So, I had an idea for a fantasy world that summoned a 'giant' (actually a regular human) to aid them in their battle against a rival nation, and I was wondering about tactics and uses in war. Magic is pretty low-level, and is mostly based on communication and warding fortresses/cities. There's some combat uses, but not much. There's plenty of food, so no need to worry about that, and the tech level is quasi-medieval. There's catapults and scorpions, and gunpowder is in development. The 'giant' is big enough to carry their elephant analog in the palm of his hand, and retains his strength and agility from Earth. What would be some good uses of his abilities?
Considering the prospective size difference and the simplicity of the weapons, the only possible harm would be a lot of gunpowder, making the giant practically undefeatable even without protection. What use in combat would an undefeatable monster be?
He would need good infantry support to keep away the guys with ropes and harpoons... Apart from that, a smart enemy would avoid pitched battles and just operate where the giant isn’t. US military was the proverbial giant in Afghanistan in 2001 but 19 years later the Taliban basically are the victors. Also, I know you said plenty of food, but in a war food is always an issue and tiny people feeding a giant who can hold elephants in one hand would be a massive issue. Medieval and early modern armies typically supplied themselves by “living off the land”, eg pillaging every village and farm they came across, even if the village was inhabited by “their” people. Civilians who managed to survive the wave of rape and murder that typically accompanied that might well die of famine and disease afterward.
With the Fantasy physics breaking equivalent of FTL in Sci-fi.... I think Shad, covers how effective a smaller 2-3 times taller than a human sized giant, but still applies for the most part. (first part of the video explains this, that can be extrapolated as needed) A giant of such scale as yours, would still need some kind of defensive armor. The enemy could use poison tipped ballista bolts on exposed areas, that could hinder/kill them with enough hits delivering a potential lethal dose. At least you don't have to worry about them being killed by massive physical damage from catapults or through mass cuts from melee bladed weapons. Fire could be employed as a deterrent, so long as the giant is biologic and not a walking mountain of rock. Employing Chevaux de Frise ( https://military.wikia.org/wiki/Cheval_de_frise ) are another handy countermeasure to something that size, since if the feet are unprotected, then the injuries would have potential to get infected over time, or kill if the points are coated with poison. Good luck.
What you need is a trained group of anti-giant operatives, with equipment that allows them to move in 3D and with carrying disposable blades (so that don't go blunt in combat). They'd be, I dunno, picking a random name out of thin air, a kind of corps that does surveys.
If he’s that big it would probably just be more efficient to give him a sledgehammer and steel toe boots. If I were his enemy I would vacate fixed positions and hide out until he eats everyone’s food and becomes a liability for his own army.
Here's the thing. At a rough calculation, your giants stand about the equivalent of 60m tall. That's 50% taller than an Ultraman. There aren't a lot of elephant sized boulders lying around. The average boulder used in catapults and stone throwers would be a pebble held between the giant's finders. Castle walls are usually about 10-12 metres high. The giant stands 6 times higher than a castle wall. It'd be easier for the giant to just kick over the wall.
Better use would probably be just loading siege engines. Granted, most stones would not be that large, but some could be.
There's a romanticist fairy-tale written by one of the most renowned Hungarian poets. In it, the main hero passes through an "un-crossable sea" by calling upon his giant ally who carries him on the shoulder while walking through the ocean. A giant of the size you described can have a multitude of "uses" for transportation. He could lift people over a castle wall, aid armies across ravines or transport a handful of people across sea channels. I estimate your giant to be between 60m and 80m, which means he could easily pass from Dover to Calais waist-deep in the water. Could even shift through the water from Denmark to Sweden, then from Sweden to Finland. Now imagine you have a naval battle ... ... yes. The giant would have only been knee-deep in the 20m to 40m-ish waters of Trafalgar.
Ballista's and projectile weapons wouldn't have the velocity when scaled up. Skin is pretty thick and tough. We need explosives or compressed air powered harpoons to get through the blubber to kill whales, and they're not that much bigger compared to this scale jump. Nor would they have enough poison to scale up to giant that big if they were fortunate enough to have a weapon with the velocity needed to pierce the armour and skin. I know this isn't meant to be scientifically realistic, but it needs to make sense or the fantasy element falls apart. There would be defensive countermeasures but I see them all being defeated rather easily by either armour for direct fire attack, or simply stepping over any defensive emplacements that would hinder a ground attack. The giant can get hurt, sure, but defeated, I doubt it. As mentioned, at that size with that scaled up power he could just kick over castle walls. But the question was, what military role could it play. Well, it would both terrify the enemy to routing, or simply wipe them out by bulldozing forward with squish 'em tactics. Basically, send him in first. Personally, I think the giant is too big or the little uns need better tech / magic.
Even with firearms, they'd have difficulty. Consider this - a hippo has 6cm thick skin and is almost bulletproof. A human's skin is 2mm thick, scaled up to your giant's size, that's 6cm. Add to that normal clothing, and you then also need to penetrate 3-6cm of fabric, essentially rendering your giant bulletproof. Cannon would do some damage, but it would be less effective than shooting someone with a BB gun considering the miniscule size of a cannonball. It would be more like a pinprick. And your giant would be on top of them before they had a chance to reload, given that the giant would cover the equivalent of 50m in a normal walking stride, or perhaps 1km in 6 seconds, nowhere near enough time to reload. You need to make your giant smaller.
Exactly this. Cannonballs would be like slow bb gun pellets. Make him smaller OR I like the tactic of the enemy hiding until the human consumes too many resources and becomes a drain on his own army. It's the tactic used by the Russians to defeat Napoleon. They couldn't win on the battlefield outright, so kept retreating to draw him deeper into the Russian winter and stretch out his supplies, and most of his army died from the cold or hunger or disease until it was weak enough to fight. Also, they only have 1, so a scattered army that goes all over the place or uses guerilla tactics could not be fought by a single giant, rendering him less useful. Like the Tirpitz German battleship was in WW2 which pretty much sat out the whole thing. So maybe change the nature of the enemy.
So your giant would weigh 1,953,125 times as much as a 170 pound 6 foot human: 332,031,250 lb. ≈ 166,000 tons. Someone who's good at math tell me if that looks right. Whereas a twelve pound ball would have weighed only 168 times as much as a minie ball. So bullets for this giant would probably be smaller proportionally than a grain of sand would be for us. For perspective, here is a really big hill, standing about 1000 feet in prominence above the surrounding countryside. The road that the photo was taken from was well over a mile away. People like to hike up there and take photos because they can see for several dozen miles. That is a big giant. A 90 foot giant sounds about right to me; that's about the size of a tallish tree.
I make him to be about 2,200 tons, based on a height of aproximately 30 times that of an average human being (weight is proportionate to volume, which is the cube of the height). He stands roughly 180 feet, or nearly 60m. I base that on the description that he can hold an elephant in his hand (making his hand about 5m long, or about 30 times the length of a human hand). If he can hold an elephant just in the palm of his hand, he'd be twice that size and weigh over 17,000 tons.
Yes, but everything is relative to the natives, i.e. to them, he's the equivalent of a 60m tall giant.
Just imagine if ants had human intelligence and were at war with you. They’re not going to bother building or defending structures you could stomp. They’re not going to come charging at you in stompable columns. They’re not going to line up in rows trying to bring you down with tiny cannon. They’re going to hang around in crevices or tunnels or between walls where you can’t reach. They’re going to attack your food supply and poison your water if they can get to it, or maybe set little fires in highly inconvenient places. If you have ant-sized allies they’ll attack them when you’re not around. Overall they’ll let you exhaust yourself tearing up the terrain looking for them, and making new enemies along the way, until you give up.