In combat, do creatures have complete knowledge of the locations of all other non-Hidden creatures in the combat?

Question

In my question about Hiding I realised in the comments that I was resting on the following assumption:

In combat, every creature knows exactly (to the square) where every other creature in the combat that isn't Hidden from them is.

Here "Hidden from them" means "have taken the Hide action and succeeded against their passive Perception".

Notably then, "Hidden from them" does not mean "unseen (e.g. behind a wall), but hasn't taken the Hide action"

I wasn't able to easily identify from the Stealth and Hiding rules why I thought that, but I'm pretty sure it does come from the rules somewhere.

Is this assumption correct? If so, what rules make it so?

Answer 1

TLDR: Yes, you can always pinpoint someone's location as long as they're not actively hiding

This is an amalgamation of a few rules that, when taken together, end up with the conclusion that everyone in combat knows exactly where everyone else is.

First, this is what happens when you try to attack a creature that you can't see (SRD p. 94, "Unseen Attackers and Targets"):

When you attack a target that you can’t see, you have disadvantage on the attack roll. This is true whether you’re guessing the target’s location or you’re targeting a creature you can hear but not see.

Backtracking a bit, think about how ranged attacks in 5e work. Archers simply need to see their target and they can attack normally. If an archer is deafened, they can still target a baddie 50 yards away without penalty. The only thing the 'deafened' condition applies is (SRD p. 192, "Deafened"):

A deafened creature can’t hear and automatically fails any ability check that requires hearing.

So the only thing necessary for an archer to attack an enemy is that they can see the enemy. Seeing them allows them to know where the creature is to the square, allowing them to make their attack without disadvantage. Archers also don't have to worry about sporadically missing their shots because they picked the wrong square to attack, so we know that seeing an enemy is all that is required to know their square.

Now let's apply that to the SRD passage. If the creature you're attacking doesn't know where you are, you automatically get advantage against them. However, getting advantage (without hiding) by not having a creature know where you are is relatively rare in combat. Thus, if most creatures in combat did not know where the other ones are by default, then most attacks would be made with advantage, which clearly doesn't happen. The only way to have combat proceed normally (where most attacks don't get advantage due to being unseen) would be that every creature has a good visual awareness of the other creatures without having to do anything special to achieve it. Couple this with our above archer example where we were able to infer that visual awareness is sufficient to know the location of a creature, and you get the first part of the argument which is 'creatures in combat see all other non-hiding creatures in combat'.

So we now know that in combat, the rules expect that everyone sees everyone else. What about positioning and direction? This is covered also in the SRD pages 80-81 ("Hiding" sidebar):

In combat, most creatures stay alert for signs of danger all around, so if you come out of hiding and approach a creature, it usually sees you.

Again, we see that most creatures are aware of their 360* surroundings in combat, and even approaching from behind or the sides is not enough to evade their detection. The only way for this to be possible would be for the creature to know where you are, because as we saw earlier, not knowing where a creature is means that the creature automatically has advantage on you, which does not happen in this case.

Finally, what if the target is behind a wall and completely unable to be seen, but is not hiding? The rules have a section for that as well under 'total cover' (Basic Rules p. 74, "Total Cover"):

A target with total cover can’t be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. A target has total cover if it is completely concealed by an obstacle.

So in this case, since the target is not hiding, we cannot see them but we can hear them. This goes back to the Unseen Attackers rule (SRD p. 94, "Unseen Attackers and Targets"):

When you attack a target that you can’t see, you have disadvantage on the attack roll. This is true whether you’re guessing the target’s location or you’re targeting a creature you can hear but not see

So if we cannot see a creature but we can hear them, we can attack them with disadvantage. Since attacks where we cannot pinpoint the location of the creature automatically fail, we know that hearing the creature is enough to pinpoint their exact location.

So putting all this together, we see that a creature in combat can see every other creature in combat as long as they're not hiding (otherwise pretty much everyone would attack with advantage every turn), seeing someone is all that's necessary to attack them normally (otherwise ranged attacks would be impossible or always made at disadvantage, and being deafened would affect ranged effectiveness), hearing but not seeing someone still allows you to pinpoint their location (otherwise total concealment would make it impossible to attack someone and not just impose disadvantage), and attacking a creature without disadvantage or potentially automatically missing means you must know their exact location (otherwise you would trigger the 'Attacking unseen targets' rule and miss by default). So because the situations in parentheses above don't actually happen, we know that all creatures know the exact location of all other creatures unless one of them is hiding.

Answer 2

It is mostly up to the DM

Other answers (see Percival's answer, for example) already make a good job analyzing the rules that are written.

I am basing this answer on a podcast with Jeremy Crawford where he talks about stealth in an attempt to clarify the interpretation of those rules.

(Disclaimer: these transcriptions are done by me so they might not be 100% accurate)

At around 28:30, Jeremy Crawford describes that under certain circumstances the location of a combatant might not be known depending even without hiding:

Now in some cases a DM will decide that even an invisible person's location is unknown to combatants, because this goes back to what we were saying before of the environment and character's attentiveness. It's really up to the DM. The DM might decide that, alright that wizard that cast invisibility on herself, the orcs... they've lost track of where she is even though she never bothered to hide.

He then moves on to describe some environmental circumstances that could distract combatants and allow this situation to happen.

However, he does also mention later that invisibility never being enough to hide is a perfectly valid interpretation as well, at around 29:33:

But we assume that it's also perfectly in keeping with the rules for a group to assume that unless a person hides people generally know where invisible people are in combat because of just their movements you know their sword swings, they're seeing the effect in the environment

And at around 32:50:

Let's say a group wants to just sort of run the rules as barebones as possible with as little DM interpretation as possible on stealth. A group is going to be on really firm ground if they just decide: oh we just assume combatants always know where invisible characters are unless those characters have hidden themselves you know by making a dexterity (stealth) check

This is all more focused on invisibility and your question is even more generic but having listened to the whole thing, the main idea that is conveyed is that hiding means being both unseen and unheard and that it is acceptable for a DM to determine that circumnstances that render someone unable to be seen or heard grant them the benefits of hiding, even without taking the Hide action.

On the origin of this idea

The idea of the rule as you place it may have originated due to the 4th Edition's Rules Of Hidden Club which include:

The First Premise: Everyone knows where everyone else is, at all times, period.

The status "Hidden", achievable only through rolling Stealth, is the only exception to this.

5th Edition intentionally does not have rules such strict rules on stealth (also mentioned in the podcast, really go listen to it!) and this is left to the DM's common sense.

Answer 3

The best I could find was the following from "Unseen Attackers and Targets", PHB pg. 194:

When you attack a target that you can’t see, you have disadvantage on the attack roll. This is true whether you’re guessing the target’s location or you’re targeting a creature you can hear but not see. If the target isn’t in the location you targeted, you automatically miss, but the DM typically just says that the attack missed, not whether you guessed the target’s location correctly. When a creature can’t see you, you have advantage on attack rolls against it.

If you are hidden—both unseen and unheard—when you make an attack, you give away your location when the attack hits or misses.

This implies that a non-hidden creature can still be tracked, but since it talks about guessing the location, I'm not sure if this means you can perfectly track the location or whether you can just guess (i.e. the DM says "the invisible enemy goes towards the door" so you know roughly where they are relative to your surroundings but not to the square, as you put it).

So, my conclusion is that you do not know where they are to the square, but they'd need to Hide for you to not know where they are at all.

Answer 4

You know the location of anything you detect

Mechanically all senses come under the Perception ability, which is fundamentally about "spotting, hearing, or otherwise detecting the presence" of something. Whether you can see something, hear it, detect it with truesight, or tremorsense, you know where it is.

Not all senses are equal

On top of that, all senses then provide sense-specific information. If you look at someone, you can see the color of their clothes. If you hear them talk, you can tell the pitch of their voice. If you look at them with truesight, you can detect their true form and any illusions. If you are sensing them with tremorsense, perhaps you can sense if they are fidgeting or uncomfortable.

However just because any sense can detect things, doesn't mean they are all equal. Seeing has many mechanical advantages over other senses, codified in various rules. For example in the Unseen Attackers and Targets section:

When you attack a target that you can't see, you have disadvantage on the attack roll.

...

When a creature can't see you, you have advantage on attack rolls against it.

Answer 5

There are no general rules for knowing a creature's location.

The Hiding rules say "you give away your position if you make noise", and the Unseen Attackers and Targets rules also say "when you make an attack, you give away your location when the attack hits or misses."

But if you just pick any two creatures A and B, there are no rules telling whether A knows where B is. In particular:

• The rules for the Stealth skill and the Hide action don't say that anyone doesn't know your location when you're hiding.
• Nor do they say that a creature that beats your Stealth check with a Perception check learns your location. No effects from passing that check are mentioned at all, in fact.
• The Unseen Attackers and Targets rules say that you can guess a target's location but not under what circumstances you'd do that (other than if you can hear but not see them).
• They say "if you are hidden--both unseen and unheard ... you give away your location" but the Hiding rules don't say you become hidden. They do imply that you are unseen and unheard, but that's presented as a precondition to hiding: you can't hide while being seen, and you give away your position when you make noise.
• The Hiding rules contain this sentence: "In combat, most creatures stay alert for signs of danger all around, so if you come out of hiding and approach a creature, it usually sees you." However, the key words there are approach and see: if you enter a creature's line of sight then it knows where you are because it can see you.
• The Blinded condition (which is also used to define the effects of heavily obscured vision and invisibility) says "You can't see." It makes no mention of not knowing where other creatures are.

In short, stop trying to apply the 4e "Hidden club" logic. There is not a mechanically defined "Hidden status" that flips the switch between "everyone knows your location" and "no one knows your location". Creatures know your location if they have a reason to know your location, such as being able to see or hear you, or remembering where you are. This is very fuzzy and situational and that's why the rules around stealth have the caveat that this is all at the DM's discretion.