# What kind of a unit/army would prefer fighting from a low ground position?

It's a well-known fact that attacking or defending from a high ground gives a wide range of advantages over an opponent occupying a lower position.

I'm DM-ing a campaign where PCs are about to defend their freshly acquired castle and the village around it from a group of invaders. The village is surrounded by small hills, which obviously leaves them in pretty bad position. I want to create a group of very specific units, excelling at fighting from low ground, so the PC task is going to be to get their help.

I know that it'd probably better to set some defenses on the hills and catch the attackers off guard, but what type of unit would be more effective fighting from a low ground, against an enemy shooting and rushing down the hill? What kind of equipment or abilities would it have? Should it be of a specific race? There are no firearms but dwarven engineers exist and they may help with some unconventional gear. The world setting is fantasy, so magic is acceptable to a small degree but very rare.

I'm looking for a kind of unit that given an opportunity to pick their position during the battle, would always prefer to be on the low ground to be the most effective.

• Are you bound to humanoids? – L.Dutch Sep 14 '18 at 12:48
• I was thinking of an army of snake like being with constricting ability... something along clash of the anacondas... – L.Dutch Sep 14 '18 at 13:37
• The problem with sappers is that you never have an army of sappers. The only valid answer to "What kind of a unit/army would prefer fighting from a low ground position?" is "No kind. – RonJohn Sep 14 '18 at 14:14
• Anakin Skywalker – Captain Man Sep 14 '18 at 16:39
• A dead unit, or one with a death wish. – jpmc26 Sep 15 '18 at 0:54

The high ground is better because...

• you can more easily throw stuff onto the enemy,
• you can walk down saving strength,
• you can see further, and
• in close quarters you stand taller.

We need to demolish those bonuses for the attackers, and the accompanying mali for the defenders.

Some points (seeing,walking) are already weakend, because the battle site is known, and the defenders do not need to move much anyways.

If there was a race of warriors that near perfect natural cover from above, the rest of the main points (throwing, taller) would be weakened. The problem with super-armor is that it encumbers a lot: but this is a plus, it explains why this race is not always winning - they can' t move so well. So now we have warriors formed like mushrooms.

They need some martial ability, which either should not require line of sight (say a poisonous gas or spores that is slightly lighter than air) or the armor needs to be transparent (otherwise they have to peek around it, exposing themselves to enemy action). So now we have warrior-mushrooms with poisonous spores and (possibly) a clear-crystal shield-head.

If we go with the transparent armor above, we need a way to exploit it: line of sight magic, lasers, basilisk stare, or, my favorite: telepathic links to powerful but dumb-as-bricks airborne creatures. Say, sacks of lifting gas with incendiary bomblets. The mushroom-warriors look up the hillside to the approaching enemy (through their impregnable crystal shield) and compel their floating thralls to release their searing cargo at the right time.

So a race of crystal-mushroom warriors with floating, poisonous spores and balloon-bomber thralls. They like getting paid in nitrogen-rich biomass, btw., especially from bovine sources.

• Hahaha that made me laugh out loudly a few times but it answers the question quite accurately :D Love the idea of mushroom warriors, great job @bukwyrm! – LordMarkus Sep 14 '18 at 15:15
• Soo… A scorpion turtle? Sounds like it could exist in the Avatar universe. – Fabian Röling Sep 15 '18 at 0:20
• "you can more easily throw stuff onto the enemy," You can also throw it with more momentum, since the trajectory doesn't oppose the gravitational field. – jpmc26 Sep 15 '18 at 0:57
• “say a poisonous gas or spores that is slightly lighter than air” did you mean slightly heavier than air? If it pools in the depression the mushroom-warriors are fighting from it would be advantageous. Of course the warriors themselves have to be immune. – Michael Sep 15 '18 at 9:34
• OK, but what if the attackers have a unit of jumping Italian plumbers with big mallets and a penchant for smashing mushrooms? – RBarryYoung Sep 15 '18 at 21:36

# An army that moves in the ground

Human warfare has actually been conducted under ground. From the cave bases in Afghanistan, to tunnel warfare in Vietnam, to mining in The Great War.

In a fantasy world, where some races live under ground, like for example Drow and Duergar, relying solely on being on a hill to be safe against attackers would be folly at best.

With the victi... eh... defenders, conveniently placing themselves on a hill — with luck a soft earth hill instead of a solid stone hill — undermining their pathetic fortification will be a breeze. Dig out tunnels under the walls and major buildings... blow out the support structures for the tunnels... and watch the whole thing come crumbling down.

• It takes some time to undermine defenses like that but it works just fine ;) Thanks for your answer! – LordMarkus Sep 14 '18 at 13:12
• Battle is done from below!! – Joe Bloggs Sep 15 '18 at 11:37

Mud Hoses

Dwarven engineers create some kind of very big and powerful water/mud hoses. As soon as attackers are charging downhill, they target the hoses against the hillside, to generate a very slippery terrain. You can add spiked traps below or a an elite group of spearmen to deal with the rolling attackers.

• Hey this is quite creative to turn their charge into uncontrollable fall ;) Thank you very much for the idea! – LordMarkus Sep 14 '18 at 13:06
• The problem is that the mud then slides down onto your castle. – RonJohn Sep 14 '18 at 14:09
• @MatthewRead mud slides wipe your town away. – RonJohn Sep 14 '18 at 19:09
• Oh definitely, but I don't think it would take that much mud just to make the hills slippery. – Matthew Read Sep 14 '18 at 21:56
• @RonJohn, it doesn't say the mud slides. It says the attackers slide down the mud. Haven't you ever played outside in the mud? ;) – Tracy Cramer Sep 14 '18 at 23:21

Not necessarily a combat unit: Sappers.

These are the guys who make castle defenders very nervous, just due to the possibility of being there. Now, we do not attack a castle, but defending a valley against an enemy who will be comming down a hillside... How about we treat the hillside like a castle wall, and bring it down when the enemy charges over it? Alot of traps on the way, cave-ins under the feet of the enemy, and you will demoralise your opponents troops! They will not know "Is the path ahead prepared or not?" and slow down by a fair amount.
Given enough preparation time, sappers could be the terror on the battlefield.

• What army prefers the low ground? The one that's already booby-trapped the high – Chromane Sep 14 '18 at 13:02
• I completely forgot about the sapers! This is very helpful and the defenders are aware of the upcoming attack so they'd have some time to prepare. Thank you :) – LordMarkus Sep 14 '18 at 13:11
• Yep, sappers. But they just dig a trench, fill it with water, and go home. There's no high or low ground; there's just two sides of what's now a river. – Mazura Sep 14 '18 at 16:14
• I intended to upvote this answer and unintentonally downvoted instead. I can't fx this. Sorry. – Walter Mitty Sep 15 '18 at 22:02
• @WalterMitty You can change votes if the answer is edited (hint hint) – Bob Sep 17 '18 at 2:03

In the real world, this is known as a reverse slope defense.

As noted in the Wikipedia article I cite, this is most commonly used by units to reduce the effectiveness of enemy long range or indirect fire, or to set up a sort of ambush on enemy units when they crest the hill.

when enemy forces are known to have superior long-range direct-fire or indirect-fire weapons, the majority of the defending force can use the hill to limit enemy observation and reduce the effectiveness of said long-range enemy fire. This tactic may even succeed in deceiving the enemy as to the true location and organisation of the main defensive positions. Typically, a smaller unit is still posted on the forward slope to perform observation and delay attackers if the defending force needs to relocate its main body onto the forward slope. Otherwise, when the attacker advances and passes over the top of the hill, they may be ambushed by short-range fire from the defender on the reverse slope

Notably, this is only effective for ranged units - you wouldn't see a melee unit setup a reverse slope defense, as being downhill puts melee units at a significant disadvantage. Ranged units can use it great effect in a great many situations, but it's not a tactic that generally applies to one specific type of unit or another; it's a situational tactic. If your opposition outranges you, (say you have a unit of shortbows facing off against longbows, for example) or you're concerned about indirect fire (your opponent has a lot of siege weapons and mages throwing fireballs around), or can't find another way to get an advantage, setting up a reverse slope defense and baiting your opponent into an ambush as they crest the hill might be a good idea.

• I've never heard about it but that's a really good idea! Reverse slope defense with short range fire sounds great! – LordMarkus Sep 14 '18 at 14:36
• The problem with your answer -- unless the question has been radically changed since I last read it -- is that you're still on the hill, and the question talks about the castle being at the foot of the hill. – RonJohn Sep 14 '18 at 19:06
• @LordMarkus no, that's not how the RSD works. It's specifically for (EDIT for clarity: defending against) "superior long-range ... weapons". – RonJohn Sep 14 '18 at 19:08
• @RonJohn Not usually, no. A reverse slope defense is typically done at the base of the hill, not on the slope. Makes it easier to entrench. Or assume a firing position (crouched or prone, in the case a reverse slope defense, prone is the way to go that gives the attackers on the crest of the hill less of a target to shoot back at). – HopelessN00b Sep 14 '18 at 19:09
• @RonJohn No, you read that wrong. Reverse Slope defense is used by the side with inferior ranged armaments. They use the hill to block the superior range or and observation/indirect fire capabilities of the other side. Once the guys with the better long range weapons crest the hill, they're in range of your weapons, and you've neutralized their advantage (and usually put them at a disadvantage, as counter-intuitive as it sounds). – HopelessN00b Sep 14 '18 at 19:11

If your army was say 80% archers, and the enemy was mainly not, and the low ground can be flooded to make it marshy, you'd love to stage the battle on that low ground. While the enemy is out in the open slowly trudging through the muck trying to get to you, your forces are filling them full of arrows. Anyone heavily-armored enough to have any hope of survival out in the open against massed archers is liable to have extra problems trudging through the mud (and God help those who slip and fall down in it). Once those melee fighters do manage to get to your forces, they're going to be exhausted.

If the other side does have some archers, a good trick would be very early on have everyone pack up their bowstrings, then have a druid or mage cause a sudden downpour. That will slacken the enemy bows, making them much less effective than yours.

This was the basic setting of the crushing English victories at Agincourt and Crecy.

Don't get me wrong, your archers would probably still also love to be standing up on a nice hill. However, this is a way to get the benefits of a hill, but have it on nice flat ground that cocky knights will be willing to assault you from.

• For bonus points, make sure to show those knights that your bow-plucking finger is ready for them. – T.E.D. Sep 14 '18 at 15:24
• "This was the basic setting of the crushing English victories at Agincourt and Crecy." You mean, having druids and mage cause a downpour? :D Seriously though, this is an excellent answer, it really takes advantage of lower ground. – Frax Sep 15 '18 at 14:28
• @Frax - The downpour bit happened at Crecy. I do not have any information about what kind of magic was used to invoke it. :-) – T.E.D. Sep 16 '18 at 4:59
• Yep, I was going to suggest mud! – Matt Bowyer Sep 17 '18 at 20:49
• @MattBowyer - Going from your name, I'm guessing you had archery in mind as well. – T.E.D. Sep 17 '18 at 20:59

The army of... the navy.

• If something is higher than the sea level, it's going to become target of more cannons/arrows, and probably WAY lighter than the sea level farer.
• On the same level (sea) it'd be level play (heh... ok.)
• The lower you are, the easier it's for you to spot the ones above and the harder you are to be found by them.

And buoyancy is relatively easy to control (more than gravity, at least). So munitions/attackers won't have a hard time coming hard from below. Like submerged (spiky/explosive) inflatables hitting their faces hits usually stronger than the same mass being pulled by just gravity.

So the sea village will look almost normal, but the sea castle should have more guards and higher (lower?) walls on the way down than the way up. Or even better, be all the way down. The sea hills that surround the castle will be no problem. They are called waves, and they will move themselves out of the way, leaving the attacking army surprised and lost because the advantage is gone and the castle just disappeared behind a moving hill. Unless the attackers are surfers, but they are too light armed to pose a challenge to sturdy castle walls, and too cool to bother carrying scuba equipment to even touch the castle if its at the bottom.

May be fun.

• That's unconventional but very interesting look on the matter. I like the idea of moving hills being a part of a defense system:-) – LordMarkus Sep 14 '18 at 14:39

In a conventional force on force scenario, even combat engineers will have a great deal of difficulty (saps and tunnels can be bombarded from above to collapse them, for example).

So don't fight a conventional battle, but rather go 4GW on the enemy:

Fourth-generation warfare (4GW) uses all available networks -- political, economic, social, and military -- to convince the enemy’s political decision makers that their strategic goals are either unachievable or too costly for the perceived benefit. It is an evolved form of insurgency. Still rooted in the fundamental precept that superior political will, when properly employed, can defeat greater economic and military power, 4GW makes use of society’s networks to carry on its fight. Unlike previous generations of warfare, it does not attempt to win by defeating the enemy’s military forces. Instead, via the networks, it directly attacks the minds of enemy decision makers to destroy the enemy’s political will. Fourth-generation wars are lengthy -- measured in decades rather than months or years.

So the attackers sweep down from the hills and find....nothing. The knights and men at arms have fled, leaving only a confused and frightened peasantry. Rumours abound, but when questioned, the peasants have no usable information, only a mass of contradictory stories, many of which sound like nonsense. Unsatisfied, but seeing no real threat, the attackers move into the castle.

Men start disappearing at night. Horses are stolen. Raiders come to steal cows and burn crops. Trade caravans are robbed just outside the edge of the territory. Small treasures disappear from the castle (or are sometimes found in entirely different locations from where they were stored). The peasants are in an uproar, and try to crowd into the castle at night for protection. Yet, no matter how rapidly the new lords move, or if they send forces out to piquet the area, they never seem to find anyone. It is as if the night raiders have inside information, or hundreds of eyes watching their every move.

The new lords may suspect the peasants may have something to do with this, or the former owners are hidden in the population somehow, but face a quandary: torturing or abusing the peasants for information will only turn them against you, but right now they are already mistrusting the new lords because there is no protection from the night raiders. It is lose/lose either way.

Eventually, the new lords will be holed up in the castle, as if they are under siege. The food supplies are running low, morale is shot and lack of water and disease start to take their toll. At this point, your forces can come out of hiding and triumphal reappear to "save" the peasants and finish the siege. After all, the new lords are trapped in the low ground.....

• This probably won't work, because the peasants will be abused by both the old and the new lord, and don't give a crap about either. – Erik Sep 15 '18 at 9:25
• I doubt this actually answers the OP's question as intended, but +1 for this unconventional take on the problem. – Palarran Sep 15 '18 at 15:04

About the only thing I could think of that might be more effective from low ground would be a shield/spear wall. The shields would be at a better angle to provide more protection from arrows and it would be harder to stop a downhill charge that is met with the spears.

The only benefit that they have is that they are defending from a downhill position and not attacking from one.

• If you make the shields highly reflective, and the angle is steeped enough, during the day, this shield wall would also serve to blind the attackers (though the attackers will also somewhat have the sun to their back as well. Though if the defenders have sun glasses, this can act as a solar trap.) – Tezra Sep 17 '18 at 18:19

Carbon monoxide / carbon dioxide poisoners

Carbon monoxide poisoning is documented as occurring as far back as 200BC. Carbon dioxide poisoning killed 1746 people and thousands of livestock in one naturally caused incident in 1986 at Lake Nyos. In some incidents of volcanic activity it has not been clear which of these gases or others caused the fatalities. It can only happen in enclosed spaces or low-lying depressions with minimal air currents, so this is not a defence that can be used on high ground. The danger with these gases is that people often do not realise they are being poisoned until they are too debilitated to remove themselves from the affected area. Dwarven miners can be expected to have learnt about these hazards from their experience underground - mining was the area that high numbers of fatalities inspired research into the causes.

So - I propose a small heavily armoured force that:

• do not need to breathe (constructs or undead if available) or
• that can hold their breath for hours at a time (if there is a race with that ability) or
• that have magic / air bottles that will let them breathe normally.

Make them obviously equipped with missile weapons only and have them build fortifications that provide cover from missile fire but will not significantly impede a charging army. Evacuate all of the villagers and livestock, then flood the area with CO or CO2 as available.

The attacking commander will see a ranged combat opponent with no significant melee capability. Unless he knows the trick, it looks like he is better off charging into close range than undertaking a prolonged archery / siege weapon duel. Once the attacking forces charge in, the defenders just need to fall back before them and all of the attackers will be dead in a few minutes.

The possible weakness of this plan in your campaign is the low magic setting. In order for this to be a feasible defence, the defenders must be able to operate in a poisonous gas environment, which requires advanced "dwarven" technology or a racial / magic solution.

Any army that is facing an attack from the air will likely prefer to fight from ravines and valleys because it will necessarily force their foe to fight on more predictable terms (ie: limited lines of attack)

On the other hand, ravines and valleys channel the bomb-blasts and reduce mobility on the part of the defenders, but any fortification that can withstand such weaponry is equally able to do so in the valley/ravine as it is on top of a mountain.
So build it low in a place where lines of attack are few and your defences can be properly oriented against the foe.

# Wildfire!

You have a dense forest on the slopes.

You can light a fire in the crowns of the trees. These fires are extremely fast moving, and more so on a slope. A tree fire in a flat area can be growing faster than a human, literally running for his life, can flee. Yes, that actually happens.

The fire is extreme when it reaches the top of the hill. Like "you can not imagine" extreme. No really, you cant.

The direction of the strongest blast can change very quickly - if you can control the wind, even a little bit, you have much control for the fire.

Now, you want multiple shots! The wood can be separated in independent parts - burning separately. By nature - after landslides, burrowing all trees, or just a part of the hill where no plants can grow - blank rock. It can be man made, like for large high voltage power lines - the company takes very much care that the plants come not near the high voltage lines. Or simply fire breaks - spaces, held free of plants to have fires not cross it.

You can have only one shot per section, or sometimes two. But they are strong. Nobody can survive, even with some shelter. The oxygen runs out.

So, make sure you light the top of the trees, and good luck!

• Good idea but can not be used many times. – KalleMP Sep 18 '18 at 12:45

Troops that are good in trench warfare.

Troops that have past successful experience of fighting in trenches when under dire situation will naturally gravitate towards digging-in.

Such troops would prefer to conserve energy - as a tactic or out of necessity (low in resources) - by seldom attacking enemy. They would prefer enemy to come to them.

Being on low ground can be a clever technique of luring enemy to attack them.

In order to cut losses from their enemy's missile weapons before the attack they may place their trenches as far away from their enemy's (elevated) position as they can, and/or place some makeshift low wall from whatever is taken out of ground when the trenches were being made.

Core tactic of such troops is to convince their enemy that they are at a disadvantage and so is easy to take out, AND cannot be taken out just by throwing missile weapons on them.

• When Austroungarians and Italian fought on the Alps during WWI they were using trenches and they were putting a lot of effort in staying in the high ground. – L.Dutch Sep 14 '18 at 20:24
• @L.Dutch Troops in WWI werent for the most part trying to lure their enemy to attack them, instead they were looking for opportunities to attack, hence preference for high ground. Some other troops may have a different tactic. – Atif Sep 14 '18 at 20:38

What about an army that specialises in using lighter than air toxins? Or fire? Since these toxins would travel uphill easier than downhill, it would make sense for them to prefer fighting from low ground positions.

• Lighter-than-air toxins would usually go straight up instead of along the surface of the hill. Fire might work, if prepared right. – Paŭlo Ebermann Sep 16 '18 at 21:10
• @PaŭloEbermann if the toxins are just lighter than air, it would take them a while. If the toxins almost weigh the same as air, they would get blown by the breeze towards a target than go straight up. – VenusUberAlles Sep 25 '18 at 10:38

## You need dwarves from the Giantslayer Clan

While these warriors don't necessarily prefer the low ground, they are extremely well-trained in overcoming the disadvantages. They are heavily armored, sure-footed on rough ground, used to attacks from above and their shield wall seems like a cliff-side. No human army can match what the giants throw at them (literally and figuratively).

Along with their elite soldiers come the engineers. They specialize in turning the battlefield against the enemy. Traps to hinder movement, smokescreens to limit visibility and effectiveness of ranged weapons and when battle is joined they use flamethrowers to repel cavalry charges.

If you're exceptionally lucky, they will be accompanied by a Stormcaller. Hilltops are not a good place to be when the lightning comes and arrows are all but useless when the winds are tearing at you.

• Stormcaller is very creative ;) Thank you for the idea, I may use it to turn the sides of the battle. He is definitely the one who wants his enemies to be high on top of the hills ;) – LordMarkus Sep 15 '18 at 13:57

## A Big Boat

The reason you would prefer a low-ground position is that low ground is also where the water is, and if you have a large boat with lots of guns, you want to be able to use it.

Especially if it's a smaller town, it might not have a lot of its own firepower, but a warship sailed in on the river from a nearby coast could add it's own powerful arsenal. Maybe its a pirate ship hiding inland temporarily, or a warship that needed to resupply unexpectedly. Either way, getting it on the side of your PCs would provide cannons and an excellent spot to defend from.

• Warship stationing on the river and firing all his canons at the enemies rushing down the hill sounds epic! Good idea :) – LordMarkus Sep 15 '18 at 13:58

Creatures that have upward angled eyes would prefer to fight from below because they can see better looking up. If their heads were unable to articulate in the downward direction it would drive their evolution towards 'looking up' and create features essential for defending themselves from higher threats.

Cavalry.

Hills aren't easy to plough and are therefore often wooded ... or steep and rocky.

Cavalry (especially a formation or unit of cavalry) may prefer flat open ground (e.g. river valley, flood plain, flat fields, roads, etc.).

• I was going to add this answer as well and will add it is actually true historically (mounted armies and those with chariots have long preferred valley/low-ground fighting) and in modern times (tank + hill does not work well). – LinkBerest Sep 16 '18 at 14:03
• The Battle of Hastings that enabled the Norman Conquest of England was one such scenario, King Halrods Anglo-Saxon army held the top of the hill at Battle with a shield wall. This withstood many Norman attacks until Anglo-Saxon troops left that postion to follow Norman infantry that were apparently routing ( this may or may not have been a rouse). This enabled the Norman Cavalry to charge the Anglo-Saxons when they were on lower ground and won the Battle. – Sarriesfan Sep 16 '18 at 21:53

If the surrounding hills have trees or other flammable flora, perhaps a specialised fire unit could be positioned at the bottom of the hill where a fire is more likely to spread upwards, towards the attackers. Perhaps the rising smoke might initially obscure the vision of the attackers and prevent them from shooting down accurately (although the smoke might later accumulate in the low village. Could this specialised unit also be experts at fighting in low visibility or poorly oxygenated places, like mine-shafts for example?). Water from the village could be used to douse lower trees/bushes and prevent the fire coming down the hill or spreading amongst the houses.

This could lead to further quests if it’s the villager’s hillside crops that end up being sacrificed.

Two things, make use of knowing how they'll attack and have a reason the Village is in the valley instead of a hilltop.

For example: there's a grass that's extremely slippery on the hills, so the villagers avoid it (and perhaps harvest it). Enemies attempting to charge down the hill might break legs, arms and necks even if the defenders dont do anything.

The hills are dangerous. Natural gas deposits could create the 'eternal' flame sites we have in the real world. Besides igniting the gas, the natural bouyancy of the gas and the wind could make the valleys the only safe places, with enemies arriving sleepy from lack of oxygen or dead at the bottom after an attack. Other dangers on the hills could be extremely territorial animals like birds or insect swarms that deal with people who disturb their hills.

Sarlac pit like animals could live at the bottoms of the hills, or large versions of burrowing spiders or similar that make sure enemies/prey cant stop after the charge and are pulled in to be killed and devoured.

• Sarlac pit like animals giant antlions? – RozzA Sep 16 '18 at 21:37
• @Rozza yes, like large Antlion like larvae – Demigan Sep 17 '18 at 11:36

What you could use are pikemen. If enemy has only/mostly melee, they will have to charge down the hill. And if you ever ran down a hill you know that it is hard to stop. Even if it's matter of being impaled on pike or living. When they charge, then surprise! From shack near hill pikemen emerge and guide, in such formation that there are virtually no spaces in between. Enemy is just impaled!

Catapults/trebuchets and siege towers.. a castle on hill is still rubble when a big-ass rock smashes it. I'll also borrow this totally asinine weapon and suggest a variant built for a Ballista:

Because you can't defend what no longer exists on this plane!

Supposedly elephants struggle to run downhill.

I'm not 100% sure whether it's to do with how they walk or how their legs work, but if you were attempting to restrict a charge of elephants (or creatures that walked the same and/ or had the same kind of legs as them), a low-ground position might be beneficial to restrict their ability to charge your defensive lines.

Of course this is more predicated on what disadvantages an enemy has as opposed to the low-ground working to your own advantages, so it might not be applicable against all enemies.

You have an Ent-like species of warriors. The hills surrounding your city are made up of loose, shalely material covered by a couple of inches of top soil. When the enemy rushes down these hills thinking they clearly have the upper hand, your special force ents tear in to the hillside causing mini avalanches.

The ents are of course also rooted in to terra firma at the base of the hills. Those enemies not buried by the initial slide will be quickly dealt with by large, tree-branch-like arm clubs.

• But then the shale slides into the valley, covering you. – RonJohn Sep 14 '18 at 14:10

From Greek mythology, Antaeus was invincible as long as he was touching the earth. Perhaps you could work this hero into your story.

• Welcome to Worldbuilding! Can you please expand your answer to include how this point can be used in the story? – John Locke Sep 14 '18 at 23:38

The army will benefit from being downhill if it uses some kind of reusable missile that can return to them by rolling down the slope after being trown.

For example, if the army has a trebuchet-like weapon shooting big round stones, that stones can just roll back to them to be shoot again to the enemy. Of course, the army needs the ability to safely catch a big stone rolling down the slope while the enemy must not have the ability to catch the same stone when landing upon them.

Another example would be the mud hoses proposed in Onofre Pouplana's answer. If the mud slides to you, you can collect it and trow it to the enemy again.

Please notice that if the army were on the top of the hill, all those missiles will just roll away and you would soon run out of ammunition.

Camouflaged units have a distinct disadvantage at the tops of hills, where it's easier to see them silhouetted against the sky; they would be a good candidate for a force that preferred to fight on low ground. If they were well-disguised and lying in wait at the bottom of a hill, they'd be able to use ranged attacks to pick off enemy targets with ease at the top of the hill - even though gravity is working against them, the range is short.

They'd probably need to be spaced relatively far apart compared with a regular army, though (the camouflage isn't useful if the enemy can just shoot at random patches of ground and have a good chance of scoring a hit), so their overall effectiveness isn't as great - they'd be useful for softening up and demoralising the attackers, and leaving the rest of the fight to a regular army.

Realistically if you get low or below ground then you'd be in the ocean. Hard to target something like a Russian Sub laying dormant let alone hit one miles deep. With a wide range of missile types including a under water super sonic nuclear torpedo can address most enemy types. 2 Flying drones from below ground nearby would also work. 3 On foot in a fox hole or laying covered with camouflage for a pop up ambush on flatter ground. Didn't read the other answers yet for purity of my answer.

I up voted everybody. TKS

• What the heck did I just read lol? Low ground isn't realistically in the ocean...it can easily be a valley halfway up a mountain. Why is the sub Russian? – RozzA Sep 16 '18 at 21:46

Depending on your time frame and the training of the parties involved,the low ground could indeed be an asset.

Viking and early medieval armour consisted mainly of chainmail coat and helmet. The legs were often unguarded or had at least thinner protection than head, torso and arms. Now if your enemy is above you, it's easier to protect your upper body, especially if it's armoured anyway. At the same time you can strike at their legs.

Remember that you don't need to kill your enemy to win. Just make sure they can't or won't fight.

Since it has not been said, a platoon of army tanks.

The lowland is some disadvantage to the climber but to the tank, bring anything.

Big firing guns make thirsty work of those climbing hills. Clearway over between makes even armour needless, nonetheless, what every sticks and stones and arrows they can hurl will not hurt the tank and by the time they clear over lowland they will be obliterated.