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It seems to me that your angels wouldn’t be invincible, impossible-to-defeat warriors with the parameters you’ve set. Like other answers have said, since they have to land eventually, they will be vulnerable to the other, larger races in your world. While they would be excellent raiders and quite powerful warriors (a wine skin filled with flammable oil and flint would be a terrifying weapon when wielded by these creatures), they would find it hard to hold ground in tight, crowded spaces such as canyons and forests, and it would be nearly impossible for them to fight underground. They would naturally have an advantage in and around things like tall mountains where they could fly and maneuver freely, attack without any obstruction, and fly back to resupply. While no one will be able to out-raid the angels, they will have a hard time defending anything that isn’t sheer cliffs because of their need to strike and retreat to avoid being grounded.

As for how to defend from an attack, look no further than the phalanx. Most of your other creatures seem to be larger and stronger than the angels, so have some of them carry large, powerful shields with angled metal plates. That way fire can’t burn the shields and impact will be deflected off. Since the angels have to get closer to the ground to be accurate, they will then be open to archers firing on them, especially considering that some of these races sound like they could handle firing really large, powerful bows.

Also, one last consideration. Things like storms, high winds, or even smoke from wildfires would make it very difficult, if not impossible, for your angels to fly. Without any sort of magic, your other races can set fires and use the smoke to limit where the angels can fly, and thus make them at least slightly more predictable.

Since your angels are light, flying entites, they probably can't carry much. The more they carry, the more slowly and laboriously they fly, and as a result, the better a target they present themselves.

This would, naturally, lead to light armor and armaments, think leather armor and your earlier mentioned projectiles - stones, spears, etc. But in order to be effective, a projectile has to weigh a certain amount to do damage, otherwise it will just bounce off of any lander's armor. So the weight of the ammunition itself limits the amount of time they can stay in combat.

Imagine that the most common spear weighs (for math's sake) 1kg, but the max an angel can carry while staying airborne is 10kg. That means once they loose their 10 spears, they are out of the fight and must go resupply! Or they can go fight on the ground, but then they are at a clear disadvantage. And their resupply base must be on the ground somewhere, so a smart enemy might find it...

A 72 Kg meatbag, flying four clicks above a target, with only medieval weaponry, would have a very hard time hitting a target accurately.

Sure, they can fly lower and use bows, but there are only so many arrows you can carry.

At some point they have to land. They can't sleep, cook, make love nor nest in the air. And once they are on the ground, they are game.

At the very least, burn their tents to the ground, and they will have to fly back home for more supplies.

Choose your terrain. You can't fight in plains or fields, that'll be a lost battle for the rest of your creatures. Fight only on dense forests with high coverage. With 4 meters of wings, they won t be able to maneuver bellow the leafs and from the sky it will be harder to shoot their arrows accurately as they would need to beat the resistance from the top of the trees.

Also have your spider people lay webs all over the region they want to defend. If any angel tries to fly between the trees they will be trapped and an easy target.

Have the elves hide on top of the trees and shoot down any low flying angel.

Attack their nests with lizard people, because they probably have a high and almost impossiblen to reach location. They can climb better and stealthly disrupt their rankings.

The merfolk are safe, as long as they don t leave the water.

If I were tasked to defend against these critters, I'd consider it an easy (but interesting) job.

Preface: In a medieval world, you need to take the castle to control a land. As long as the castle is in enemy hands, so is the land, whether or not you have your troops there. So this is all about defending your castle against some tasty chickens. (are they tasty?)

First, castles already have roofs above the battlements, typically, to defend against ballistic arrow shots. They will work just fine against arrows, darts, spears and light stones dropped by these critters.

And if they want to get any kind of accuracy, they will have to approach much lower than their maximum flight height. Chances are good that in a battle they will be within arrow range. Fill the air with arrows and watch them coming down - they won't be able to carry much in the way of armour while my men on the ground can hide under roofs, behind shields and wear all kinds of protective clothes.

In addition to that, I can certainly modify my trebuchets and other heavy artillery to throw things upwards, and then load them with cast nets, possibly modified for this type of deployment. Basically, I'm putting a net into the air. Try flying with your wings tangled in a net.

And just because I'm vicious, I can play havoc with their aerodynamics by liting a couple big and hot fires. If I can hide the flames and smoke, e.g. by making the fire inside a building and using something that burns clean, they will swoop over my castle and suddenly find themselves in a violent updraft with turbulences. Good luck.

And finally, as soon as I have cannons or something else powerful enough (I might check if I can modify a ballista) there is the old and effective weapon against anything that flies: Scattershot. Instead of shooting one big-ass bolt, my ballista can shoot a hundred smaller ones, or my catapult can throw a whole load of gravel and sharp, fist-sized stones. Aim would be terrible at first, but my people would learn fast.

So there is a whole lot of pain I can do to the birdies as soon as they come down to low heights, and I can force them to come down there because if they stay up high I'll just hide under a roof and laugh about them. In fact, if they just drop stuff from up high, there's not much of a tactical difference between them and an array of catapults on the nearby hill.

So, how can Angels be stopped from taking over the world and create an Angel dominated empire where every other humanoid creature just gets enslaved?

Weapons and warriors can only win you a battle. Wars are won with logistics.

Look at most powerful modern machines of war, the aircraft carries. Do they pack any weapons? No. All they do is provide logistics for planes. That's all that it takes.

No matter how good your angelic warriors are - fighting is exhausting, flying is exhausting and doing both is probably exhausting squared. They need to land, rest, eat and rearm. And from your description they sound to be absolutely defenseless then. If they don't have ground infrastructure: beasts of burden and heavy wagons, they can't take any supplies with them. They can't perform what empires hinge on: "projection of power". They're pretty much limited to defending the nearest vicinity of their settlements, range that a warrior can reach in a single flight, be able to fight and return home. Sounds like no more than few hundred km. Altitude can be used to avoid a fight, but not in combat. If an angel flies low enough to hit someone on the ground, the soldier on the ground can fire back. Ground troops can carry heavier, longer ranged weapons like crossbows and ballistas. Aerial attack is not radically different than what is already well known. Volley of arrows fired in an arc fall from above just like a volley of arrows fired by angels. All other races already have worked out their combat tactics against that, eg Romans had turtle formation. Flight can give advantage of speed and surprise, but not a 1:1 advantage. Also, unlike ground-based armies, they can neither take prisoners nor care about their own wounded. Most wounds would mean either death falling or forced landing - which means death on hostile ground as well. Angels would probably have much different social values because of that: either being very pacifist to avoid loses or on the contrary, praising death in combat as a method to cope with high loses. You mention cross-continental flight, but you don't say anything about it's consequences. Birds do fly 10000km in one take, but they take months to prepare for the migration and weeks to recover from it. That's not something one can use offensively.

I don't think your problem is "how they didn't took over the world". If an enemy attacks, can survive the first defensive strike and continue marching to reach the settlement - angels are toasted. I'd worry more about "how they've even stayed alive". That's stereotypically solved with having them perched on high mountains, inaccessible by foot. Note that it limits their development, so their weapons would remain crude and ineffective. It's probably a vicious circle: angels can't leave their high perches because they lack technology to be competitive on the ground and they can't develop the technology because they can't leave their perches.

PS: I think you're severely overestimating physical power of a creature that consists mostly of flight muscles. They take most of your 72kg, the rest being vital infrastructure like gastrointestinal tract, leaving almost no mass budget for arms, legs and weapons, leaving armor out of the question entirely.

It comes down to the terrain where the other species live

• Half human, half lion centaurs - Open plains? If the reside in caves
  then aerial bombardment is pointless


• Elves - Forest? Kinda hard to
  spot people in the trees and likely to get shot if you get closer.
  Burning the whole forest is the only way to win.


• Driders or giant spiders - Underground or dark places is no place for an angel


• Lizardfolk or reptile people - Swamps? Just like a forest only wetter and impossible to burn.


• Merfolk - Underwater is completely untouchable


• Nagas - Swamps again?

Aerial advantage only goes so far and if forced to go hand to hand, suddenly they are at a disadvantage.

The only real advantages are spying and burning out crops and other food supplies.

The most likely weapon these angels would carry would be something like Javelins, or since throwing is likely impeded during flight they would resort to dropping tiny darts (https://www.google.nl/amp/s/www.dailymail.co.uk/news/article-2662730/amp/WWI-darts-dropped-biplanes-German-trenches-disgusted-British-aviators-ungentlemanly.html)*

Still you are heavily impeded by accuracy. For proper accuracy you need to aim for formations or fly low and risk retaliatory fire. This means angelics wont auto-win battles.

Theres also resource management and population. If only 5% of the living sentients is angelics then they wont be that influential in the grand scheme. And imagine if your angelics attack a nearby Village and say "do our bidding or we'll kill again", upon which the villagers send a few people trecking across the ground and burn the angelic's food supplies and hunt whatever the angelics eat till they starve. Flying means they need to eat a lot more so they need a much more nutrient rich diet and run into famine faster if you target their food. This means that angelics are better off banding together than enforcing a kind of slavery.

*Edit: for reference these darts were thrown in batches of 500 which would be hard to pull off by an angel. In a test scenario on a luckless cow 3 out of 500 hit and went straight through the cow and into the ground, so in one hand accuracy is definitely a problem but even with inferior darts the killingpower wont be.

The weaknesses and disadvantages of angels in combat have already been covered - I'd just like to add a couple of points regarding anti-angel tactics.

Fortifications - If people are fighting angels regularly, they can adapt their fortifications and defences to compensate for an airborne enemy. Covered battlements with fireproof sloped roofs would shelter defenders from attacks from above. Arrow slits or hatches they can pop out of would allow them to return fire whilst minimising exposure.

Siege Weapons - Most medieval siege weaponry fires one large projectile and is optimised for dealing damage to fortifications and building. With the right motivation, anti-air siege weapons could be designed and built that fire dozens or hundreds of lighter projectiles that would prove deadly to a lightly armoured airborne combatant. For reference, think of something like the Hwacha, which uses small fireworks to launches dozens of arrows simultaneously. If gunpowder is unavailable, catapults and trebuchets could be modified to fire shotgun-like blasts of small rocks and sling bullets.

Since most other answers discuss drawbacks to being an angel in combat i'll talk about anti angel tactics. since this is early 1000s, you most likely don't have crossbows, but you would want a way to damage the flying creatures fragile wings some how.

You could have a battalion of sling users, they could lob stones and early lead bullets at angel in a synchronized volley. This could be vary hard to counter, shields would really weigh down the angel and you cant cover everything.

Since Merfolk exist you could easily adapt fishing nets to be launched at the angelic folk when they get low or on the ground.

I'm going to answer your question "So, how can bird people be stopped from taking over the world?" with a question (yeah, I'm that kind of guy) -

3.8 Kilometers means that the Angilians (Angel-avians) are adapted to lower oxygen and air pressure and would therefore prefer higher altitudes. In lower altitudes they'll be quite uncomfortable. Why do they want to take over your plains and forests, then? Must be something that you have, that they don't (seems that control over your land isn't it).

Once you figure what that thing is, base negotiations upon it. The reason could be as simple as a fear that your people will one day take over their land (which is similarly dubious, for the same reasons). Once everybody figures out that continuous war isn't beneficial in the long run, put up some Peace and trade agreements that will serve both sides, and these will eventually lead to a grudging co-existence.

At least until those grudges/religion/racism/sheer stupidity bring about another inevitable skirmish... So, people beleaguered by attacks from above are going to develop fast roof-construction methods. Crawl towards the bad guys' city with your wooden tents/shacks and kick their ass... until they kick your ass... and the cycle begins anew.

they only walk when home or when resting.

Then that's where you fight them.

EDIT: specifically, you (the terrans) need some serious advantage when fighting the enemy (the avians) on the enemy's terms, and your question sets it up that the terrans are disadvantaged. Thus, the terrans must fight on their own terms, which means tracking the avians to their resting places, or sabotaging their food/water, etc.

I'm having another idea:
What about flying nets?

Inspired by a game where an archer could shoot a net with 4 arrows, which stunned the enemy for a short time. When applying this principle to this question, it would mean shooting nets at angels to block the wings and let them fall into the death.

The nets need:

• to weight very less and be so strong to get not destroyed by the power of the wings


• a diameter of at least 5 meters, better 7m


• skilled archers/slingers or a catapult to hit properly

The advantages are:

• nets cost not much


• nets are easy recycleable


• -> what means special nets (with barbs or else), which costs more are also available


• very effective (if performed right)

The disadvantages are:

• It's hard to perform right, you probably need a catapult for shooting


• somebody has got to collect the nets

I hope this helps :)

Here are a couple of things that would keep the bird people from being anything but the terrorists of your world:

1. They can only fight what they can see.


2. They can kill but they can't hold ground.


3. Their path to success is cooperation, not conflict.

They can Only fight what they can see

They can't effectively fight at night. They can't scout forests or any terrain that provides overhead cover. So, enemies need to move at night and hide during the day. Once they get near the flyer's base, they can attack at night (possibly with crossbow delivered nets).

They can kill but they can't hold ground.

The flyers should be physically weaker in hand to hand combat than a normal human unless there is magic involved in their flight. They need to keep their muscle mass down and most of their muscles will be powering their wings. They would have to fly into an area, make several trips to bring supplies forward and then begin raiding. Even in the raid, they still have to get their loot out. They better attack someone that has something with more value to weight than the arrows they will bring with them.

They would never be able to have towns or cities in a contested area.

The will not be as good at farming as a human (the wings don't help plow the field). So their food supply will be less than human's. Thus, their population will be less than a human's. They could raid for food but how much food can they carry and how many will they lose on the raid to do that? Even then, all it would take would be a couple of fake food shipments (either with fighters hiding in the food or poison in the food) to end that.

Their path to success is cooperation, not conflict.

In a caravan, they can scout for bandits or beasts and at night, they can have a bunch of those strong humans guarding them while they sleep.

In an army, they can scout or snipe high value targets while, at night, they are surrounded by an army of people who have a vested interest in protecting them.

First off, there is much more to conquering the world than being individually formidable.

If someone else is more numerous, more organized, more aggressive, smarter, better at diplomacy, or just had a head start, they may dominate your bird people even if the bird people are individually more capable in a fight.

Your bird people would have inherent problems with logistics. They either need flying pack animals, flying machines, or they need to carry everything themselves. If there are flying pack animals or machines, the other races will be trying to get their own for flying cavalry, flying dragoons, or an air force.

The small wingspan of your bird people isn't going to allow for extended soaring. They are going to need to land reasonably often to rest, and they are going to need an enormous amount of food (which makes the logistics problem worse). Heavily loaded flying pack animals will also need to rest often and if they don't have flying pack animals, their own range is going to be further constrained.

Siege warfare has plenty of tactics for defending against people high above you dropping stuff and your bird people would have some trouble with managing a really dense sustained, attack since they can't pack closely together, they need to keep moving to remain flying, and they can only throw what they can carry with them. So sure they can harass with impunity and slow their enemies down quite a bit but unless they have something like antipersonnel grenades. I don't think they are going to be able to entirely stop an enemy that's prepared to defend against air attack by just dropping stuff. This makes them ineffective at taking and holding land.

On the other hand, I think you are missing one of their most important military advantages: reconnaissance and communication. Even if they were to largely manoeuvre and fight on the ground to conserve energy and resources and so they could carry a heavier load of gear, the fact that they could have flying scouts and "runners" would be a massive advantage. It would also be one that the other races would be eager to match, meaning they would encourage defectors.

So overall, I don't think you need any special contrivance to stop them from taking over. You would need to give them more than just being able to fly before it became a problem.

Burning Mirrors / Heat Ray

Inspired of Archimedes who supposedly used this technology during the Siege of Syracuse (214–212 BC) one can imagine towers equipped with big mobile mirrors in order to concentrate the Sun beams. Just point the beam to your avians and see their wings starting burning !

It has been shown that Archimedes wasn't abble to perform such a trick because argentic mirror weren't invented yet but this is not a problem for you as the first silver-mercury amalgams have been used in China as early as 500 A.D. !