What would be the primary weaknesses of massed archers?

Question

Setting: In my world, there exists a nation that has a military primarily made up of archers. Each citizen is required to have a level of proficiency with a longbow, both in individual shooting and massed shooting (as these are two different skills). They are supported by small numbers of sword bearing infantry, and elite archers mounted on flying griffin-like creatures. This militia is tasked with defending the homeland against a more historically accurate combined-arms force (think early middle ages levels of technology here). These opponents have armored cavalry, spearmen, swordsmen, siege weaponry, etc. They do NOT have any flying mounts, and have to try to resist attack from the air by firing back arrows of their own. The defending force has a small numbers advantage (think 5 for every 4 attackers) but is made up of almost entirely unarmored civilians, although these civilians as a rule are better archers than even those of the professional enemy army (the elite forces riding the griffins are nearly supernatural in the speed and accuracy with which they can use their bows, but make up less than 1% of the defending force and mostly serve as scout recon). Arrows are not an issue, as they've built up a massive stockpile. They face their enemy across a wide field, with a long wall similar to the Great Wall of China protecting their border.

Question: what weaknesses would an army made up almost entirely of expert archers have?

Heavy Cavalry would be very dangerous in the open field, but the wall helps a lot with that. Using trees or other cover to advance close before taking missile fire also makes sense, but there isn't cover for the attacking enemy here.

My current theory is that the terrain is favorable to their missile fire, but heavily armored opponents or the use of siege towers and large shields would render many of their advantages moot. I'm wondering if given the wall for defense (making the heavy cavalry charge much less of a danger), the final issues could be solved simply by having arrows capable of piercing the enemy armor. It seems that a defensive army armed with only bows would actually be very difficult to defeat if armor and shields are not enough to stop the missile fire.

Edit: This is perhaps obvious and something that I should have noted before... In response to the excellent answers and comments that have noted weaknesses/expense/why this would be difficult if not impossible for the archers... yes. That is agreed, and is in fact a plot point. The defending nation's focus on Archers creates both strengths and weaknesses for them, which will be exploited by the invading force, leading to a win for the invaders. However, I wanted to make sure that "arrows blotting out the sun" wouldn't just make an attack across open field completely stupid. Thank you for the answers/comments, however critical they may be ;)

Answer 1

Frame challenge: The scenario presented is implausible. No competent commander is going to assault well-built fortifications with an inferior force. If the commander does not have at least a 3:1 numerical advantage then they simply will not attack. (Especially in this situation - the lack of quality armour for the defenders is practically irrelevant if they are able to shoot from well-designed and solidly-constructed defensive walls.) In history there were castles that were able to hold out for as long as they had supplies with half-a-dozen defenders against hundreds of besiegers.

If the defending polity was small enough then it would certainly be feasible for the attacking force to lay siege to it, as the unarmoured archers are singularly ill-equipped to break a siege. (Vastly more cities have fallen to siege than to assault in pre-Renaissance times.) However, if we are talking a large defending nation with good logistics then laying siege is not an option without both a ridiculously large army and being willing to invade all the other nations that border the walled opponent, in order to complete the siege. (A "siege" by only one bordering nation is nothing but a border closure.)

However, let's for the moment posit the existence of a stupid ruler who nonetheless must be obeyed, who has told his general to "go forth and invade the walled nation of super-archers that outnumber you".

Assuming the general is competent, he will commence siege engineering works in multiple locations. The exact nature of these works will vary depending on the absolute army size of the attackers and the characteristics of the defending wall - I am not going to write a treatise on siege engineering here - but the attacker will concentrate on building ramps, undermining the wall with tunnels etc, all under the cover of large, portable shields and semi-fixed structures that provide some protection from arrow shots and near-perfect protection from observation (so the arrows cannot be aimed). During this stage the attacker will use their siege weapons to inflict casualties on the defenders - especially any archers targeting the engineers - and neutralise any siege weapons the defenders bring into play. (If the attackers have such a dominance in siege weapons that they can breach the wall from outside bowshot then that makes the next part almost trivially easy, but we shall assume that they cannot breach the entire wall with trebuchets etc.)

Finally, once works have progressed to the point where breaches are imminent in multiple areas, the attacker will breach and attack with heavily armoured infantry, each with a pavise, at a time when the archers ability to see and or shoot is impaired, such as night time or a wind storm. The basic rule of "the defender chooses the ground, the attacker chooses the time" lets the attackers move when it suits them, and once armoured infantry is in among the archers then it's all over for the defenders. (AlexP correctly noted that the English archers at Agincourt were both armoured and experienced at fighting in melee when required, but neither of these apply here.) With the attackers controlling a breach point then they can move their cavalry through to run down any archers on foot who try to flee and the archers get a painful lesson in why balanced combined-arms forces are a good idea.

One more point to note - against a really well-armoured soldier, arrows are not that great, even at point blank range. It is possible to dive deep into a rabbit hole over this issue, if you are game then I strongly recommend starting with this video from Tod's Workshop.

TL;DR - No one is going to assault a major, permanent fortification with a numerically inferior force against a mass of super-archers. If they absolutely have to try, then they will undertake siege engineering works over a period of weeks or months, then pick a time and place that provides the greatest advantage to breach the wall.

Answer 2

Except for the griffins, this is just typical ancient or medieval siege warfare

The defenders have a wall, and archers to shoot from it. The attackers have siege equipment. The wall is designed with crenellations and towers to maximize effectiveness of the archers while protecting them against return fire. Most ancient and medieval siege methods were designed specifically to counter archers behind a wall. The basic idea is to keep a barrier between you and the archers, usually wooden, as you slowly advance. Arrows won't go through a wooden barrier.

• Siege towers: the attacker is in a tall wooden structure, slowly rolling at the enemy. Arrows aren't going to pierce the structure. The attacker reaches the wall and uses the tower to get on top of it and claim the wall. The defender's walls may be sloped back to help prevent this (like a talus). They can also try to burn the siege tower, but the tower may be covered in wet animal hides to stop fire. The defenders might also try to crush the siege tower with catapult stones. Failing that, defense comes down to winning the battle on top of the wall.
• Covered rams: similar to siege towers, except there is a ram hanging inside the rolling structure to damage the base of the wall. Siege towers may also have rams in them. A ram won't be terribly effective if the wall is thick enough.
• Siege ramps: the attacker piles earth in a huge ramp to the height of the wall, so they can get on top of it. To protect against arrows while building the ramp, the attackers may use wicker mantlets. The defenders might respond by building the wall higher in the area in front of the ramp.
• Siege trenches: the attacker digs trenches in a zigzag pattern towards the enemy wall, so that he's continually protected from arrows by the earthen wall of his trench. This will get him to the base of the wall, and from there he may try to dig under it to cause it to collapse. The attacker will support the undermining tunnels with wooden spars that can be burned when enough has been dug.
• Testudo formation: the attacker approaches the wall on foot with interlocking shields held over their heads. The shields will stop arrows, but the attacker is still vulnerable to boiling oil and dropped stones, and even once they reach the base of the wall they may not be able to do very much from there. They might deploy picks to slowly damage it.
• Ladders: the attacker approaches the wall in large numbers on foot with many tall ladders, which they lean against the wall and climb. The defender shoots the attackers, or uses poles to push the ladders over and topple them. The defender can also pour boiling oil or drop stones on the attackers. The wall may be sloped backwards more at the top, like the ark of Bukhara, which makes it harder for a ladder to reach the top.
• Trebuchets: the attacker may launch big rocks at the defenders from beyond arrow range. This could cause minor damage to the wall and kill some defenders. The attacker might also use it to launch diseased bodies over the wall as a form of biological warfare.
• Outlasting the defenders: the attacker might just have more resources and more staying power to conduct a siege. You said the defender's wall is like the wall of China, so the defender in this case probably can't be starved out.
• Relying on treachery: a defender might be persuaded to betray his own people and open the gate for the attackers.
• Just going around it: you said the wall is like the wall of China, which is not a continuous wall. It's very hard and very expensive to wall off an entire country completely. (See also, the Maginot line.) The attacker might just invade the country somewhere that there isn't a wall.
• Build a wall around the defender's wall: this is called a contravallation if the wall faces the defender, which prevents the enemy from sallying out from their fortress to mount a counterattack. It is called a circumvallation if the wall faces away from the defender, which prevents allies of the defender from mounting a counterattack.

Note that, generally speaking, once the attackers have breached or climbed the wall and actually begun to fight in melee, a man with armor and a shield and sword/spear is usually going to be much more dangerous than a man with a bow. Armor does work. There are exceptions (Agincourt) but having 97% armor coverage against arrows really does usually mean you win, once you're finally face to face with the archer. Also, friendly fire becomes a major issue as soon as the enemy gets into melee range with the mass of archers.

One thing in your scenario is not typical siege warfare: the griffins. If the griffins make up <1% of the defending force, call it 1% of the attacking force, that's actually quite a lot. A lengthy siege by the attackers won't be possible. The griffin archers can constantly harass and kill the attacking forces in their camp, from an altitude the attackers can't reach. If each griffin archer manages to make one kill a day from an altitude that makes return fire impossible, then after 10 days 10% of the enemy is dead, which will crush morale and may force the attacking commanders to retreat. Medieval or ancient sieges typically lasted months, so 10 days is comparatively very quick. The griffins could also lift and drop boulders from miles up to smash siege equipment before the attackers finish building it.

Answer 3

Following from AlexP's fine reply - the main weakness of massed archers may be the expense of maintaining a unit of any size. They could also only maintain the dense bombardments for minutes before they ran out of arrows.

The solution in Ancient Syracuse was the Gastraphetes or belly-bow. This was an early crossbow that was cocked by pressing it into the ground by leaning on it. This got around the problems of training an archer to hold a drawn 140-lb bow steady enough to aim it, but was quick to cock, unlike mediaeval crossbows which could take minutes to crank. It is not known exactly when this was invented; there are several theories mentioned in the article, but the rulers of Syracuse of that period had an intelligent approach to military R&D, and they could well have reasoned that this was the cheapest and quickest way of turning a conscripted militia into accurate-enough archers.

It may be sensible to back up your wall defence with ballistas. These have a lower fire rate, but they can deal with heavy armour. That can be used to pick off any individual targets that get too close.

Answer 4

This was much like the situation with the English in the early 15th century, around the time of the battle of Agincourt. As with the OP's defenders, the nation has an abundance of common people who have been encouraged to practise archery, however beyond their bow and arrows, they are poorly equipped.

However, poorly equipped does not mean that they are incompetent or stupid. Citizen militias of this size would include people from all walks of life, and whatever the task at hand, there will likely be some militia members who can do it, whose day job involved doing whatever it is.

Another feature of militias of this sort is self preservation and pragmatism. The militia members will naturally be interested in self-preservation, and will make good skirmishers. Similarly, as was demonstrated at Agincourt, militias are concerned less with honour than winning. At Agincourt, French knights taken prisoner so outnumbered the defenders that even disarmed, they could have overcome the defenders. The order was given to kill the prisoners. The English knights refused, but the militia archers did not.

The proper use of militia archers is not in a stand-up battle, but as skirmishers who attack from cover to inflict attrittional losses upon the enemy, then disappear before a proper response can be mustered.

By causing enemy casualties, including among the better equipped enemy troops, it would be possible for the archers to appropriate their armour and eventually form units of heavy archers capable of standing in battle.

If these militia archers were misused, their lack of armour, lack of close-formation manoeuvre skills and lack of hand-to-hand combat skills would prove to be a severe liability, that could lead to them easily being overwhelmed and routed in battle, but properly used, their skills and mobility can be used to inflict disproportionate losses on the enemy.

Answer 5

Sappers

The enemy camps just outside of bow range and tunnels under the walls.

Bows are completely useless against sappers.

Sappers have two options, they can open up a tunnel to allow infantry directly into the enemies camp or they can tunnel under the walls and collapse the walls. Either way, archers are in trouble.

See Sappers

Answer 6

Frame challenge:

Your defenders cannot possibly loose barring some large scale treachery. Even without griffins it would be extremely hard for your invaders to win as they don't have numerical advantage. And cavaliry being a counter to archers doesn't mean much if the defenders have walls.

But the issue is in the griffins. They don't need to fly all that high for them to be impossible to hurt by bows. Let's look at the numbers: an english longbow shoot an arrow with the speed of 170 fps (or in proper units around 52 m/s). If they would shoot directly above the maximum height the arrow could hit is 135 m. Mind you, at that heigh the arrow would have the speed of 0 m/s, so being hit wouldn't do anything. Even at the height of 100 m the speed of an arrow would fall to around 26 m/s which has drastically lower penetration power - thick leather would be enough to stop it. BUT! Archers generally cannot shoot at targets that are 90 degrees up. Not that it would be a smart thing to do anyway, as missed arrows would hit their own men! So if we asume 45 degree angle, something that archers actually train for, your maximum height would be lowered to 68 m.

So your griffin archers could easily fly at the height of 150 m and the attackers could do absolutely nothing to stop that. And since birds can easily fly at heights in 1000s of meters (and bats at the heights ranging between 500 m and 1500 m) that height shouldn't be an issue for a flying creature. So they can shoot at the enemy at leisure. You don't even need the riders to be good archers. If they are then good, they can kill the enemy's officers. But even bad archers can be a danger if they can shoot from safe distance. Or they could throw burning oil on the enemy camps. Or they could attack the enemy's logistic chains. Or go for a raiding strikes into the hearth of the enemy's territory to destroy the invading army's morale (it is kinda a morale killer if you destroy a village of civilians for every day of invasion).

In short, your air supperiority combined with fortifications makes your defenders practically unbeatable on the field of battle. You can defeat them only by taking advantage of internal strife or sabotage.

Answer 7

The weakness that the defenders have is the standard problem of defense: defending a long wall means either being weak everywhere or being weak everywhere except for one place - where the enemy doesn't have to fight.

The attackers will march faster than the enemy can detect the march and redeploy, escalade the walls and win by default, because the defending army isn't there.

Other answers and comments seem to think this is like a siege of a fort. This is geometrically incorrect. A border wall isn't a circle, to have interior chords much shorter than extended exterior circumferences, and hence defenders that can always detect and redeploy faster than the attacker can move. It's a long squiggly line.

The attackers will be on the other side of the wall in a few days, or a few weeks if they need to cut roads and build bridges. Very little violence will be done in the process. The violence will start after the walls have been lost. Towns and villages being raided, then forts and walled towns being conventionally besieged. There may possibly be one or more field battles if the raiding brings the defenders to battle.

The attackers' approach is straightforward.

1: get a map and/or or some local guides. This will let you choose a region where the enemy’s lines of communication are longer or more impaired than yours. Squiggly lines have convex and concave parts, so you get to have interior lines, even though you're the attacker. Modify the region (e.g. by clearing roads, building bridges) if needed. You get to pick the time of the fight, so you get to take your time getting ready to decide the place.

2: press your information advantage. You get to know when you're leaving and where you're going. The enemy has to wait to find out. Enemy air superiority reduces this advantage, but it doesn't eliminate it. Deception, especially hiding when you're preparing to break camp, increases the advantage.

3: just be faster. Your guys are professionals fighting civilians, and the railroad is 600 years in the future. They can muster faster, march faster and farther in worse weather, make camp faster, break camp faster, and transition from march to battle faster. This is probably all you need by itself. If you can travel as far in 3 days as they can in 4, you eat lunch on day 4 on the far side of the wall.

Ultimately, you just march right up and over the walls without significant resistance, then set about ravaging the countryside. If it ever comes to a field battle, heavy infantry with shields can be expected to rout the archers, then you get their baggage, and logistics will take care of the rest.

Also, fight in the rain. Medieval bows sucked when they were wet.

Answer 8

Height may be a key factor in such a scenario. Given that your archers are riding griffin-type flying creatures, each archer has to ensure that his/her griffin is safe and capable of holding its own in the battle. Since your archers are extraordinarily trained, they may be at a good height above the battle zone and still beat the pulp out of the enemy.

Problems may arise when some of them decide to lower their griffins. The opponents have swords and spears both of which are excellent weapons for short range. When the opponents will see you at low enough height, they will throw swords and spears at your low flying griffins and their riders.

Another problem might arise when some griffin riders take a lower height to fly than others. They might hinder the targets of those flying higher than them. This doesn't mean they are bad archers. As you say they are very good at it. But an archer flying low doesn't know which way the upper flying archer is targeting and may unknowingly come into his way and might get killed. This is like when it rains fire on battlefield your enemy as well as you are prone to burn. So the archers need to fly at roughly the same height deciding amongst themselves and according to the demands of the battle could they maintain the appropriate collective height.