Modern military equipment in a fantasy world

Question

So we've (re)discovered a portal to a magical realm akin to 12th century Europe but with magic. We have giants, trolls, dwarves, wizards, etc. One faction calls upon our aid. Invoking a supposed alliance our ancestors agreed upon.

We accept and send a reconnaissance force made up from our modern militaries of about 300 men. They're to link up with the faction's own military. It as well as our enemies are largely made up of a noble caste of elite warriors and a larger group of conscripted peasants. Most of them are of giant heritage and over 9 feet tall.

So we're expected to be on missions for days on end with routine skirmishes. Resupplies can be days if not weeks away. Contact with Earth will be even more rare. Travel to Earth can be done through magical wooden ships, each should be able to carry a 100 men with gear. They won't support mechanized armor.

To clarify: A trip through the portal requires the usage of what's for all intent and purposes an oversize longboat. It won't support the localized weight of say an APC. That's ignoring the restrictions in fuel by having to remain on it's own for weeks on end.

So my question, what kind of weapon would a modern military equip their soldiers with if they're expected to fight a more primitive force that relies on spears, shields and bows but has a significant physical advantage? Especially as supplies like ammunition would be rare and it will take several engagements between resupplies.

Some expected enemies:

• Giant domesticated boars, as big as a wisent.
• Giants of 9 feet tall armed with 12th century gear like spears and maille armor.
• Giant cavalry similar to a norman knight on equally large horses.
• Humans with crossbows as well as shield walls with spears and axes.
• Wolves large enough to hunt the above boars.

Answer 1

Modern defense using Western (NATO) weapons:

Bad news for the troll-warriors and their slaves: We've practiced defensive warfare for centuries, and it's brutal.

At 3000m, a rain of 60mm mortars devastate their formation, spotted by hidden observers and directed by radio or field telephone. No large formations of conscripts after that - the smart ones just deserted.

At 2000m, the warriors enter the zone cleared by fire and chainsaw - limited cover and even easier spotting for the rain of mortars. Being 9-ft tall won't help and chain-mail armor won't help - red-hot, razor-sharp mortar shrapnel will kill and maim throngs of armored giants just like everybody else.

At 800m, the warriors are in aimed-fire range of Light Machine Guns. If they start running now, without pausing, the surviving warriors will reach the defensive position in about three-four minutes...under murderous, aimed machine-gun fire the entire time. The kind of fire that swallowed entire battalions without a hiccup in WWI.

At about 100-150m, the first warriors reach the razor-wire obstacles, which stops them for another minute just outside arrow range, but well within M4 Carbine range. Inside the wire, they start stepping on the tripwires - mines, fougasses, etc. Now the few surviving archers can release a hail of arrows...which fall harmlessly on top of well-prepared fighting positions with overhead cover.

At 25m, the warriors are within grenade and pistol range. But it's over by then. Many thousands of attackers are dead, maimed, or fleeing, and the 100-soldier company of defenders is repairing their lightly-tested defenses and thinking about lunch.

And that's if we cared about the political repercussions. If not, we could use gas mortars and simply suffocate the entire formation...then infect the few, feeble survivors with smallpox before letting them go home to spread rumors of our terrifying power (and spread smallpox) before dying horribly. Let the mountains of their dead soldiers and the smoke from entire provinces of diseased corpses be our heralds to the enemy lords: We don't play at war.

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Modern attack using NATO weapons:

Wagonloads of mortars arrive at the new assault position 3000m from the target, and the attackers simply keep dropping them on the target until the target's not relevant anymore. If the defenders try a sortie or spoiling attack against the assault position, then see above.

The final infantry assault, if needed, should be done by the more numerous local allies supported by modern weapons teams. Grenade launchers are particularly useful support weapons here. Night Vision Devices can make night attacks safer and more secure than daylight attacks.

Again, that assumes that we wouldn't simply gas the target.

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Old-Tyme Logistics for modern weapons:

A single good old horse/ox-drawn Conestoga Wagon can carry up to 6 tons of supplies.

Those machine gun and rifle rounds weigh about 12 grams each, so 100,000 rounds would weigh about (let's round up for packaging) 1.5 tons. 60mm mortars weight about 1.1kg each, so one wagon can carry about 900 rounds.

So for one company of infantry, you're looking at about 4-6 wagonloads of ammo, food, and other supplies to get them to an objective and through one battle to secure that objective. Depending upon the roads, wagons during the US Civil War moved 10-15 miles/day (20km/day).

NATO also has practiced expeditionary warfare for generations, is well practiced in how to set up (and defend) supply routes and bases, and regularly rehearses how to keep forward units well-supplied during both offensive and defensive operations. This means moving large amounts of supplies (more than soldiers) at every opportunity to resupply from modern Earth.

Note that the USA alone could easily field well over one hundred of such decisive army-destroying infantry companies without needing to retrain artillery or armor companies, nor call up the National Guard (which is even larger), nor allies. It's an apocalypse for those giants.

Answer 2

Look at this The Telegraph article and scroll down to the Falklands entry. Dump the NBC gear and carry more food, ammo, and electronics plus batteries instead.

• Modern radios, night vision gear, light drones, and similar gear. They will make quite a difference.
• A modern military would find it difficult or impossible not to bring rifles. That's what they're trained with, and even if a rifle needs ammunition it is much more lethal than any bow.
  • Each rifleman with a 5.56mm assault rifle could carry 300 to 600 rounds, and with aimed fire that equals a large number of enemies.
  • Perhaps a 7.62mm battle rifle like the FN-FAL, used in single shots, would be superior. A rifleman could carry about 200 rounds. The question would be if the existing human troops are well trained with them.
  • A large percentage of Designated Marksman Rifles.
• It would be an interesting question if they bring GPMGs or SAWs, light mortars, 40mm grenades, and the like. While the ammunition is heavy for dismounted infantry, these weapons are quite effective against a shield wall or cavalry charge.

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Follow-Up: Nice answer by user535733, but if ammo weight matters then aimed semiautomatic fire might be a better idea than automatic fire.

From an armchair warrior:

• 5 kg for a battledress uniform, underwear, boots, spare socks, etc. In very cold climates it could be more.
• 5 kg for an empty backpack, assorted packs and pouches, and load-bearing equipment.
• 5 kg for two full canteens, a supply of water purification tablets, a mess kit, and some emergency rations.
• 5 kg for personal radios and extra batteries, night vision gear and extra batteries, flashlight with extra batteries, first aid kit, emergency survival kit, a supply of chewing gum, a folding knife, toothbrush, soap, and towel, odds and ends.
• 10 kg for either a 5.56mm assault rifle with ten magazines (300 rounds) or a 7.62mm battle rifle with six magazines (120 rounds), plus optics, laser attachment, bayonet, cleaning kit.

That's 30 kg for a soldier to march and fight for a day as an individual. But soldiers seldom operate solo. They often operate in squads of 9-13 soldiers and platoons of 30-60.

Note that there is no helmet or body armor. One might consider a lightweight stab-resistant vest rather than the armor with trauma plates worn today.

• 10 kg for either an underbarrel grenade launcher and a few grenades, or for an anti-tank rocket, or to carry a 5.56mm machine gun (with five 200-round belts) or a 7.62mm machine gun (with one 100-round belt) instead of the rifle, or four 100-round belts for a machine gun carried by someone else in the squad, or a couple of Claymore mines for ambushes, or a bigger radio, or a bigger medical kit.
• 10 kg for half a dozen 60mm mortar rounds for a mortar carried by someone else, or a battery-powered drone, or some repair kit, or whatever. Someone in the platoon might have an axe, several in the squad have entrenching tools, someone in the company has explosives and detonators.
• 10 kg for a lightweight tent, spare clothes, etc. to live in the field.

That's 30 + 30 kg which is heavy but not impossible for trained troops. They would drop one third of that before they come into close combat.

I'm not accounting for any food, except for emergency rations. Get that from the local peasants.

An unarmed native porter could carry 1,600 rounds of 7.62mm or 3,200 rounds of 5.62mm. Get a few for each squad.

Answer 3

Shock and awe.

The idea here would be shock and awe - convince your enemy that they are faced with an incomprehensibly more powerful opponent, so that they surrender and agree to terms. Your enemy is not going to understand what sort of abilities the moderns have. Keep it that way.

Your moderns are not going to be swapping fire with enemies. They are all drone pilots and technicians. I would outfit the moderns with solar powered drones fitted with tactical nuclear weapons. You would leverage this by telling your opponent that you are going to utterly destroy a target, and that they can watch the target be destroyed if they choose because they are powerless to stop it. You are telling them because you are honorable and do not want to waste the lives of their brave soldiers (this is medieval days after all).

Then send a drone up at night and drop a tactical nuclear weapon from 2 miles up.

Then tell them the next target. If they don't capitulate, destroy that one too.

This sort of story might not be as much fun as WW2 era grunts shoulder to shoulder with the medievals. I do like it as a playing field leveler if your opponents have wizards with access to eldritch horrors and the like.

Answer 4

Energy

All conflict boils down to who can concentrate lethal energy onto their enemy the fastest. Modern militaries are powerful mainly due to the amount of energy they can bring to the battlefield. An M1A2 Abrams carries 500 gallons of fuel to push 70 tons of metal around the battlefield over 40 mph. It's turbine engine can generate 1500 HP. So one modern MBT is roughly the muscle power of 1500 horses. And that's not even talking about the main gun. You take away armor, and you take a massive amount of energy and strategic advantage that goes with it off the battlefield.

So now we're left with what infantry soldiers can carry on their backs. If they have enough ammo to put a 3-round burst in every enemy soldier, then lock and load. No special tactics required other than using the primitives to protect your riflemen and shape the battlefield for maximum shooting advantage. But if we assume that the enemy has more troops than you can carry ammo for, or they have other advantages which means you can't simply outgun them, then we need to use other advantages to win.

Information Warfare

Many great battles were lost not due to lack of firepower or manpower, but simply due to lack of knowledge. One side exploited better scouting and the element of surprise to outmatch a stronger opponent. Drones are almost certainly the most cost-effective weapons to bring to the battlefield. A few drones can easily replace a dozen rifles in strategic value. Also, it's better to have fixed-wing than hover drones, because you want to cover distance, not inspect the battlefield. Since you can only afford a few, they need to serve strategic purposes, not tactical.

Another bit of useful tech is the portable weather radar (think: modern fishing boat). Knowing when and where storms are likely to develop helps choose the best times and locations for an engagement. Again, the gear will probably replace several rifles, but just one should be enough to give many miles of weather info. A small radar suitable for boats gives about 50 miles of storm detection, but does require several kW of power. This means you will also want to bring a small generator that can run on, say, paraffin wax or other similar fuels available in that time.

Tactics

Obviously, night-vision gear provides significant leverage for the warfighter, although it really only enables small-group missions. Targeting enemy commanders, supply depots, etc. are just a few ways you can make the most of just a little extra technology. However, one could also use it as a force multiplier by surrounding the enemy camp at night with conventional forces (spotted earlier with drones), using night vision to take out key forces like night patrols, pouring fuel on strategic targets, and then launching a conventional attack with fire arrows, catapults and whatever other siege weapons the locals have available to them.

Finally, the only guns and gunners I would bring are snipers. I'm assuming that the enemy has far more troops than 300 riflemen could defeat on their own. Therefore, the best use of limited guns against a large opposing force is to eliminate the biggest threats with carefully concentrated fire. Snipers with standard .50 cal rifles should be very effective against slow-moving giants and heavily armored humans.

For the fast movers, I suggest some kind of poison-delivery rounds. A slug might not be sufficient to stop a giant rampaging boar, but a sufficient quantity of poison surely would. Cobra venom from a single bite is sufficient to kill an elephant. This is a fairly small small volume which could easily fit inside a hollow point round.

If your allies can prep the battlefield, they can emplace obstacles which slow or delay the fast movers, like trenches, wooden pikes aimed towards the attackers, or even just something as primitive as a field of brambles to run over (think invasive blackberry bushes with their thorns and thick vines spread over a field like concertina wire). This should make it much easier for your snipers to hit them with the poison rounds. Even if the poisons take a while to kill their targets, or even if they don't kill their targets, they should at least slow and weaken them to the point that the fast movers become easy targets for the weaker foot soldiers.

Conclusion

The modern unit should be used entirely for strategic purposes. There is little value using them as conventional forces, assuming large numbers of troops on both sides (which I assume is why you limited their numbers). They should focus on information superiority, cover of darkness, and strategic targets only. Once the enemy loses their highest value assets, their morale will crumble and the conventional forces are likely to rout. It is not necessary for your special forces to defeat the enemy. They just need to upset the balance of power in a decisive way.

Answer 5

Eric Flint has an excellent series called the Ring of Fire, "1632", "1633", "1634"... etc. that you may want to read as a reference to this question. Basically the premise is a giant chunk of WV is swapped with a chunk of 1632 Europe... and what happens after that occurs. It is a good read and some great alternate history bits. You will be interested in Eric's combat sequences with modern firearms, techniques against 1600's style military tactics.

It does present some options that your mercenary force would set as objectives. First, take equipment that would aid in building/restocking/resupplying the force while it waits for regular resupplies. Build and find local sources and alternatives for the main consumables.

You were not specific on how many of the adversaries the force might encounter between resupplies, only there would be several engagements. That detail would create a natural how-much comes in initially so that they don't end up short before the next resupply. Military supply and logistics is very good on this type of planning and unless they are just sending good combat troops to die, they will ensure they have what they need to still be there when the next supply train arrives.

The question of how many hit points are your 9-foot adversaries. If they are like whispy, fragile combatants, rifle fire will do significant damage on them If they are like D&D hill and stone giants, mini-tanks, wide as a barn, bigger firepower will be needed.

Explain what you mean by "...they won't support mechanized armor"? If I have 300 men, on three ships, I would rather replace two of those ships with mechanized armor and only have 100 men and heavier firepower as well as equipment to move it around. 100 fully armored marines represent around 30,000 pounds or 15 tons per ship. Even 200 marines with 15 tons of supplies would be significant.

Answer 6

Have you seen the anime Gate: Thus the JSDF fought? It follows the premise you're suggesting (world rediscovers magical portal, modern military is sent in to deal with the situation), and offers some great thoughts on the viability of certain strategies and weapons. Specifically, the armor imperial soldiers from the magic world have is no match for standard firearms, while cavalry dragons can only be pierced by higher caliper bullets like 50 cal's. The big red fire dragon's scales are even stronger, as strong as tungsten, and can only be pierced by high grade explosives from rocket launchers and the like.

I'd also consider what type of budget your soldiers are on, and what type of compensation they could expect for the job. If the medieval people will pay you in a good sack of gold coins worth several thousand dollars, consider a small squad with moderate gear, and maybe a truck, though since travel is limited then not likely. If it's something even more valuable, like mining rights to rich deposits of rare earth minerals, then expect a platoon or even larger. If they came to your group over a supposed alliance and they are threatening to invade your world as a backup if they lose, then expect a supply response in between the two I gave you. Enough to probably get the job done, but not enough to waste precious resources before everything is known.

Also consider the visibility of the soldiers and their actions. If reporters are kept away and information is suppressed, then that squad could use illegal bullets like hollow points to get the job done easier and quicker, with the public none the wiser. Since the people are so big and the animals are too, this might be more viable if the average giant can tank a few bullets and kill soldiers before succumbing. Or maybe this information is leaked and causes national outcry back home, causing conflict for your squad like delays in resources, or an early recall order. Either way, I'd have men at least carry a rifle and 1-2 backup weapons, with as much ammo that they can walk with. Or, since it will be potentially weeks till resupply comes, bring some horses with a cart or 2 and go old school to carry munitions and ammunition, rather than buy them over there.

Answer 7

The light traveler approach

Some of the other answers here have already explained what you can do with a full range of modern infantry equipment, so I'll take a different approach and explore the most economical route.

Naturally, the most efficient method is to use your allies effectively. You want to link up with them as soon as possible. This way, they can handle more mundane parts of warfare while your specialized killing machines can be inserted at key points to dominate the field as necessary.

You don't need much to work with: just give your soldiers standard assault rifles, plenty of ammunition, plastic explosives, and night vision goggles (with lots of extra batteries). And some horses.

First, to get to your allies. A band of modern soldiers should have no difficulty venturing across even hostile territory without too much trouble. You're not looking for a fight. So just avoid terrain that looks entrapping or difficult to defend. The mobility of being a small mounted group should let you easily outmaneuver and avoid any opposing forces. The night vision goggles are an extra precaution against nighttime surprises and ambush attempts.

Once you've joined up, you can just march alongside the allied army and provide (devastating) support. Your allies can set up defensive barriers (wood is good enough). Soldiers operating against 12th century opponents with no need to worry about return fire or giving cover fire can make 600 rounds go a long, long way (I would bring more anyway, maybe thousands per soldier). If you add in the extra advantage of trenches and other defensive emplacements, giving you plenty of time and cover to aim against an enemy with no guns or armor capable of stopping bullets, then you can basically hold out a position indefinitely until you run out of food. And the bullet:kill ratio will be close to 1:1. If you wound someone, you can leave them for your allies to pick off later.

In a pitched battle, your allies can line up in traditional formations, which are extremely effective against a disorganized enemy force. If the enemy decides to line up as well, then you send your soldiers out in front and open up on them with (carefully aimed precision) rifle fire until they become disorganized again. Then you can pull back and let your allies mop up. Repeat as necessary. Your side will be essentially invincible in the field.

But the open field isn't everything. Medieval warfare is mostly about the unpleasant business of sieges. I've already explained how you can easily defend against a siege, so the only thing left is sieging the enemy. That's what the plastic explosives is for. So there are no sieges. If you want to go with heavier equipment, you can do mortars. But plastics is the lightest approach.

Answer 8

Giant domesticated boars, as big as a wisent.
Giants of 9 feet tall armed with 12th century gear like spears and maille armor.
Giant cavalry similar to a norman knight on equally large horses.
Humans with crossbows as well as shield walls with spears and axes.
Wolves large enough to hunt the above boars

You'd probably want somewhat larger rounds than 5.56 or 7.62. The Gerpard Lynx might be perfect for this (and looks cool). I'd also go with recoiless rifles - the Carl Gustav is a modern option, and you have a range of useful rounds for it.

You might also want to go with landmines (and given time, set them for sensitivity for larger targets, so your own troops can cross over and pull the enemy into a trap). Considering sheer size and the fact that they're in armour, I wonder if anti tank mines would work.

Assuming the rules of civilised modern warfare dosen't count... White Phorphorous would do quite a number on an enemy, or even a flame thrower.

Modern militaries are also likely to have better night vision, and considering these are pretty large targets harassing attacks in the middle of the night might prove effective. Setting barns and food supplies, or even military and civilian housing on fire, painting rude graffiti on walls, that kind of thing.

More than armour I'd love some heavy machinery - trenches, and punji pits might be effective, though even a 9 foot tall giant would not have a good day stuck in concertina wire. An electric fence or three would be.. amusing as would cattleprods as meelee weapons. You're going to need power, but that's a renewable (as you'll see).

While I'd love heavy construction equipment, considering you have giants too, vietnam war style pit traps (with really large sharpened spikes covered in sewage...) large wire snares, and even concertina wire would work.

Probably worth considering mixing a roman style palisade base (with towers!) with hit and run tactics (you're smaller and pack a bigger punch).

Its also worth equipping your local ancillaries with more modern versions of weapons they're familiar with, and upgrading their gear. Imagine catapults with modern bungee cords for tortion, and ballista firing sharpened rebar. They will also be able to process materials faster, say with chainsaws, and tools made of 'modern' steels.

I'd suggest building a wood gasifier or steam engine/stirling engine, and using that to power a generator (so you can charge your modern gear). Solar panels would be 'nice' but a steam engine is going to be technology you can use to bootstrap other tech.

Radios would give you a massive advantage as well, though I suspect many modern troops would give their right arm for GPS and a cellphone. The ability to know where your own troops are, and the enemy is means you have a much better ability to dictate the battlefield.

Also, folding or electric bicycles with carts would massively improve your ability to move troops between areas, though an updated, electric version of Vespa 150 TAP would be amusing

While in theory, you could take out a drone with a spear or crossbow bolt, they would be a useful force multiplier, being able to see over the horizon, walk in fire and possibly even dropping small explosive or incidiary devices in the midst of the enemy. A particularly vicious way to use one would be to use them to sneak in and poison wells inside beseiged cities or enemy encampments. Bio/chemical warfare is frowned upon, but the effect of a teargas canister or worse in the middle of an enemy formation would be... catastrophic, especially with mounted troops. They're a reasonable, lightweight way to get air power, and you're probably going to use them as a harassment/recce tool. Consider both machines like the Aeroventure Raven for recon and target painting and drones with a little more payload as very light bombers.

Answer 9

We accept their request for help, but we don't go and help by marching armies around having pitched battles, because that's silly.

Instead, we send through the parts to build a zeppelin, and a bunch of bombs (plus some engineers to build a base for said zepellin, a whole lot of fuel, and a regiment of infantry to defend said base). We then fly said zeppelin over the enemy capital and drop a note saying "surrender or die". When they don't surrender, annihilate said capital and move on to the next largest city. Repeat until the enemy ceases to be a problem.

While we're doing that, keep on shipping through more industry - get oil drilling going for a starter, and industrial farming, and all of the various industries needed to produce a strategic bomber and/or a cruise missile. If there's still an enemy left by that point, start using those as well to speed things up. Once the war is over, do some "negotiating" with our allies about who exactly is getting all of the land that used to be enemy territory.

Answer 10

The enemy will not cooperate (and that doesn't make a good story anyway). How will a smart opponent react?

Opposition:

Once you know how to do it, ramping from 1100's tech to 1800's tech is a matter of many months or very few years. (See Flint's Ring Of Fire books.) And 1800's tech in large masses will give even 2000's tech a hard time. Controlling the supply of iron ore, carbon fuel and nitrates will become a major point after that knowledge gets out.

The local opponent is going to sooner or latter figure out that the modern weapons are dependent on consumables that are not available locally (much of what a 1100's army depended on came from "scavenging" or could be to some extend replaced on the move), the supply lines, not the front line then become the locals target.

Both sides will be maneuvering to try and force an engagement on their terms, the locals when they can stretch the modern supply lines as long and as fast as they can and with as many successive waves of cannon fodder as they can manage, each emerging from good cover to force them to be killed retail rather than wholesale. The moderns will seek battle when they can amass the most logistical support and force an engagement with a unit of chosen size and in a large open kill zone.

One other tactic for the moderns; recruit the enemy. Make being captured in battle preferable even to avoiding it all together. Works even better once they know they are being sent out as bullet sponges.

Answer 11

Support Units

Since you said the resupply intervals are relatively large, my suggestion would be:

• ditch 200 of your troops
• acquire 4 - 6 artillery pieces (e.g. M777 155mm howitzer)
• fill the freed up loading space with ammunition

Tactics

The safest way to take out an enemy is when he can't hurt you back. In order to do this, maximise your effective range (nothing says 'Good morning' to your enemy like a good few HE fragmentation shells). You wont need to make your reconnaissance force to be front line fighters, thats what your allies are for. Just let some of your men scout out the enemy encampment before an engagement and then rain down fire and brimstone at the break of dawn from a comfortable 24 km away. The remaining foes can then be cleared up by the knights and peasants.

As for logistics, just hook horses or mules to your artillery and *boom*, you've got towed arty, which can set up, engage an enemy force, and retreat unseen.

For extra effect, bring out the chemical weapons. From phosgene and mustard gas up to sarin and the like you have a wide range of agents that could wipe an entire army within a few barrages.

Answer 12

To me, those expected enemies look to be less tough as African big game, with only the boar being really hard to kill.

Thus, since 7.62 NATO is almost as good as .30-06, which is a good general purpose round for African big game, I'd send the soldiers in with a modern variant of the AR-10 rifle with bayonets, and lots of ammunition.

In addition to that:

• first aid kits (band aids, tourniquets, tape, gauze, sulfa powder -- antibiotics need to be refrigerated or injected, and that's suboptimal -- and good old aspirin.
• MREs, because the fantasy food won't be digestible at first
• Water purification tablets.
• 80mm mortars plus ammo, including WP
• entrenching tools
• toilet paper!!!
• Claymore mines
• Normal marching gear like ponchos and socks, socks, socks and even more socks.
• Radios
• Batteries
• Solar battery chargers

If there's any room left, send in some FN MAG (since they also use 7.62 NATO) light machine guns.

Bottom line: keep it simple, and think Light Infantry.

Answer 13

This is the combinaiton i would see:

• Communication (radio, tactical com)
• Reconnaissance Drones with IR cameras
• Portable Radars
• IR Cameras/detectors
• Night vision goggles
• Navigation (a little tricky but obviously not standard GPS but some kind of VOR)
• Light machine pistols for near range defense
• Designated marksmen rifles for distant killing without carrying a big amount of ammunition
• landmines to lock the enemy in forest areas
• Also tools (Chainsaws for wood processing)
• Electric lights, high voltage fence, portable generators to set up base defenses
• Mini guns for the base defense
• Bicycles/Mountain bikes
• Potentially light motor bikes
• Poison/germs for the water supply of the enemy
• Phosphor grenades for burning their supplies
• Water filtration units
• Modern Nails, Screws, wires
• Explosives for forming artificial caves for bases
• Concrete+steel doors for securing these bases
• A loot of dry, concentrated food
• Experts in communication in order to subvert the enemies morale

Strategy: Take it slowly. Set up base by base, install a defense network between the bases. Focus on locating and the starving/poisoning the enemy. Put bases to clean water supplies. Set up Dams using the tools to flood areas where the enemy might still live and take water from their villages. Focus on continually weakening the enemy. Dont try to conquer, but make sure that the cost in life of the enemy is much higher than yours

Answer 14

your question is tricky because of the requirement in term of resupply, weight capacity and manpower limitations.

Logistics limitation will have a dire impact on modern way of warfare, days of resupply is "ok" but week aways is a really hard requirement. Today military is heavily depended on daily logistics, unit is by default equip for a day or two of heavy fighting (accounting for soldiers and unit supply). a soldier carries roughly 200-300 ammunition, a mortar team 10-20 obus often every man on a unit take one or two mortars obus for the mortar team.

you could inspire your troops from paratroopers because they are designed to operate behind enemy line with limited supply.

The excellent answer of user535733 will be fully effective in a situation where supply is not a limiting factor.

I don't know the size of the enemy troops but there will be a point where there is no ammunition left.

Your tasks force must use their stocks very efficiently.

Go for either shock approach were you panic your opponent with overwhelming firepower.

Go for long and prolonged warfare were they use they superiority in firepower to support their ally only when required in order to gain time for more troops supply to come. also using drones and special forces to destroy strategic asset could help.

Another idea is instead of focusing on defence earth troops could assemble as a striking force:

• for a counter-attack at the right timing

• For a raid in enemy capital or other highly valuable assets.

• Or try to disorganize enemy force hitting behind the front line in a guerrilla warfare style: communication lines, political, religious, storage etc... forcing the enemy to divert forces and/or causing political troubles..

With modern technology such behind the line approach is easier reconnaissance is easier (modern optic can see up to several km), a flying drone can also provide accurate Intel km away. and so target identification and enemy force evasion is far easier.

I am not sure you can win with equipment alone, you have to adapt to the logistic constraint and pick the right tactical approach to accomplish your strategic goals. The material you are taking will depends on the tactical approach you choose.

I really enjoyed your question so I ended up putting an exemple. In this scenarii mission would be considered successful if it manages to gain several months of time by rooting the main enemy army and weakening his political power. Critical success will be that your victory leads to civil strife in your enemy territory or isolating in the international scene.

Example:

starting point:

• Communication to earth is rare up to several weeks.
• Our ally is waging war against foes greatly superior in number.
• To earth understanding, our ally is about to be overwhelmed.
• We accept to send in urgency a task force of 300 men to help our ally.

Strategic goals:

• Allowing the survival of our ally.
• Protecting much as possible ally valuable assets and population.
• destroy the will to fight of the enemy.
• Prepare an operational camp for the additional force earth may send (maybe our ally will be our next conquest, I heard this planet is rich on oil and gold...)

due to the limited amount of time, no specific material can be made, furthermore, because people there are far stronger than us no close combat is suitable. Earth strategic command then decides to send a tasks force (Alpha) able to adapt and implement the required tactics depending on the situations. Operation code Name Jeanne.

tactical axes:

• Establish an earth commandment on the ground.:
  • Organize and coordinate earth force
  • Centralize Intelligence
  • share and planning with our ally
• Intelligence and communication
• transfers low-level technology to our ally:
  • greek fire
  • early black powder
  • Hwacha
• defence of our ally:
  • counter enemy incursion
  • protect valuable city
  • support of our ally in battle.
• breaking enemy will:
  • use of guerilla warfare
  • killing of commander
  • the killing of the political decider
  • sabotage of communication line
  • destruction of food and water contamination.
  • biological warfare?

Men, organisation and material:

HQ (~30 men)

• The commanding officer (M.strogoff) and an officer in second.
• 5 staff officer
• a radio unit (several radios, and a large radio antenna)

• specialists

  Directly attach to HQ (30 men)

• Light drone intelligence.

• diplomatic mission.
• scientific misison.

An Elite infantry force (160 men):

• 2 company of elite infantery (example (2éme Regiment Etranger de Parachutiste, 101 aéroporté, 1er RPIMA)) with standard equipment.

Commandos strike force (40 men):

• Elite infantry unit able to operate well behind the enemy line for a prolonged period of time. (Navy seals, Commandos Marine, Groupement Commandos Parachustiste)

Elite reconnaissance unit (20 men):

• Reconnaissance specialist operating in small teams able to operate far behind the enemy line. (Nageur de combat, 13th Parachute Dragoon Regiment)

Equipment:

• Due to the lack of oil and motorisation, no heavy material can be used.
• Add additional support in explosives (c4).
• If enough places replace machine gun of the elite infantry force by heavy 50. machine guns and ammunition. (everything that dares approach in close order even giant would be cut in half literally)

• If enough place can be made use of (1-2) artillery piece design for mountains warfare (they are 'light' and can be taken to pieces to be moved by hand) (Combining the long-range of modern artillery and the intelligence gathered could allow cherry-picking of important and opportunity target)

• A light Radio tower. (I am not a radio expert but you may need hardware to broadcast and receive far away?)

• light flying drone.
• Diesel Electricity generator (if they're old enough you can use vegetal oil instead of diesel, for radio and drone)
• as much as you can of additional supply.
• Minimum food (we relly on our ally for that)

Once linking up with our ally tasks force Alpha will Establish a command post which (which may be moved if needed).

In order to assess the situation, the diplomatic mission will try to gather as much intel they can whereas drone start to fly and specialist draw a situation map from those data. There is no highly precise definition map neither GPS so they have a lot of works.

The scientific mission collects data but also transfer technology so our ally can at short terms have some early black powder and greek fire. In at least his major city. At long term, we want to give them modern metallurgy (and firearms?) which will give them a very valuable advantages in battle.

The Elite infantry stays near the command post. It is employed in a reserve/support fashion to avoid our ally army to be decimated. (Due to limitation they won't be able to fight more than a couple of days so each of their intervention must be needed to accomplish strategic goals).

Light artillery only opens fire to an identified target and only on HQ green light. They do not want to waste ammo to kill enemy forces they want to pick the nice tent with gold in the enemy camp. Or the mountains near the enemy columns to start an avalanche. Or the bridge the enemy is crossing. They only engage enemy force if Earth troops need fire support to escape encirclement.

After some days situation may become clearer, then Elite reconnaissance could be dispatch to gather intel and sabotage enemy communication line (bridge again), a mine that stops a convoy from a time (people then do not know explosive so seeing a man exploding out of nowhere may stock a columns for a time or even forcing them back). If you don't want to respect convention (they do not have sign any ?) contaminate water well and river with poison. But also dedicate a couple of men to try to identify and to kill (sniper artillery) the local political leader (or all if they are several).

The Elite Commandos are used for daring raids beyond the enemy line on depots or logistics column or lightly guard camps. Because of the strength difference, this unit is likely to suffer heavy causality. But it is important the enemy never rest and that his food depot burns.

Avoid losses at all costs, use your superior Intell and technology to avoid to fight and deprive the enemy of his own logistics, force him to have much of his force protecting his logistics, destroy his will by killing the leader and the use of modern explosive. be reckless and pitiless as humans are. A large army without food or water is a grave in becoming.

And pray that the Wizzard our heard about is just a chimaera. and that earth doesn't forget you.

Answer 15

Warfare is hell.

Modern Engineering

The first step would be to set up a defensive perimeter. It would take an engineer company (for example the 397th Engineer Battalion) with some horse-drawn carts for daily supplies (we requisition that from the ally) and tools (shovels, axes, chainsaws, fuel), several carts for gravel (requisitioned locally), steel rebar (import, takes some of our space), wood planks (requisitioned locally), rocks (requisitioned locally) and hard work as fuel supply and weight limits in the supply route are low. But it will work.

The Engineering company of 50 is grouped in 5 groups. Everybody is armed with automatic rifles (M16, AR18, G36) and has about 2 boxes of ammo (typical packing: 800-1000 per can) in their deployment kit. One in 10 has an 40mm grenade launcher like the M203, one gets a DMR. Everybody gets a combat knife. Spade, pickaxe, cutters and machete complete the armory.

Tasks

Within just some week or two they will errect a modern version of the Maginot line over a sizeable stretch. To this, they also build gravel access roads.

The Engineer company subsequently moves on to extend the line to defend the docking/landing area stockpiles supplies. Each trip a ship comes in, it also should drop of parts for construction as well as fuel barrels. Diesel for construction equipment, gas for the chainsaws and Kerosene for later use. It doesn't even have to be much: each shipment just brings in a pair of barrels instead of 2 men, so it will stockpile over time.

2nd Wave: Mountaineers

Meanwhile an infantry batallion or two (ca 50-100 men) move into the fortified positions and mans the fortifications. It might be better to send units like Mountaineers, that are better trained and have heavier equipment. I think the Bataillon médian de chasseurs ardennais might be an excellent choice to use a template for such a unit, but that's just because I love the fact 40 of them held up Rommel and his 7th Panzer Division for 18 days until they ran out of ammunition.

Armed with "light" 60 mm mortars, squad machine guns, possibly a heavy machine gun, some DMRs and everyone else with automatic rifles, they can hold this position as long as ammunition is there, which could be pretty much indefinitly (as elaborated here) as supply caravans roll in and increase the stockpile over time. No sane military would send a crew of soldiers into an area where they can't supply them. Or at least none that learned from WW2. Since roman times, human warfare always was around logistics constraints and WW1 and WW2 did teach a lot about how to keep logistics flowing in the worst situations.

Besides the 60 mm mortars, they also might bring light field artillery, which can be drawn by horses. 7.5 cm Pak 40 fits this bill and weight about a ton and a half. If 60 mm artillery isn't enough, one might go for 100 or 120 mm mortars, on the cost of ammunition capacity, but it would turn any 12th century fortification into a shattered field. If the PAK 40 is too heavy, short-barrel variants might be a better fit - and some of these might even be disassembled for transport. For example the 75 mm light infantry gun the germans used in WW2 had variants that could be turned into packages and weighed only about 375-400 kg for 3500-5100 meters range.

For mowing down infantry, quad-mounted machineguns like the M45 Quadmount or the infamous Flakvierling could be drawn by horse and haul their complement of ammo - and only weigh 1 or 1.5 tons each, making them equivalent in deck space to a 75 mm field artillery.

Guerillios

As an alternate to regulars, sending in irregular troups might be an option. Irregular units means troops that are not national military. Guerillia Warfare is the modus operandi of such irregulars - and La Resistance was a particular large and well organized group of Guerillia during some parts of WW2 (mainly during the German occupation and before D-Day).

Think Ernesto Che Guevarra. In 1956 he had ca. 20 men left of the original 82 after the landing in Cuba from the Yacht Granma. They connected with local guerillia networks to arm up, resupply and reinforce. Their most vital supply item was ammunition - food they sourced from the locals for help. They turned locals into Guerillios (which loosely traslates into 'fighter' or 'warrior'). At the time of the Battle of Yaguajay two years aftet the Granma landing, Che and Castro had more than 450-500 men and a tank.

Armed with every gun they can get their fingers on, there is no standard equipment in the Guerillia troops. They fight with what they can get their hands on, but they strive to standardize on one type of ammunition if possible. In the case of the IRA it was during the riots a mix of AR-16, M16 and AR-18s, relatively standarized. They also pack lightly: drawn out fights are a bane. Instead Ambush, Assasination and blowing up supply convoys are often preferable to 'honorable' battlefield fighting. They blend in with the surroundings, try to wear the clothes of the people that live there and work with the sympathies. Mao Zedong did summarize Guerillia Warfare like this:

The enemy advances, we retreat; the enemy camps, we harass; the enemy tires, we attack; the enemy retreats, we pursue.

Logistics warfare

To accomodate our need for logistic backup, Fantasy-World will have to run a massive expansion on shipbuilding, aided by modern engineers from our side that helps in streamlining the making of the hulls as quickly as possible. Gone is the wooden keel and replaced with a steel frame, to which the planks are riveted. Silicone for sealing instead of horse-hair and tar. Each ship that returns could bring another frame that was preconstructed without taking deck space from on our side (put it over the ship like a tent) so the longships could multiply like flies.

Engineering crews could probably easily refit the longships with small fuel driven motors and reinforce the hulls to allow heavier transport to get them to an average speed of 6 knots and independance of wind and thus massively streamlining the delivery times, though not necessarily cut them down.

Reinforced hulls would also allow the transportation of Jeeps and light trucks and larger field artillery in addition to motorcycles and light infantry guns, which were possible before. No tanks, but still, Motorisation makes the warfare much more mobile!

Our modern logistics meanwhile would work as much as they can on speeding up the loading of the longships on our side. For example we could skip the trip from wherever the portal is to our shores. No matter where the portal is, tender vessels can wait in the area and stock the longboatd out there on the open sea.

Our reinforced boats also are probably might be just big enough to transport heavier engineering equipment - even if it has to be taken apart. Think Jeeps with a plow or an excavator on the back. Once the first excavator is on the other side, we can extend the trenches much faster. The bulldozer and gets assigned to building supply roads and clearing an airstrip together with the engineers. Note that we might want to shift to shipping more fuel and ammo at that point, entire shiploads of these supplies in addition to reinforcements.

Once we established our frontline - which pretty much can be held forever, time is no longer of an essence. Supplies will accumulate in the landing zone as transport volume (hopefully) increases. It doesn't matter that ships take weeks, if you just have enough ships.

Taken to the Air.

The Kerosene is for simple biplanes, which are light and easy to be taken apart for transport, or even better, folding-wing planes. Most don't actually need a landing strip, they could land on any field that is flat and large enough, though an airstrip is clearly preferable. For a squad of 3 planes, we'd need 6 pilots, about 4 ground crew and an engineering crew of about 5. Their tools and equipment including the planes (with detatched wings) can be transported via carts, and most turboprop planes are extremely reliable, making the need for replacement parts somewhat small.

They serve as spotting and CAS planes. They push the perimeter from about 3 kilometers to a couple hundred kilometers kilometers, which in combination with radio technology, would allow much more targeted defense or offense along the perimeter as well as stratetgically destroying supply trains. They might need to be used sparingly due to fuel constraints, but their intimidation factor and attack tange could turn the tide in some battles.

Onto the attack

While our troops don't get to become mechanized troops in APCs, the increase of transport volume for fuel and the presence of light trucks - think Opel Blitz - and towed light artillery and light anti tank guns has turned our battalions into motorized troops, which are much faster in deployment. Once enough fuel has accumulated, the battalions roll out in a Blitz with CAS-support, then the gained lands are fortified. This is repeated till the evil army surrenders or is turned into a stinking pile.

If the Blitz isn't showing enough results, our military also might ship over some light missile artillery to aid in the attack. Katyusha for example would stretch the attack range of our assault force to 5500 meters, devastating an army that can't even see our advancing troops and turning a medieval city of the opposing forces into a field of rubble.

Total Annihilation

The City-Killer Batallion

Or, we could just send a single shipment. A single shipment of 10 M29 recoilless rifles, 30 men with Armalites, a box of ammo per man. And 10 Mk-54 Davy Crockets. Once in Fantasy world they requisition some horsecarts, stuff them with materials and food and embark into the enemy lands. It's a small caravan, they will use side roads if possible and try to evade any enemy contact, killing whatever they encounter. Tehy march until they get close enough to the first enemy administration center or military gatehring zone. There 3 disembark with one recoilless rifle, a Davy Crocket and the rest circumnavigates the place, marching on to the next target, possibly leaving the carts behind as they distribute and go into their respective positions. Then... A single Radio call and....

BOOM. The first target is turned into nuclear wasteland. Only then we send our demand: Total surrender within 24 hours, or the next place will be annihilated - we don't tell them which. No answer? Laughing? BOOM! Still no surrender? BOOM! We can go on... they don't know how many we sent. They only see that not surrendering immediately results in cities turning blazing ashes.

Total Infiltration

We can take this even to the next level: Not 3 men per nuclear explosion, 1. We modify Davy Crockets to detonate on a trigger signal instead of on impact. Then, we gold-plate and decorate the housings and send them as Tribute to the enemy administraors we can reach with one of our own spies to 'gift' it to the governers in exchange for a ceasefire or release of captured troops. Once they reach the target, we simply state the conditions for their surrender, and if they decline, we blow up the whole town.

Then we send a new ultimatum to the next we can reach, together with another agent armed with a bomb. But our terms are different now: Total, unconditional surrender or total annihilation.

Answer 16

Mostly assault rifles.

Might want to skip the carbine versions but otherwise I see nothing there that requires anything more. An assault rifle should have enough penetration to penetrate natural or pseudo-medieval armor.

As for doing enough damage, you just keep shooting until it drops. Assault rifles have good sustained rates of accurate fire compared to previous infantry weapons so you can just keep pulling the trigger. They even come with helpful burst mode that is still decently accurate at close range.

Main benefit here (and in general) is that you only need to carry one kind of ammunition and can easily get more damage output just by shooting more. You are in control and can always get the damage you need as long as you retain some control of the situation. No other weapon can match this flexibility and economy of force.

Sure an AMR can stop the big guy in one shot but for anything else there is overkill. A grenade kills more people with one shot but is overkill if there is only one enemy. With bunch of soldiers with assault rifles, they just shoot until the enemy stops. There is no overkill. No waste of resources. No unnecessary collateral damage.

Assault rifles are also relatively cheap since both the weapon and the ammunition are mass produced in large quantities. They are also easy to use apart from very close range where length might be an issue and soldiers are already trained to use them. The relatively low recoil even makes them convenient to use.

Other weapons

A light machine gun uses same ammunition but can sustain higher rate of fire and has better accuracy from range. Since it is more or less standard equipment and does not require another ammunition type you might want to carry one for shooting bigger enemies from range for extra safety.

A designated marksman with his rifle is also pretty standard. They generally have fairly good ammunition economy so should be fine. Marksmen and snipers are also extremely efficient against enemies unfamiliar with the concept or simply untrained in proper tactics to use. So in your scenario one or two would literally make a killing.

It requires another ammunition type but an automatic pistol or compact SMG for close range combat might be worth the weight. You usually would not need them but on the occasions you do, you'd be happy for carrying the useless weapon and the useless ammunition for it. Since you'd use them rarely, they should not end up using much of ammunition.

The reason for rarely using them is that with firearms being your primary edge you'd do absolutely everything you can to avoid close range combat. Swords and axes are scary up close and personal. Which is why you'd be happy to carry a pistol or SMG if you mess up.

Considering tough enemies with armor, I'd suggest FN 5.7×28mm based weapons. It is a newer cartridge designed to address issues with penetrating body armor so it should do. Weapons using it are also fairly compact and modern. (Less extra weight.)

Many armies routinely carry recoilless rifles (or missiles) in case they run into vehicles. They do not really make sense for your criteria due to limited ammunition but armies that carry such would probably still do so. It is a new world, who knows what you run into. Anyone complains about the weight just say something vague about rumours of a dragon. And they are light weight to carry anyway.

In short, pretty much the same as infantry usually carries. The sad reality is that modern infantry weapons evolved in battlefields that make any fantasy world not derived from the work of H. P. Lovecraft look like a vacation resort. There is lots of thought behind those weapon choices. And as far as military is concerned the weapon soldiers know how to use and are already carrying is the best weapon anyway.

Other stuff

Tactical radios for communication. Cameras and recording devices. Binoculars and maybe night vision gear. Portable computer for reference. A smart phone can do many of these at some level and you might want to let soldiers carry some. A solar panel for energy and other survival equipment. Bicycles should work and some armies have used them for tactical movement. This is all still the category of normal stuff. Armies are designed to survive environment that tries to kill them. That the enemy uses swords and spears instead of artillery and wyverns instead of helicopters doesn't really make anything they do invalid.