clans act entirely rationally, or do they make rational steps to achieve irrational goals (such as vendetta)? $\endgroup$ – Cerberus Dec 3 '18 at 3:50
  • $\begingroup$ Good point. My point was to accept the futility of the quest. While it may take generations to accomplish, through acceptance: Truly hidden foes, are no foes at all. The only remaining point of conflict is resource management. Don't chop down trees across the border or risk being killed by the sound of your axe. $\endgroup$ – Strom Dec 3 '18 at 4:00
  • $\begingroup$ @Cerberus - If you read the third paragraph, second sentence of my question, you'll see that I mention 'vendattas'. ;-) $\endgroup$ – chasly from UK Dec 3 '18 at 14:07
  • $\begingroup$ @chaslyfromUK - and that's why I focused on this in my comment ;) $\endgroup$ – Cerberus Dec 4 '18 at 4:30

Okay but everyone seems to have forgotten the easiest answer: Hire someone to point out the enemies for you.

The clans are only invisible to eachother, so hiring an outsider will allow you to find the opposing clan easily. Plus you remain invisible so they will have a hard time defending. Most likely there will be a shift in fighting styles revolving around hired "spotters" who are linchpins in either sides offence. You can work several strategies around them, but the spotters are going to become the focus of the battles, either because they are pointing out enemies or being eliminated to cripple your opponents side.

Unless they count as mercenaries and get turned invisible? I was thinking of mercenaries being only direct combatants but spotters might count.

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    $\begingroup$ The question says: "They are only invisible to the opposing clan members or opposing mercenaries or opposing agents such as trained animals". So outsourcing won't work. $\endgroup$ – Philipp Dec 3 '18 at 13:56
  • $\begingroup$ @Philipp I'd say it depends. Let's assume we'd find an impartial outsider. He will answer truthfully to any clan member (of both clans!) what people he can observe around him. Would anyone turn invisble to his eyes? $\endgroup$ – Inarion Dec 3 '18 at 15:57

Trade War

Instead of physically attacking the opposite clan, both sides could switch to economical warfare. The members of both clans will likely engage in some form of economical activity in order to finance their standard of living and their war. So the clans could try to drive each other out of business in order to damn the other clan to a life in miserable poverty:

  • Steal their customers by offering the same products for a lower price. Even if it means you have to sell at a loss.
  • Drive their remaining customers away by slandering the other clan and their products.
  • Buy out their suppliers to deny them their raw materials. When the suppliers don't want to sell or you lack the capital to monopolize the whole supply, sabotage the suppliers.
  • Poach their best employees, even if you don't actually have anything for them to do.
  • Find out if they do anything illegal and rat them out to the legal authorities.
  • Steal their business secrets. If you find some secrets you can't use yourself, give them to anyone who can, just to harm them.
  • Force others to take sides. Do you have any business partners who depend on you? Tell them you won't make business with them anymore if they also make any form of business with the other clan.

The only downside: You always know that even if you ruin them completely, you won't ever have the gratification of seeing them beg for food.



Go to the enemy's camp and hold-on to your favorite position. Fire a paintball. Best shot is done with a shooting squad shooting at a wide angle, or few shooters with cluster paintballs. The paint will do its task even on the ground: each enemy troop stepping on it will leave footprints.

Even if the spell does not allow to see anything on their body (shield, arm, paint, etc) you have two tell-tale signs:

  • the path of the paintball is disrupted when it hits the target

  • the footsteps will once again be visible when they are left on the ground (enemy no longer carries it).

Now that the paintball has done its task, it's not time for laughing, it's time to pull your guns...


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