I'm planning for a Mouse Guard game that will culminate in the players facing down a bear!

The rules cover such scenarios far too briefly, only stating that you would need 20,000 mice to do so (via the War skill). This seems like far too few mice to wage war on a bear, also how would this even be done? Are the mice laying siege to the bear, or are they marching on it? Do you even use War? Could a single mouse climb the bear, insert itself into the ear, and assassinate the bear?

I realise that this is a task for the players to decide on but I want to prepare for the circumstances.

How do you kill a bear with mice? (and how can I prepare for this?)


5 Answers 5


Ooh, fun question. I'm having trouble even picturing 20,000 mice, but quick Googling lists the weight of a bear as 300 - 780 kg and the weight of a mouse as 16 - 27 grams, so to compare against a bear in terms of weight the mice would need numbers between 13,000 and 50,000. Frankly, even if this worked though, the number of casualties involved in such a fight would be such that I'd be rather disgusted with the mentality of the party who considered it a good idea. Maybe if they didn't know it was coming and that was their only option it might be reasonable, but that would require you to be writing your campaign using the Final Fantasy IX school of plot.

Assuming they can plan however, some kind of trap would be the approach I'd expect almost any party to take. Given the small stature of a mouse, their best bet would likely be to use nature and their environment against their enemy. The most obvious things that spring to mind would be knocking it off a cliff, dropping something heavy on it, or causing something else (a poisonous snake seems the most obvious choice) to attack it for them.

With that in mind, I don't think this really requires much prep work as a GM. The ball is very much in the players' court with this one; all you really need to do is try to spot any obvious flaws in whatever plan they go with as they come up with it, and make it fail if you don't think they've done a good enough job accounting for these flaws. If they're anything like most parties I've seen in such situations, they'll spend a whole session planning giving you plenty of time before the next session to think about how their plan will play out and where any weaknesses may lie.

  • 4
    \$\begingroup\$ Remember, the Scientist skill is used to make bear-traps! \$\endgroup\$
    – GMJoe
    May 9, 2012 at 6:10

A mouse can not kill a bear by force of arms. At least, not using Fighter nor Hunter. (See the size effect rules on page 223-225)

Animals that are two or more ranks higher than you on the scale may not be killed by your hand—not using Fighter or Hunter.

Use of Militarist requires more than 1 mouse. For a black bear, 6 steps up the scale, it's 20,000 mice. (p. 223, right col)

Use of Scientist is another matter... and while more accomplishable, is still likely to result in a dead mouse.

A bear cub, the smaller ones being equivalent size to a large racoon, requires only a few hundred mice...

So, a single mouse can, at best, be a nuisance.


There was a short story about the Guard dealing with a bear for 2010 Free Comic Book Day.

A discussion of mouse population sizes on the official Mouse Guard forums also discusses mice fighting bears.

Both of these sources imply that the Guard would not fight a bear in an open war (even if they could manange to muster 20,000 mice, which is doubtful following various ways of estimating the military strength of the territories and might constitute a campaign of its own), but that they would try to appease it or manipulate it to go elsewhere. This implies that other skills and conflict types, probably in combination, would play a role in the defeat of the bear.


Facing down a bear does not always require the players to kill the bear. Appeasing it, driving it off, blinding it (temporarily or permanently), feeding it, or frustrating it can all be accomplished without an army of 20k mice.


Frankly speaking, a bear is unlikely to expend the energy necessary to pursue a mouse unless there were no other options. The intake-to-output ratio for energy wouldn't be very good, assuming it was even positive to begin with. It's not inconceivable that the mice would need to deal with a bear in some manner but if you want a believable scenario you'll need a less direct threat; and less direct threats make non-combat solutions easier to identify and execute.

Some options:

  • Food has been scarce and a bear has been spotted foraging near one of the cities (maybe even Lockhaven).
  • A new bear has entered the territory and conflicts between it and other predators have been escalating, resulting in the destruction of several smaller settlements. The Guard must help the stream of refugees make it to safety.
  • \$\begingroup\$ But could a mouse kill a bear? \$\endgroup\$ Aug 15, 2017 at 6:30
  • \$\begingroup\$ @Pureferret My answer is a challenge to the nature of your question and thus is not intended to answer that question. A mouse should not be TRYING to kill a bear. It is an unreasonable activity for a mouse to attempt. A crab is practically a dragon, already. (See Legend of the Black Axe comics.) If you do not find it to be a useful answer, I won't take it personally if you downvote/don't choose it. \$\endgroup\$ Aug 17, 2017 at 10:13

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