Let's say there is an ethnic group of humans that live in an alternate Medieval Europe.

These guys developed the best immune systems on earth. They can't get sick from any disease.

The best part is a rich king wants a special army, an army that any enemy will think twice before attacking. Not by fear, but by repugnancy.

Since my army has 5000 troops of healthy, young, disease-proof warriors, my plan is to cover them in poison and the corpses of fallen enemies.

But not any poison — I want to use human feces, like the Romans did with garlic. That's the basic idea.

How can I maximise the advantages of my army? Let's focus on tactics and weapons only.

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    $\begingroup$ It's going to be hard to get this to work, disease isn't usually a ranged weapon, you're going to have to get close for it to work. And if you're already close, you might as well just stab people. $\endgroup$ Jun 5 '17 at 19:17
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    $\begingroup$ 5000 isn't very many. You're going to run low on manpower the first time you lay siege to a decent fortress. Your enemies will quickly learn to use standoff weapons...and fire...against your troops. $\endgroup$
    – user535733
    Jun 5 '17 at 19:49
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    $\begingroup$ Your best option is not to use them as an army. 5000 is a good number in medieval Europe, but steel-against-steel, they would not survive their first major encounter. Opponents will obliterate your force, succumbing to the diseases some time later. So you use your force as a threat, and only if you have to act, send out small groups of saboteurs to wreak havoc upon the enemy. $\endgroup$
    – Alexander
    Jun 5 '17 at 20:45
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    $\begingroup$ How about infection? Disease is the result of infection, but you can be infected without being diseased--I would guess they would be most effective if they were infected with everything. $\endgroup$ Jun 6 '17 at 1:23
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    $\begingroup$ "If they take the ship, they'll rape us to death, eat our flesh, and sew our skins into their clothing – and if we're very, very lucky, they'll do it in that order." $\endgroup$
    – Cort Ammon
    Jun 6 '17 at 4:12
  1. Our immune systems are already pretty good vs feces, given that our insides are loaded with feces. Generally being covered with feces means you are incontinent, which is not super fear-inducing.

  2. Mercenaries were already pretty repugnant in those days. Not so much their hygiene but the fact that they were loaded with syphilis because they raped everyone, and you are next.

  3. If you are going to cover them with the corpses of fallen enemies I propose they use small corpses or just select corpse parts - maybe the skin? The spleen? Corpses are heavy and they will slow your guys down. Plus if they are totally covered it will impair visibility.


If the point is to be repugnant, then you have to make them really sad looking and smelly. Covered in feces, rotting body parts, fungi and insects, gooh and ooze, will fulfill those two criteria (make the oozes really smelly).

The poison (disease) is another direction, making them dangerous: to touch, to inhale their air, to listen to their voice (breath), to have their weapons make wounds and spill blood, to even look at them (poison fumes to the eyes). And resistance to poison probably has nothing to do with the human immunity system, it's mostly against pathogenic microorganisms (diseases).

What weapons should they carry?
1. Very obvious ones (for terrorizing the opponents).
2. Far reaching and multiple target weapons (for quick spreading the disease plus maximum psychologic effect).
3. Quick reloading, easy to make, carry and imbue disease ammo.
* I am not aware of any weapon that fulfills all of the above, but I'm sure anything can be invented when sufficient resources and engineer skills are available.
4. Light armor (if any) for quick movement, shields for protection from ranged attacks, spears for protection from cavalry charges, shortswords for melee.

What tactics should they employ?
I visualize them as a fast moving and flexible formation, like light infantry or javelineers, their main weapon being RANGED. They should have some capabilities to survive initial charges by cavalry and heavy infantry. Or maybe the rest of the army should protect them from them. After that, they should employ their psychological weapon to make them run away, but at the same time disperse to allow the use of their ranged weapons against any offenders.
Their biggest vulnerability will be enemy ranged weapons, which is why they should be very quick on their feet (no horses, the poor animals will be dying from the diseases very easily) and have some kind of shields.
Attack: go forward and disperse (probably under cover of rest of the army), rain disease to the enemy, fall back under cover, then join the fray at the SIDES (away from own troops!) for maximum psychological effect.


Believe it or not some of this was actually done in real life. See: https://en.m.wikipedia.org/wiki/History_of_biological_warfare#Antiquity

The first thing that came to mind when reading the question was the corpse catapult. It was a tactic used when laying siege to castles. Plague victims, corpses, and sometimes even excrement were flung over castle walls in the hope of spreading disease and weakening the moral of the defenders.

There's also a long gross tradition of dipping blades and arrowheads in filth and poison in the hope of turning a flesh wound into a fatal wound.

Overall I'm thinking that making your army smell like death and filth won't be all that effective though... Armies would have smelled pretty awful back then regardless. March 5000 men and draft animals for a few miles and everyone's​ going to smell like feces without extra efforts...

But many tribes and armies did go out of their way to "look scary" using mutalted corpses, bones and so on. There may be some psychological advantages in doing this, but it has also been known to backfire and get them labeled as barbarians, savages, and more recently as war criminals.


If You are after psychological effectiveness I think You should make Your "mercenaries" not fight at all (if possible).

Make them a sort of Death Phantoms that move at night and use their resistance to disease to spread it.

A sword (not to speak about arrows) will always be faster than bacteria and very often it will be faster even of nerve gas.

Spreading terror is what You are after.

Make Your agents mysterious by wrapping them in black rags concealing something able to stop arrows and arm them with some way to spread infection (and some chemical mustard gas flask).

You can booby trap them so they will never be caught alive and, instead explode killing whoever is in proximity (chemical warfare maybe useful here).

Make them move as stealthy as possible, while making plain that coming near to them is certain death; even if you manage to kill some or all of them that won't save you.

For personal weapons, used only when cornered, favor concealed armor and long knifes for short distance and mustard/smoke bombs to avoid fight if still possible.


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