violence in the media wrote:How much position, terrain, and tactical advantage would be necessary for said surly peasants to trounce a unit of ogres, trolls, or ghouls?
Like, do they need an extreme amount? A moderate amount? Are the monsters the side that need some sort of advantage to win that encounter? Does muddy ground matter equally to centaurs and earth elementals?
How big of an army do you need to fight a dragon? Can you fight dragons with armies? Can you fight a wizard with an army? What if you have an army and a wizard (or dragon) shows up and wants to fight it; what can you do?
Using 3E D&D as a base?
Ghouls aren't actually all of that scary of a threat to armies in battle. They're a nightmare to fight at low levels because a party getting overwhelmed with no relief is a real thing that can happen to you. But the paralysis doesn't last very long, their attack bonus is low, and the damage isn't really scary. The scary thing about ghouls, however, is the ghoul fever. But ghoul fever is again one of those things that is scarier to PCs than to cannon fodder.
Ogres are pretty scary. They can reduce a unit to paste every round and their AC not awful for their level. Concentrated ranged attack fire while a two or three-line shield wall takes the total defense action is probably the best way of dealing with these guys. You can also try to dogpile them with longspears and depending on how badass your militia is it might be for the best depending on how many ogres there are.
Trolls are fucking brutal. The biggest problem is the regeneration. The typical ways of dealing with regeneration are very, very hard to utilize in packed formation. Even if you do have that a troll can tear through a 1st-level or even 3rd-level militia shield wall like butter. Your only saving grace is that trolls have a pretty weak AC for their CR.
Assuming a goat pasture, mild weather, and no other special tactical considerations I'd say that it'd take 1st-level 450 melee militiamen (1st-level warriors) armed with large shields, scalemail, and spears/longspears and 150 ranged militiamen to take on 900 ghouls. The same number could probably take on about 100-150 ogres. The same number could probably take on 30 trolls if they had a way to deal with the regeneration,
A young adult dragon would fuck most armies up. Seriously, they have a frightful presence DC that you probably won't pass, endless breath weapon, they fly quickly, they have a high AC, and they also have DR. One red adult dragon could probably just swoop in and fry the ranged units, using its frightful presence to completely break the lines and then burn the units at will. The archers wouldn't even be able to get the dragon within two range increments before they start panicking and breaking their lines. I wouldn't be surprised if a young red adult dragon could take on 15,000 1st-level militia units without even suffering much damage. Smaug curbstomping Lonely Mountain over a lazy afternoon is actually pretty realistic given 3E D&D Dragons.
'Wizard' is just way too fucking broad. However, I will point out that a wizard with air walk/overland flight and a wand of fireballs is pretty much immune to any mundane army and could easily kill around 50 units per blast. If you're on a budget you could just planar bind a Hezrou and tell them to fuck people up with chaos hammer or unholy blight plus all of them damn dretches. If you're fighting orc armies or other chaotic evil creatures, get an astral deva instead.