# How to realistically implement magic-users in medieval warfare?

So, I’ve seen other settings before where magic-users – mages, sorcerers, wizards and similar – are basically gods. There have been fantasy stories where a mage can singlehandedly wipe out an army, and no mundane man could challenge them. In those settings, the mages typically have forcefield shields, endless magical bolt attacks, flight, telepathic communication or whatever.

I would like to strip all of that away, and ask what is the best way of implementing of a more limited form of magic during wartime? How would mages realistically be used in battle and warfare?

In my world, magic is a concept that exists but there are pretty hard limits on how much of it a person can use. Firstly, I'll highlight the levels of power that I'm considering.

Basic assumptions:

• Mages are all imperfect humans. Like any regular soldier on a battlefield, a magic-user is prone to miscommunication, friendly-fire, or even panic. Come battle, a mage requires training and command to keep them in formation,
• Besides a defined number of spells, mages do not have any superhuman capabilities. Their reaction speed, their awareness, and their durability are the same as a regular person,
• The quantity of mages is limited in number. It requires a large amount of study to use magic, typically decades. Due to the time and dedication involved, most experienced mages tend to be quite elderly,

Restrictions of magic:

• A mage can typically cast a maximum of three spells per day. After casting three spells, they require a full day to recuperate their strength,
• After every spell, it takes around one hour of recharge time,
• It requires intense concentration to cast a single spell,
• There are serious, life-threatening consequences involved with casting too many spells too quickly,
• Magic works in short, powerful bursts. A typical spell lasts no more than a few seconds,
• It is impossible to maintain magic for any extended period – attempting to create and then maintain a magical barrier would drain the mages very, very quickly.
• A mage requires direct line of sight to the target to aim the spell,
• The power of a spell is inversely proportional to its range. If a mage tries to target something a long distance away, and the energy will dissipate over that distance. The range of a spell is approximately half that of a longbow,
• There is a trade-off between power and precision when casting magic. For example, a mage could launch a large fireball into enemy lines, but that would be difficult to control and he wouldn’t be able to aim very well. Alternatively, a mage could launch a concentrated beam of heat to evaporate a single enemy’s skull, but that would require a lot of focus and he wouldn’t be able to put much power behind it,
• To cast a spell, a mage must be holding a large, two-handed staff,
• However, there are no restrictions on their clothing or armour. A mage doesn’t need to wear robes, he could wear full-metal plate. Likewise, before and after casting, the mage could swap weapons to hold a sword and shield if necessary,
• Magic originates from the caster’s staff and requires a direct medium to reach its target. A mage cannot telekinetically crush a man’s heart with magic, for example. The mage could only crush a man’s heart if he placed his staff directly against the man’s chest,
• Depending on the circumstances, a spell can be blocked or deflected,
• A spell cannot work passively. There is no such thing as a magical shield,
• Enchanting or imbuing other objects with magic is not possible,
• No spell exists that allows far-seeing, scrying, or instantaneous communication. The most that a mage could do is fire up a signalling flare,
• No spell exists that allows direct mind control,
• No spell is powerful enough to significantly control the weather.

Capabilities of magic:

• Most mages use and specialise in elemental control, but other specialities exist.
• There are quite a variety of different spells that can be cast, usually limited only by the caster’s own skill, power and focus,
• For example, a mage could cause the surrounding air to spontaneously combust into a fireball. He could also gather static in his hands and generate a lightning bolt. He could also telekinetically create a fissure in the ground beneath him. Alternatively, he could pull moisture from the air, or manipulate air pressure to form a shockwave. However, they are limited by peak power,
• For a rough approximation of their maximum power, a mage might launch a fireball with a five-metre impact diameter,
• When faced with a solid castle wall, a mage would be able to create cracks in the stone and tear it apart, provided that he was close enough proximity. This could be used to break through walls, gates and fortifications, no battering ram required,
• No single type of spell is ‘fixed’ – there’s a large amount of freedom for creativity during casting,
• Manipulating light and creating hollow illusions is possible, but again these illusions are restricted in range and duration,
• It also possible to mages to ‘curse’ or ‘hex’ individuals. They can artificially induce the symptoms of various ailments or diseases against their enemy. This requires a lot of focus,
• Most mages have one or two speciality spells, depending on the individual. A mage can often perform their preferred spell with great efficiency, but they would struggle to cast any other different spell.

The above are general guidelines – there are some individuals that would be stronger, others are weaker, but that’s about what a commander could expect from an average mage.

Basically, mages are like cannons that can fire very infrequent, very powerful, short-range attacks. However, unlike cannons, they are fleshy men in the middle of the fighting.

I imagine that a magic bombardment would be very good at breaking through walls or scattering a cavalry charge. However, a skilled archer can still outshoot a mage by quite a large margin, and so mages would still be very vulnerable to a hail of arrows. Archers can fire a lot further and a lot more regularly. In the thick of fighting, the enemy would probably train their marksmen to target any figure holding a staff.

Also unfortunately for mages, they do need to be on the front line to be really effective. They don’t have the range of siege weapons. You could guard them with a shield wall, but the mage still needs line of sight and a clear target to fire a magical blast.

So, the question: how does the existence of mages of this level affect military warfare and strategy in this world?

Let us assume that you are a general; you have an army of conventional forces (such as archers and crossbowmen, infantry and spearmen, knights and mounted units, etc.), and you also have a limited number of mages to support them. Let’s assume a few dozen mages among a thousand men. What is the best strategy of using these mages in battle, bearing in mind their effectiveness and weaknesses? What formations do you use, how do you get most use out of them?

I’m especially interested in consideration of different types of combat. How would mages influence a pitched battle? Or what about when besieging a castle? Do you use them differently during skirmishes or raids, or is there a better place for them off the front lines altogether?

Also, what do you do when the enemy has a larger number of mages in his army? How do you defend against them?

I have my own thoughts on the subject, but I’m curious to see what other people suggest.

• I'm tempted to vote to close this question as being far far too broad. There is just too much here and it would be impossible to give a concise answer, as the range of possibilities is too open-ended. – pluckedkiwi Aug 24 '18 at 13:26
• What about spells to heal or purificate things? Can a Wizard purificate water or food? – Sasha Aug 24 '18 at 15:29
• Have these mages been around forever, or are they a more recent development/refinement? – Brizzy Aug 25 '18 at 4:41
• I think the restrictions and capabilities constrain this plenty enough to be a well-posed question. For inspiration, I might look to Practical Guide to Evil for examples of well-thought-out (albeit somewhat different mechanics) mages in a medieval battle setting. – imallett Aug 25 '18 at 6:20
• There's a discrepancy in your tale. You expressly forbid anything that lasts for a long time, but you are able to hex or curse individuals with artificial symptoms that apparently last for extended periods of time. – Demigan Aug 25 '18 at 7:44

In this world you've created, mages are essentially more flexible forms of ordinance. In that way, as colmed suggested in their answer, you can look to how modern or renaissance war deals/dealt with that technology.

Here are some other things to consider:

• The point of a battle is not to kill every enemy soldier. The point of a battle is to convince the enemy soldiers that if they don't run away right now, they will die. So, as with any military asset, you want to be clever in how you employ mages, and they may be best used to strategically frighten and surprise enemy troops. For instance, if you pin down an enemy unit with infantry, and then hit them from the flank with magic that goes boom, that unit will be more likely to break. Sure, arrows may kill more of the enemy than a spell, but do arrows go 'boom?' No, no they do not.
• Deception is a big part of war. There are lots of ways to use mages to deceive your enemy, especially in crucial seconds of a battle. But moreover, you could deceive your enemy about your mages. Remember, the mere presence of mages on the battlefield is frightening. But how can you tell a mage is a mage before they start casting spells? By their staff? By their robe and wizard hat? Anybody can wear those and pick up a fancy looking staff...
• Given the ranges involved and the fragility of the human mages, they may not be what you want to commit at the beginning of the battle. It's easy to imagine battles being somewhat of a rock-paper-scissors situation: archers kill mages, melee troops kill archers, mages kill melee troops. Now obviously this is an oversimplification and depends on the specific battles, but I think you can build battles around trying to waste your opponent's archers' ammunition (or killing all the archers outright), and then subsequently bringing your mage corps to bear on the infantry. Or you could sucker your opponent into thinking they've killed all your archers, committing their mages, and then revealing your secret stash of longbowmen to rain death upon the mages. The possibilities are endless!
• Cavalry mages?????
• As you say, mages might be very effective as siege engines. Being able to walk up to a city and knock down a wall without having to build a catapult or drag it along with you drastically changes the math. Siege tunnels become much more dangerous too, since it can bring your mages close to the wall without risk.
• You might also have (mercenary?) units that are mixed mage/warriors. So, for instance, they each know one spell, fire it into the enemy, draw their swords, and then charge. Swedish musket pikemen did this to great effect in our world, firing their guns, dropping them, and immediately charging into their adversaries. Check out King Charles VII of Sweden and the Great Northern War.
• Mages themselves will try to make themselves seem scarier than perhaps they are. Sure, your mages are pretty limited, but superstitious soldiers don't necessarily know that. For thousands of years, hucksters have been convincing people they're magic... imagine if those hucksters could actually do some magic. You could have a school of mages the pretend that they can perform multiple spells in an hour by having one mage stand up and make big, impressive motions, while his colleagues do spell after spell, one at at time. If you used that school in your mage corps, other countries might be loathe to attack you because they think that school is significantly more powerful than their own. Or culturally, it may be a closely guarded secret that mages need time to recharge... I, for one, wouldn't want some punk with a knife to know that I used up my one-spell-for-this-hour blasting his buddy to smithereens.

Now that you've set the limits, you get to decide how your characters work around those limits, and how your cultures have built themselves to deal with them. You said it yourself: mages are just people, so they're going to get creative... and stubborn, and thickheaded, and brilliant, and sneaky, and arrogant, et cetera. This is the fun part!

By far the best way to use your mages is manipulating the environment. Have mages erect barriers of dirt, dig trenches, cause landslides, dig holes to make choke points, flood the enemies camp at night, damage the battlefield to halt a charge and pave transport routes to make supply lines more efficient. Risking the lives of such great support troops by having them actively participate is something a foolish general might do, and he will lose to a support mage using general 95% of the time.

And of course, most mages probably know earth and water magic. Do you know why? Because their main job is probably cultivating fields. Tilling swaths of land easily, ending a drought by launching water out of the river into the sky above fields. Digging waterways through hills that a normal farmer couldn't. Paving roads much flatter and harder on trading routes than any normal person can. Breaking up large sections of rock in a mine like an early version of dynamite. Basically mages would be a separate class above peasants but below nobility, where they do work, but only as much as a mage can do a day. A delicate balance of maximizing a mage's abilities but not pissing off a man who can shoot lightning at you. Of course they can't rebel because of their archery weakness, but a noble will prosper if he keeps his mages happy and working, so he tends to treat them better than the average serf.

• Aka, take a peek at Treantmonk's Guide to Wizards: Being a God for D&D 3.5: God: This is the role this thread is based upon. Three kinds of wizards alter reality so that the Glass Cannon and the Big Stupid Fighter think they are better than they are. Those three wizards are Battlefield Controllers, Buffers, and Debuffers. Your best bet is to do a bit of all of them - but you can make wizards exclusive to each role as well without sucking. – Matthieu M. Aug 24 '18 at 19:45
• I like this one. Mages are support personnel. They might be medics or combat engineers or providing food / water. If you have mages your regular troops will be more effective. – Willk Aug 24 '18 at 22:56

# Look at historical precedents for such a weapon

This 18th century Naval weapon was a large bore, short barrel, short range, and low muzzle velocity weapon. These were loaded with shotgun type grapeshot or canister shot, or else with specialized barshot or chainshot. These later types were intended to damage rigging, while the grapeshot was designed to damage personnel.

Following this example, suggests that mages would be utilized for a few powerful and distributed shots to disrupt enemy personnel or equipment. Instead of a single fireball, the mage would be used for anti-personnel blasts, firing projectiles (or chain lighting) at multiple targets for maximum personnel damage. Alternately, the mage could be used to damage equipment like rigging at sea, or to try to light a boat on fire. The same could be applied to seige equipment.

### Minion

Very similar to the Carronade, this was smaller and designed for use on land. A notable existing one is 'Boston' held by an English Civil War re-enactment society. Boston could carry a three pound ball, but would be used with ~1/2" grapeshot in combat, with an effective range of 250 yds. Looking at the linked pictures, note the large wheels for mobility. Wizards could be moved into position to deliver such devastating grapeshot blows into massed enemy formations.

### Massed arquebusiers

The arquebus had a long range, but low accuracy, and was mostly effective in volley fire. This was the principle behind the Spanish Tercio. As early as Cerignola, the power of massed arquebus protected by pikes was used to repel both cavalry and infantry charges.

Ultimately, a charge doesn't take vary long (men running in mail get tired fast), and an arquebus took up to a minute to reload. A mage could probably replicate the effect of 10 or 100 arquebusiers per shot. Even if they are limited to 3 shots a day, a few mages protected by pikes could be used effectively with Tercio tactics; though they would be at great disadvantage if the battle lasted for more than a few hours.

# Conclusions

The mage would be optimized for wide spread anti-personnel or anti-equipment blows. While mages are squishy, cannons are also easy to put out of service, what with their vulnerable wooden wheels and ~5 squishy operators.

If there are small numbers of mages, they should be deployed like minions or carronades at sea. If there are large numbers of mages, they should be deployed in combined arms tactics with pikemen, simulating the tercio of the early modern period.

• I am not sure of the parallel with cannons. Specifically, I am afraid that the cost to create a cannon and train its crew, is much less than that to train a single mage (the OP says decades). This seems to me that while losing a cannon is costly, losing a mage is catastrophic. – Matthieu M. Aug 24 '18 at 19:41
• @MatthieuM. Note that the training time to create a mage is a pipeline effect. Losing them isn't necessarily more expensive than a cannon when you consider how expensive early cannon were, but the lead-time on replacements is large enough that you basically always must be training replacements at a sizeable fraction of the rate you'll need for fighting a war because otherwise the war will be over before you can adjust your output. This may not be a problem however depending upon the civilian applications of magic available. – Perkins Aug 24 '18 at 20:43
• @Perkins: I disagree. All mages die, at the very least from old age. The rate at which new mages are formed more or less matches the rate at which they retire due to age since the percentage of mages is constant in the population (modulo growth rate). If mages usually serve after training for 20 years and you lose a mage in their first year; you're down one mage for the next 19 years. That is, with cannons you can adjust the output to replace the busted ones; with mages the scarcity of talented recruits is your bottleneck, and losses are irreplaceable. – Matthieu M. Aug 25 '18 at 10:08
• @MatthieuM. There's no genetic component to magic in the world description, so the population of mages is arbitrarily controllable, but with a 20 year lead time. You need only set the training rate to produce enough of a surplus to offset the expected losses if a war breaks out. Do like the English did with archery and make basic magic training mandatory for all citizens so then you only need a much shorter period of time to apply specific military training when you require more mages for the current war. The training time for a mage vs an expert longbow archer isn't much different really. – Perkins Aug 28 '18 at 20:18

Many of the answers here focus on individual battles and tactics, but not so much on strategy, so I'll chip in a few points there.

Firstly, let's consider the cost-effectiveness of your mages:

Your mages require many years or decades of training before they are ready for use. Their rate-of-fire is very slow and modest in potency. And finally, they are squishy (and often elderly) humans, subject to all the usual human foibles and weaknesses.

It's worth noting that in medieval times, any kind of scholarly pursuit was very expensive due to the rarity of books (no printing press, so everything was hand-written). Furthermore, if these mages are unable to use magic effectively until they've had a decade or two of training, that's a decade or two that they are consuming national resources with no return on investment. And if, after completing his training, an aspiring mage goes out to the battlefield and gets killed, or catches any number of deadly medieval diseases whilst on the road, that entire investment of time and resources would be wasted. Also consider that the average life expectancy of medieval Europeans was only about 31 years! Two decades of study would mean that your average mage would only have 3-5 years of useful life, 10-15 years if you're generous.

Simply put, your mages are enormously expensive to produce, aren't useful for very long, and are very fragile. They are the stereotypical Glass Cannons, so expensive and so fragile, in fact, that I'm not sure any sensible commander would dare place them on the front lines unless they were in dire straits. Wars are just as often won by economics as they are by military strength.

Secondly, let's consider the three greatest challenges in pre-industrial warfare:

Before radio, communication on the battlefield and with the military's senior leadership was slow, imprecise, and unreliable. In battle, army units were controlled via music (horns or drums), smoke signals, or flags. A good way to disable an enemy force was to take out their flag-bearer/horn-blower, and then isolate and demolish the individual units in the ensuing confusion.

Reporting the movements of enemy forces to, or receiving orders from, the senior leadership sitting in a nearby town or the nation's capital required sending mounted couriers or trained birds with tiny scrolls, which could take days or weeks and were vulnerable to getting lost or intercepted. You can have the mightiest army in the world and still lose a war because your opponent could outmaneuver you. Case in point: the Roman empire.

This might be the single most-useful role for mages. You've ruled out instantaneous communications in your magic system, but not teleportation or near-instantaneous communication. Consider, instead of sending a courier across the river through the haunted forest around the enemy camp up the mountain and into the valley, you could just "beam him up" to wherever the bigwigs are sitting? Or if you could set up a series of communications posts, each with a couple of mages, who could manipulate light, smoke, cloud, whatever, to relay messages from tower to tower? Suddenly you would be able to coordinate your entire army, everywhere in your empire, in minutes or hours rather than weeks, and without any risk to your valuable mages.

Partially as a result of lack of communication, it was also very difficult for local battle commanders to know where the enemy's forces were, where the local terrain was beneficial or harmful, and where valuable targets were located. To gain this knowledge, they would have to deploy scouts (mounted or on foot), who would travel ahead of the army and (hopefully) report back. But scouts could be easily captured or killed, especially if not riding a horse.

Here, again, teleportation would be a useful skill for a scout. Even the ability to conjure a brief distraction or camouflage one's self would greatly increase the chance of survival and escape for a scout. But, this would put the mages in a fair amount of danger, so it might not be cost-effective.

As Frederick the Great famously said: an army marches on its stomach. Providing food and equipment to an army -especially one operating in hostile territory- is probably the single greatest challenge to every armed conflict in history. Not only do you have to move a lot of stuff, but you have to move it over long distances to a target that is itself always moving. No matter how big and powerful your weapons, your troops will all quickly die or desert if you can't keep them fed and clothed -and the same is true of your adversary. Supply lines were a fabulously attractive target, not only because you could deny supplies to your foe, but you could also make use of them for yourself if you captured them!

Attacking enemy supply lines might be a viable offensive use for mages. Mages are like hand-cannons in your world: modestly powerful but slow to reload, basically lighter, more mobile artillery. Mounted on horseback, a team of mages could suddenly descend on an enemy supply caravan, blow up all the wagons before the defenders knew what was happening, and retreat at a gallop. Hit-and-run tactics would be the most effective and the least risky, and it wouldn't take many lost wagons to incapacitate an army. Of course, your enemy would try the same tricks on you, whilst also adding mages to the caravan escort to repel your attacks, and you would do the same, and so on...

Finally, let's talk about direct front-line combat. As I said above, your mages are very much like hand-cannoneers in the early days of gunpowder. Look at the tactics used by the Hussites and the Chinese; typically, the gunners took an artillery or armor-piercing role in the army, replacing ballistas and trebuchets, and often working in tandem with conventional troops.

One such application that comes to my mind would be embedding a couple mages in a Roman Phalanx formation. A phalanx is a slow-moving but nigh-impenetrable wall of shields and spears. Cavalry, infantry, archers, none of them could really do much to hurt a phalanx unless they could get behind it. A mage inside such a formation would be very safe and would effectively function like a cannon: periodically emerging from behind the shield wall to wipe out approaching infantry or cavalry, tear down fortifications, or repel enemy siege engine fire before retreating back inside. A couple mages in the rear could very effectively counter any attempt to flank the formation, eliminating the greatest weakness of the formation. Basically, you'd have the medieval version of a tank.

Another thing to consider is how your mages use their power. Throwing fireballs into a crowd of soldiers makes for a cool kaboom, but you could just as easily incapacitate those same troops by blinding them with focused light, or deafening them by setting of a shockwave in the middle of their formation -and doing so would likely be more energy-efficient than a fireball. In fact, a light-based attack is inherently unblockable because, unless your troops all have sunglasses, defensively filtering or blocking their eyes would have just as detrimental effect as the attack itself.

• Re: Pre-modern life expectancy: most of the loss of life was in infancy/childhood. From your link: "However, by the time the 13th-Century boy had reached 20 he could hope to live to 45, and if he made it to 30 he had a good chance of making it into his fifties." So that adds several decades to expected life of someone who matriculates to college. – Daniel R. Collins Aug 25 '18 at 14:54
• True enough, though I'd call attention to the "hope to" and "had a good chance" qualifiers on that statement. It's also important to note that mage training would likely have to begin at an early age (probably around 10 or 12) to ensure a longer useful life, but per a related life expectancy reference: "Once children reached the age of 10, their life expectancy was 32.2 years, and for those who survived to 25, the remaining life expectancy was 23.3 years." So the threat of mortality would still be high in the early years of training. academic.oup.com/ije/article/34/6/1435/707557 – MikeB Aug 25 '18 at 22:09

There are three roles that I see for mages under these circumstances:

Artillery: The trick is to get them close enough to the enemy without getting shot. Have they need to hide their staves as they approach in their units. Maybe the units can use shield wall tactics to protect the mages. Then ripple fire into the mid and back of the units they are facing. This will make it much easier to punch through the enemy unit. Then the mages are done unless the battle takes far longer than they usually do.

Terrain Control: Before battle (or during if you want to take the risk), make ditches, choke points and, maybe, pits to slow down enemy approach. That will give enough time to blast the enemy with artillery magic. This can be used offensively too to smooth the ground for a charge.

Utility: Make roads, clean water, till a field, build a fort, heal the injured and anything else you can think of. Anything that helps the kingdom increases its fighting strength.

Combo Artillery and Terrain Control: Blow the earth in front of a charging unit so the dirt and rock flies into the enemy. This causes wounds from the rock, blinds them during their charge, may bury a few, cause the back ranks to bump into the front ranks, and creates a ditch for the blinded/wounded/pushed enemy to fall into.

Before I get to the meat of my answer, let's keep a few things in mind.

Castles as we know them wouldn't exist Well, that's a bit hyperbolic, there probably would be some fortifications somewhere, but if there is a widespread group of people who can simply walk up to your hideously expensive, painstakingly built stone fort and wish big holes in it, you wouldn't build them.

I imagine most armies/towns would simply use a ditch/berm with maybe a log palisade, because anything else would bankrupt you.

Most people didn't die on the fighting line Most people who died in medieval warfare did so from disease and/or starvation.

Most people who died in medieval battles did so after one side broke. Battles would generally consist of maneuvering until one side felt they had an advantage, then they would commit. If they were right, the other side usually broke and ran - if they were wrong they usually lost some guys and retreated, or were counterattacked and broke themselves.

Then the cavalry did it's job, which contrary to popular movies was not to charge headlong into solid blocks of enemy troops. They harried the fleeing enemy because horses can outrun people over short distances. That's how you end up with those seemingly ridiculous 200 vs 6500 casualty accounts.

Okay, so answer time -

Strategically

These guys make siege warfare an irrelevance. Look up historical examples like https://en.wikipedia.org/wiki/Fall_of_Constantinople#Siege for the sheer scale of what medieval besiegers had to bring to take down a wall. In your world those walls probably wouldn't exist, but still.

So there would by the nature of things be more field engagements.

Tactically First, there is no way these guys would operate in a vacuum. Just like Knights had a whole team of fellas helping them, so would these guys. I imagine at least five bodyguards or shieldbearers. Any hit that would go to the mage, be it mundane or magical, these guys take. They are paid exceptionally well for the risk, it's a veteran's job. A mage also would probably have a couple of understudies/pages/messengers to handle their personal effects and keep them in communication with higher ups and their peers. The severely limited number of spells means coordination is more important than your standard medieval army in our world.

The mages would be your most valuable military asset, because they are adaptable force multipliers. They can use different spells in different circumstances, whereas a cannon is just a cannon.

Shock cavalry would be less useful in your world, if there are guys who can make fire happen out of nowhere. Horses don't do fire, even well trained warhorses aren't as stupid as people.

You need to hide your number of mages. If the enemy knows how many mages you have they are either going to run away until they can pick them off, or just steamroll you depending on who has more. If spells can more or less be countered by a similar power-level mage, the side that ends up with six or seven extra fireballs is probably going to win.

Mages should ideally be used like tanks - concentrate as much fire and fury into an area as possible to break formations. Armor up your mages, have your best infantry assembled, wait until the enemy seems to have expended most of their spells and charge the weakest section of the enemy line. Right before you hit, unleash four fifths of your remaining spells in the most destructive manner possible. Shock and awe.

I imagine most battles between roughly even forces would end up being a series of feints or maneuvers attempting to draw out enemy mages and waste their spells before one side just goes in.

The end point of all of this of course is that this guy

Would kill everyone even harder than in our world. They would outrange the mages and everyone would be depending on the mages for battle winning miracles that just wouldn't happen against a highly mobile logistics independent force. Without forts, warfare would be more mobile, and no one wins mobile warfare like steppe nomad horse archers.

And then someday someone would invent a rifled musket and mages would be relegated to entertaining the troops or digging ditches.

Warfare come in all shape and size, so your mages can affect the tactic and strategy in many way. Your magic is not strong enough to cause any drastic change in warfare, but it can make some aspect of war become more effective. Here i'll try to break it down to different levels of warfare:

L1. Personal combat: Your mages are strong, but not strong enough. Pre-firearms battle tend to be quick and exhausting, so your mages only have one shot per battle most of the time. A small squad of normal soldier could be more efficient in my opinion.

L2.Battle Since the damage is not that impressive, your mages's role in battle wont be damage-dealer, but rather a support role. One notable use for your mages is to disrupt enemy formation. A few ditchs appear out of nowhere could greatly reduce the momentum of a calvary charge, and a fireball in the shield wall could leave a big gap for infantry to exploit.

L3.Campaign Your mages will be great tool for siege (which play a major part in medieval warfare), since they are more precise and creative than your trebuchet. He could, for examples, cover all the "kill-hole?" in the battlement, or hex some random enemy with cholera that could quickly infect the entire castle...

L4.Pre-war Preparation And here your mages truly shine. Send them to enemy's main city or region, and then start a plague or something..

In short, warfare will still be familar to us, but also quite different form history. War will be more deadly (and thus less frequent), castle will lose some of its importance (and open battle more common), and the battlefield will be more chaostics and have less formation.

I can only think about 3 kinds of uses for a mage:

• Manpower.
• Support/utility role.
• Triumph card.

## Triumph Card

As you said, each 1.000 thousand soldier there are around a dozen (12) of mages.
I think they could be used as a perfect triumph card. 12 mages are able to cast 12 spells per hour for 3 hours.

• Knowing that the average fireball only has 5 meters impact diameter it may be a good option. I don't know the number of soldiers per squared-meter of battlefield but if it were 1 every 2 meters, your mages would be able to kill $\frac{5^2\times12\times3}{2}=450\text{ per day}$, if the battle only lasted for an hour it would be $150\text{ soldiers}$.
Mages are humans, which mean they are small, light and self-propelled, not like a catapult or trebuchet. Even they can hide as normal soldiers or civilians. Imagine a situation where a few mages secretly get close to the city wall, and together they break the main door or make a hole in it to let soldiers invade it easier.
• Imagine that your enemy (or you) are retreating from the battlefield. With several mages, they could cast an earth wall from the surrounding ground in order to close the enemy retreat line or buying you time to escape while the enemies get stuck by it. You could also divide the enemy armies with walls.
• Imagine a battle with a hill and a plain zone:
• If your army is on the hill you could:
• Throw huge casted stone balls (or adobe/mudbrick balls) through the step of the hill. With the help of gravity, these balls can kill a lot of enemies.
• Flood the valley/plain with a strong stream of water (cast from the deepness of earth). Enemies with heavy armour will sink while the other will have a difficult time.
• Cast a very bright light towards your enemy in order to blind it and difficult the fight.
• If your enemy is on the hill (or there is a plain enemy zone, a hill and then a plain ally zone) you could:
• Move the earth of the hill causing an avalanche of earth violently killing and crushing enemies on or under the avalanche. (Warning: be careful casting the avalanche, it must go forward you and not towards you... otherwise, it can a bad idea dangerous).

If you don't like to use them as artillery, siege or in a so violent way, you could also think about other alternatives like:

• Poison a water well, farm field or the supply foods of your enemy with magic. (Mages could get infiltrated as spies in the enemy lines).
• Simulate the illusion of a bigger army to scare the enemy.
• Close enemy supply path.
• Summon mist or fog to difficult enemy visibility (maybe it can also be toxic).

# Support/Utility Role

Maybe mages can't/aren't able/don't want to kill people so violently. It doesn't matter, they can still be useful.

• Healing magic. You didn't say mages can't use healing magic. They could heal/cure (or just stabilize) around 3 VIPs per day with spells.
• ¿Teleport VIPs? (You said there isn't communication spells, so not sure if this could be done).
• Make new roads and transport lines. They can increase the efficiency of your supply line.
• Build tends from your army quickly with magic.
• Fix armours, catapults, walls with repairing magic.
• Fast communication using lights and signals in the sky.
• Dry streams and rives to move soldiers, or even flood fields to cut the path for enemies.

# Manpower

With magic a lot of stuff can be done easily:

• Work in farm fields: with magic you can harvest plants, increase their speed, fertilize grounds, or even build irrigation zones with water streams.
• Work as a doctor using healing magic or helping indirectly (cauterize wounds, pasteurized surgeon tools, fix bones misplaced, etc).
• Work building: telekinetic magic can help to cut a tree, making planks from logs and put them in the correct place to build a house, a palisade or even a stone wall.

It's kind of limited only by your imagination (or the imagination of the characters, whichever is lower) - but basically the old adage applies here, that magic is no different from "sufficiently advanced technology".

In other words, there are real inventions (i.e. weapons) that mimic how your mages work - a 5m fireball? Not much different from a grenade. Breaking a wall without a battering ram is a bit like a cannon. I think you'll find a lot of the ideas you could think of have modern-day equivalents using technology.

I would look to how these inventions have affected warfare and adapt to fit your scenario, though it would seem your mages would have the equivalent powers only highly limited, so you'd have to consider what it would be like if, for example, cannon balls were in extremely short supply.

And remember, if you have mages that can do things that normal medieval armies could not, then the enemy would change their tactics to suit. e.g. if you have a mage that can break a wall, the enemy may adapt by building a fortress with multiple walls, or thicker walls (if thickness makes it more difficult for the spell to work), etc.

Teamwork!

Assuming you have a dozen mages in your army, the trick would be to get all of them to work in unison to use their limited spells as effectively as possible.

Your telepath mages won't be able to keep a constant line of comunication, but they could be used to send urgent messages, think how useful it would be to warn a city from an approaching army or even to help relay position and status from different parts of the army as they march.

Shield/defensive Mages would be needed to keep your general and other important figures from being cursed by the enemy, they would also be needed to move your offensive mages in position.

Offensive Mages will probably be the glory boys of your army, they will be the rockstars that gets all the glory, burning away enemies troops, cracking walls, cursing enemies, and zapping supplies. But! They will need the constant support of telepaths, fliers, and support mages to keep them alive.

So, the idea is for mages to form small groups of individuals, each specialized in some different spell and trained to support each other or even combine their spells to strike hard and fast, retreating for security before the enemy could counter-attack.

A lot of things, but you basically make your mages an assassin with the ability to shot poison arrow only 3 times a day while it take him one hour to prepare said poison between shots. So fireball generals on battlefields. Sneak into castles using illusion and silently kill people by shattering their hearts. And as with assassins, they are great at killing and sneaking but you don't make a platoon out of them to send them to battle.

The battering ram usage is pointless as you need to have an experienced older mage. Making a ram requires some trees, few hours and inexperienced crew. Using fireballs on enemy soldiers is a waste of magic. Archers do that far better and can shot much more arrows per battle. And such fireball would work as good at trebuchet launching, well, fireballs. While again, trebuchet have much higher shot per hour ratio.

Maybe some guerrilla use. A mage disguised as regular merchant walk on the bridge just minutes before some important figure. The bridge collapse and nobleman die. A mine is unable to mine resources as trolleys brake. and of course, the couriers bearing important news die in their sleep.

• How are you going to sneak anywhere with an illusion that lasts only a few seconds? They can only cast 3 spells a day, one hour between spells, and each spell is instantaneous. No lasting effects. – user54563 Aug 24 '18 at 13:44
• Using it wisely. You don't cast illusion before embarking on a journey. anyone would notice walking broom. But when you're hiding and somebody open a broom lock he see brooms, not a guy with staff in his hand. So he close the doors. Bam, spell casted, discovery averted. – SZCZERZO KŁY Aug 24 '18 at 13:50
• Provided that the guard doesn't look for more than a few seconds, or that nobody looks more than three times. How is anyone going to get through a fortified castle filled with guards with only four seconds of illusion, while carrying a large, easily identifiable staff? A totally mundane assassin hiding a poisoned knife would have much a better shot. – user54563 Aug 24 '18 at 13:57
• You disguise your staff as broom and yourself as a street sweeper. When passing a guard near back entrance you cast illusion of almost naked women in the opposite direction and when guard looks the other way you sneak in. – SZCZERZO KŁY Aug 24 '18 at 14:09

Enchanted catapults.

Mages hang back and enchant the catapults (or the ammo/rock). The effect makes the weapon explosive. Catapults have a long range, magic ones go even further. At 3 shots per mage, you have a decent amount of shots to do maximum damage early on in a battle.

This turns them into the first artillery.

Later on, enchanted cannons. Same effect, more power, more range. Every rich ship might have a mage to sink an opposing ship in a single enchanted canon shot.

You can think of many other support roles too. They could be medics for important officers and leaders. They could handle battlefield long range communications (sky flares, etc).

Warfare isn't just killing. Logistics and tactics are equally important. A mage could create food and water for an army. Or they could burn a map of enemy positions into the ground for all to see. There is limitless possibilities for non combat roles.