In my story, there would eventually be a final battle between a modern/high tech army from Earth and a coalition from another world. What are ways that the coalition can gain victory? Given that they possess a limited range of magic, a deep understanding of the modern army, enormous physical strength and overwhelming number?

This is my first question, so if I need to add or edit anything, please let me know.

Edit 1: Thanks for the suggestions for edit everyone! You guys have been really helpful despite the lack of information! Some members asked for the weapons and resources on both sides, and others of the likes for better answers. I will list them below

Edit 2: I've noticed that the question has been put "on hold" again instead of "Closed". It might just be an error, but in case it's not, I will change some stuff to avoid misunderstandings. One member pointed out that this question is too story-based, which I think might be true. Though I only wanted to know common strategies that can be used given the situation, which I will only use as reference, no more no less.

The Earthers know that the coalition is coming within two months, through portals which can be open anywhere at anytime, therefore they've been preparing to drive off the invasion (Evacuating civilians, fortifying buildings, etc.)

The coalition is well aware of how powerful the Earth army is, therefore, they don't wish for a long-term war (due to how difficult it is to transport food/water supply, troop transportation, etc). Earth had tried invade their planet before in the past, and they failed due to underestimating the coalition. And the coalition, though surprised of the Earth's god-like power, was able to stop the invasion while suffering heavy causalities. This is how they know of Earth's weapons and history, they also attained more information after interrogating Earth prisoners, such as how modern cities/buildings are very different from theirs and can be fortified in many ways, ETC.

Fighting: Fighting will take place mainly on military bases and cities, and where most evacuees will stay, the coalition army wants take civilians hostages to deter actions from the enemy. They will mostly ignore countrysides or jungles, where they assume are not important (can be changed).


For the Earth: every single type of weapons in modern 21st century.

  • Manpower: more than 300,000,000 strong, including regular, reserve & paramilitary forces, This is the result of every countries on Earth uniting to fight

  • Resources: Everything they have available, at this time, crops start to decline due to the planet dying out, and they only have 4 years of food supplies left if they use it all for this war, though water is still plentiful. So rationing will be really strict and might spark civil conflicts within the ranks or cities (The coalition isn't aware of this.)

For the coalition

  • Curved swords, spears, catapults, ballista (can pierce through tanks, Mangonel.

    • explosive crossbows: high accuracy, when not installed with explosive they can pierce through standard US body armor

    • cannon (something like a Madsen 20mm Cannon, though with longer reloading times) Their latest weapons, constructed based on their knowledge of the enemy. These are also very rare, as there are only about 300 of them at the time of the invasion

  • Armor: Leather (material can be changed if suggested) armor made of a giant species' skin on their planet, thick and strong to protect soldiers from standard US rifles.

  • Shields: Scutum-like Shields and Mantlet, both made of materials strong enough to deflect 50 cal and below

  • Calvary: Riders possess Bull-like creatures that can run at 150km/h at maximum speed, can destroy/crash through brick/concrete walls

  • Manpower: more than 900,000,000 strong, well-trained.

    • Resources: Plentiful in everything

    • Physical power: one individual soldier can be as strong as 10 professional human soldiers, due to the conditions of their planet

  • Magic: Summoning spirits that are only visible to the caster's eyes, these spirits can go through any physical barriers, the spirit can interact with any objects, and the maximum distance the spirits can be away from the casters are about 600 meters. The only way to get rid of them is to locate and kill the casters.

  • Communication: Flag, sound, smoke, light, rider signals to get messages across

  • Important notes: The coalition army looks exactly like humans, only with larger size (3-4 heads taller than average humans). And when they travel through portals to reach Earth, these portals are only 20 meters wide each, so it takes lots of time to bring all soldiers to the other side.

As of right now, I am open to any suggestions about various tactics that can be used regarding fighting in cities, either full-on frontal assaults or guerilla.

  • $\begingroup$ I'm afraid that unless they have some magical way to mitigate the huge technical difference, the medieval army would get slaughtered without the slightest chance. $\endgroup$ – Hyfnae Sep 28 '18 at 8:16
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    $\begingroup$ 'limited range of magic' is far too vague. What exactly can they do, what are their limitations? ---- Also: 'overwhelming' is the answer. If one force is overwhelming, the other is overwhelmed, so your medieval army is set for victory. Also: what is their beachhead, does the earth know when, where and how the horde is arriving?. Also: Is the earth united against the horde, or are there countries that are in known, or suspected, cahoots? (even a suspected alliance will weaken the earths response, as everyone is watching their backs). Also: The aliens: Food? Sleep? Flying? Warm? $\endgroup$ – bukwyrm Sep 28 '18 at 8:16
  • $\begingroup$ Which of the two is in its own times? the medieval or the modern army? $\endgroup$ – L.Dutch - Reinstate Monica Sep 28 '18 at 8:17
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    $\begingroup$ You need to give a lot more information, I'm not even start to list all that you have to include to explain the initial condition better. You also have to give some restrictions on what you want to happen. For example, one army could make a mistake and ensure up in a horrible situation, e.g. without food and water in a desert with nothing left to do but concede defeat. Or they might be hit by a plague. You could find allies or bribe soldiers to revolt. So many options... most likely not all of them within the scope of your story. $\endgroup$ – Raditz_35 Sep 28 '18 at 8:39
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    $\begingroup$ (1) Where are they fighting? On Earth or on their faraway world? (2) What does "overhelming" mean exactly? 10 to 1, 100 to 1, 1000 to 1? (3) A "battle" won't work; a modern-ish army (say, from the beginning of the 20th century) would slaughter a medieval army in a set-piece battle, even if outnumbered 1000 to 1. ("Whatever happens, we have got the Maxim gun and they have not.") (4) "Limited" magic means unlimited possibilities. Please describe the actual magic. (5) A medieval military cannot have a "deep understanding" of a modern army. They don't even have words for modern concepts. $\endgroup$ – AlexP Sep 28 '18 at 8:52

The way it is done in real life.

No magic or super strength needed, although "a deep understanding of the modern army" is paramount.

They would never ever engage this modern army in a full frontal assault. In stead they would wage guerilla warfare for as long as it takes to wear out their opponent. They will take a page from the Vietcong book of defeating a superior force and basically act like an army of organized sadistic serial killers. They will poison or destroy food supplies, set traps, use tortured and dying prisoners as bait for said traps. They would destroy any and all soft target they can, and try to infiltrate the enemy wherever possible to engage in sabotage and suicide bombings. We've all seen this happen. They would not aim to defeat the enemy directly, but instead do everything they can to destroy morale and public support in the enemies civilian population.

Changes are, they'll win.

  • $\begingroup$ Wars are incredibly expensive, so if the population on the side of the modern army is not 100% committed and supporting it, than it's not a matter of winning anymore, they just have to sustain the war long enough until the modern army money runs out. Besides US, China and other big countries, almost no other country can sustain a war for too long. $\endgroup$ – Lupino Sep 28 '18 at 8:44
  • $\begingroup$ I agree with the first sentence, however the Vietcong and the Taliban have made it painfully clear that the second is debatable. $\endgroup$ – Douwe Sep 28 '18 at 8:47
  • $\begingroup$ It's a maxim of the history of "small wars" - irregular forces will always defeat a professional army in a protracted engagement. The American revolution only started to make inroads when George Washington stopped trying to force his troops to act like professional British soldiers. $\endgroup$ – pojo-guy Sep 28 '18 at 11:06
  • $\begingroup$ @pojo-guy I think you've gotten it backwards. At Valley Forge, Washington had von Steuben train his army to be the same sort of troops that the English had. Irregular forces lose against regulars, unless they have some strong advantages. (Your statement might be partly true, since if the irregulars can make it a protracted engagement, rather than being wiped out fast, they do have a considerable advantage to start with.) $\endgroup$ – David Thornley Sep 28 '18 at 15:43
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    $\begingroup$ @JBH Forget OP, I'm writing the script already. It's called "Gangsta's in Hell" (tagline: I don't think we in the hood no more). I'm hoping to cast Ice Cube for the lead ;) $\endgroup$ – Douwe Sep 29 '18 at 15:58

It's probably not the answer you're looking for, but here's my guess :

By trying as hard as they can to upgrade their warfare technologies

You said the medieval army has a

deep understanding of the modern army

With that in mind I think the best chance they have is to copy and try to recreate whatever they can from the modern army.

On the same idea, to get on par with the modern army technology wise, try to steal weapons or even vehicles to study them and use them against their creators.

With good engineers and a lot of study material (you could steal vehicles/weapons pretty easily by attacking weak outposts that are not well protected because of weak geographic value), your medieval coalition should be able to upgrade their warfare technology, which would even the odds.

The main limitation of this plan would be very complex vehicles/weapons, airplanes comes to mind. They probably would never have time to teach people to become pilots or to recreate a plane during the war. Meaning that they'll never be even close to be on par with the modern army technology-wise.

  • $\begingroup$ This was the answer I was looking for. Cheers. $\endgroup$ – JBH Sep 28 '18 at 17:40

I'm going to leave Magic out of this answer as without more knowledge of how your magic system works its difficult to factor it in

Historical examples

Obviously some of these have a greater disparity in Weapons Technology than others but the common themes are still there.

Zulu's vs British

The Zulus, armed with leather Shields and shortened fighting spears, using local knowledge of terrain, a deep knowledge of Imperialist British fighting Tactics, superior numbers, speed and surprise, managed to win a couple of battles with the British who were fighting with breach loaded rifles cannons etc and were well trained in fighting as a unit. the Zulus lost the war eventually, however the fact thy met the British face to face on equal footing can be argued to be a leading cause

One important factor was that the Zulu's captured a lot of British weapons and used them against the British, your forces would probably want to do the same with weapons that can be figured out


I also highly recommend watching the film Zulu, not for research, its just an amazing film!!!

Vietcong vs US

This has been explained by others but its importance is the same, they beat a superior force by using guerrilla tactics, however they were also using firearms, they may not have had the air power or tanks to match the US but on foot, the only disparity was training and numbers

Taliban vs Coalition forces

This has also been explained by others answers, however consider that the Vietcong were hiding in the jungles and tunnels, armed with firearms fighting against foot soldiers with firearms with air power to back them up if needed but rarely rapidly, whereas the Taliban hiding in public, they still use firearms but the Coalition forces have improved drastically since the Vietnam war.

This is just opinion but i think is the reason that Afghanistan was not lost (notice i haven't said won, just not lost) by the coalition forces as the Russians did, that significant different in warfare finally tipped the balance compared to Vietnam and Russia

What can we draw from these examples

The major important factor to consider in this is each example deals with the Advanced Military Force fighting on foreign soil. this means transporting troops and equipment is costly and difficult to do in huge numbers and without detailed local knowledge of the area.

Satellite imagery can get you so far but it lacks the ability to show how well that group of rocks could be used as a firing position,

Some may disagree about the small numbers due to logistics, but consider: the US deployed at its peak 100,000 troops to Afghanistan, not all of these are fighting soldiers that go face to face with the Taliban, most in fact were support personnel. (i'm not taking anything away from those men and woman, they all served and performed their duties) whereas if another Nation attacked the US on US soil, they have over a million servicemen and women that would be in the fight at the same time in their own ways. and that doesn't even include the number of reserve personnel, veterans and civilians that would be involved in one way or another,

the Primitive (by comparison) Military Force has larger numbers, local knowledge, and knows how the AMF fights, all it comes down to at that point is how much numbers they have, how spread out is the front, and how long is the war expected to take

The Second Really important factor

It'll be over by Christmas??? maybe not

Over confidence is a huge factor in all asymmetric combat, historically when an advanced force is defeated in a battle, it is down to underestimating the more primitive enemy

What tactics would be used

Guerrilla Tactics are a must

Fight it on home turf with home knowledge,

Hit supply lines when possible

Use a lot of diversionary tactics, make it look like the PMF is massing in one place and then hit the supply lines in another

Steal!!! if the PMF can get hold of firearms then use them

And most importantly... learn to be careful of the little black dots in the sky that make fire appear!!!!!!!!!!! if they see these, run and hide!

  • $\begingroup$ The Zulus won one battle against the British, the battle of Isandhlwana. The British army was badly deployed, and ran low on ammunition. Further battles went to the British, including the battle of Rorke's Drift in which a few British soldiers repelled a much larger number of Zulus (and, yes, Zulu is a great movie). The battle of Ulundi was much the same situation as Isandhlwana, except that the British knew what to expect, and shot the Zulus to pieces. $\endgroup$ – David Thornley Sep 28 '18 at 15:48
  • $\begingroup$ The Zulus won the battle of Isandhlwana on January 22 1879, yes a second Zulu force were then defeated at Rourke's Drift, but the Zulus also won a battle at Hlobane on March 28. obviously i was wrong to put "several" and should have put "a couple" and will edit this now. $\endgroup$ – Blade Wraith Oct 1 '18 at 8:20

The way it is done in Starwars.

Bonus points if they are cuddly, teddy bear like creatures.

They will use their primitive slings to tackle the enemies walkers. They will use the terrain to their advantage, and attack from the trees or from holes in the ground when the enemy is right on top of them.

They will immediately use every gun, blaster, tank or walker they capture to wreak havoc on their enemy. They will use their elderly and children to swarm on straggling enemy soldiers. If one rock thrown does not do the trick, they will throw a hundred, or a thousand. They will trick their enemy in believing they're harmless, before showing them that an arrow or spear can be just as deadly as a bullet.

Lastly, they will aide a small bunch of resistance fighters in taking out the enemies power supply and call it a day. Party in the treetops everyone!

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    $\begingroup$ haha. I didn't thought I would live to see someone using the Endor battle as a good example for anything. Well done! $\endgroup$ – Lupino Sep 28 '18 at 9:55
  • $\begingroup$ The Imperials on Endor relied on attacks by those hideously impractical chicken walkers. A WWII-era army would have had tanks that would shrug off anything the teddy bears could use. $\endgroup$ – David Thornley Sep 28 '18 at 15:40
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    $\begingroup$ Do you know heavy those two tree trunks would have had to be, and how fast they had to be travelling, to crush that walker? The battle is a great example of "how it can be done" so long as you ignore the fact that it's a great example of suspending reality to tell a fun story. $\endgroup$ – JBH Sep 28 '18 at 17:39

First step is diplomacy. Your men dont like dying and the lionshare of your enemies does not want to outright kill, and will instead try to look busy by shooting anywhere but at the enemy. Perhaps you have materials and goods to offer to the techies? Or ground that you can sell in trade for education and technology?

Second step is to target their fuel.

With the exception of a nuclear exchange, modern warfare on a large scale revolves for an immense part on how much fuel you have to drive your vehicles and aircraft and use the gadgets they carry. By targeting the fuel you might not stop a tank from being manually aimed and fired, but it will be far more limited. You also wont have to deal with attack helicopters, aircraft and ships. Even so, dealing with small arms while you have bows and such is going to Hurt.

To do this, capture and destroy their oil reserves, refineries, supply lines and production.

Depending on your magic system, you could use it against fuel and explosives. Imagine being able to create and electrical/fire spark inside a fuel tank, or the ammo storage of a tank, the grenades or ammo clips of an enemy soldier? Or imagine you can spoil fuel, causing engines to need heavy maintenance while the vehicle itself stalls. Or imagine if you can increase the explosive power of anything, causing too high stresses on small and large Guns alike.

If you do get caught in warfare and cant target the fuel, use cities. I'm assuming the techies arent on a genocide campaign or the medieval guys are practically dead. Inside a city you can more easily ambush, and the advantage of a gun over a sword wielding maniac in CQC is a lot less.

Someone is probably going to cite the Africans that beat the English in several battles, but the English underestimated the battle prowess and it was more a problem with the English battle doctrine they (failed to) use(d).


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