3
$\begingroup$

Say there was a war, taking place on the top of a large mountain (not very tall, say 3000 feet, but the base is double the area of a normal mountain). Would it be possible for an two armies constantly battling each other on the top of a mountain, with near-impervious axes as weapons to flatten the mountain by 1000 feet or so?

If not, how much power would that take, and would it at all be possible, stretching the realm of plausibility for the sake of a good story?

Edit: To answer some comments

The technology level is comparable to medieval weaponry, but with stronger materials (for sake of not explaining every little detail about why, assume jackhammer power instead of pickaxe type thing)

$\endgroup$
7
  • $\begingroup$ Are they fighting the mountain, or someone who is living within it? $\endgroup$
    – notovny
    Sep 13, 2022 at 20:55
  • 2
    $\begingroup$ Axes are very extremely inefficient tools when used to move dirt. They would work faster if they ditched the axes and used their bare hands. (And I have no idea what you mean when you say that "the base is double the area of a normal mountain". Do you mean to say that this is some sort of large inselberg? How lartge is the base of the mountain, really?) $\endgroup$
    – AlexP
    Sep 13, 2022 at 20:55
  • 1
    $\begingroup$ With hoses powered exclusively by the gravity of the water involved, miners in the 19th century literally washed away several mountains. These were quite substantial flows with significant range. What tech level are we at? en.wikipedia.org/wiki/Hydraulic_mining This is very similar to one of the tasks of Hercules. $\endgroup$
    – DWKraus
    Sep 13, 2022 at 20:59
  • 2
    $\begingroup$ It should be noted that all these answers/comments imply that the army is an army of workers trying to reduce the mountain. If all they're doing is fighting on the mountain, I believe the answer would be "no". $\endgroup$
    – jdunlop
    Sep 13, 2022 at 21:50
  • 1
    $\begingroup$ The trick is not in the digging up of the soil, the trick is in the moving of the soil somewhere else. How does the soil get moved? Just by trampling it? Someone carries it? It just gets slowly knocked over the side? $\endgroup$ Sep 13, 2022 at 21:58

3 Answers 3

7
$\begingroup$

Your mountain will flatten due to erosion long before even immortal warriors with perfectly impervious weapons of any size could possibly flatten it

Case #1:

Assuming the original top of the mountain could host 500 people in hand-to-hand combat (that's a very, very wide mountain top...) and assuming corpsmen would drag the wounded down the mountain for care leading to the healed warriors trudging up the mountain to do battle again plus space for whatever logistical stuff that all would require....

I'm guessing off the top of my head, but you'd likely need at least a diameter of 1,000 feet to pull that off. Maybe less, but that's my story and I'm sticking to it. So we have more-or-less a cylinder 1,000 feet tall and 1,000 feet wide with a volume of 3.14x109 cubic feet.

In the course of random battle, some 57 cubic feet of dirt per soldier must be removed from the mountain top each and every day for 300 years to flatten it as you require. And most of that dirt would have to be forced to the edge of the cylinder to be displaced as you require.

Well... it's the stuff of spectacular Greek mythology, but it's not believable.

Case #2:

That mountain top is a LOT more narrow. Rather than simulating it with a cylinder, we're simulating it with a cone. Your soldiers are fighting on the slopes of the mountain. They might even be tumbling to the bottom to get healing. Fewer soldiers could fit on the mountain — but just for the sake of comparison, let's say 400 soldiers can successfully fight on the slopes at any given time. The big benefit is that the dirt needn't be pushed all the way to the edge of anything. What now?

We need another guess as to the radius of the cone at its base. The height is 1,000 feet. We need a believable radius to accommodate 400 men. But let's be outrageous and say the diameter of the base is 1,000 feet. Volume = 𝜋r2(h/3) = 261,799,387 cubic feet. That's a LOT less. Now we're only dislodging about 6 cubic feet per soldier per day.

I'll be honest, it's still unbelievable and I'll mention why in a moment, but it's whomping more believable than Case #1.

Conclusion

  • First of all, it's really unlikely that the people who read your story are going to say to themselves, "wow, that's so unbelievable that I'm going to pull out my calculator and prove it wrong!" We get a lot of questions where people ask if things are plausible, realistic, or believable. 99.999% of the time the answer is, "if you write a good story, it will be." While MIT students in 1975 chanted in the halls of a scifi convention, "The Ringworld is unstable!" that's very much the exception, not the norm. Frankly, I love the idea. Ignore everything anybody here tells you and move on with your story.

  • Second, if you really do require a scientifically plausible answer. No, your situation won't work in just 300 years. It's unlikely to work in thousands of years. As @AlexP points out, there are too many variables to consider. As blood soaks the soil, it gets harder to move. Shuffling feet doesn't displace that much soil. The handful of dirt that flies away when an axe hits the ground isn't likely to fill a small glass and will return to the ground very quickly. And once the warriors are standing on rock instead of soil, it won't matter how long they fight.

And I beg you not to ignore the phrase, "it's the stuff of spectacular Greek mythology."

See that plateau, son? That's where Hercules led a thousand men into battle against the unwashed barbarians from the north. For three hundred years the battle raged! Blood drenched the mountain and you can see that today from the red color of the soil. On they fought until the very top of the mountain was worn flat from their exertions! But in the end, son, Hercules stood triumphant with the fifty that remained and praised his father Zeus for a great victory! We're here today to remember the fifty, son. I want you to be brave like the fifty! The iron mine on the other side of the mountain? Well... that's where Hercules found the ore for his weapons, of course!

$\endgroup$
3
  • $\begingroup$ 300 Spartan Hoplites, 900 other Spartans or their Perioeci and all in all somewhere between 5 and 8000 can hold a narrow between a cliff and the sea of at most 100 meters width for days. $\endgroup$
    – Trish
    Sep 15, 2022 at 8:57
  • $\begingroup$ And that means what, @Trish? The OP didn't ask how long his warriors could hold a mountain. He asked whether or not a raging battle (they're not actually trying to move the dirt) over 300 years could remove 1,000 vertical feet of dirt from it. Go climb a small rise and start kicking dirt with your feet and see how long it takes to remove one vertical inch from the top. (Where do the Spartans even come into this...?) $\endgroup$
    – JBH
    Sep 16, 2022 at 6:44
  • $\begingroup$ Assuming the original top of the mountain could host 500 people - you don't need a large area, but a narrow straight path is enough to hold that many - the battlefield of the Thermopylae was tiny but saw about 20k vs. 6k fighting. $\endgroup$
    – Trish
    Sep 16, 2022 at 9:00
4
$\begingroup$

3000 feet is about 1000 meters. 300 feet is about 100 meters.

Assuming the mountain is a cone with a height of 1000 meters and a circular base with a radius of 2000 meters. (Giving a slope angle of about 27°, for the curious.)

  • The top 300 meters of the cone have a volume of about 113 million cubic meters. Moving away 113 million cubic meters of dirt and rocks in 3 years requires moving away about 100,000 cubic meters of dirt and rock per day.

  • To make the problem tractable at the level of technology of an army using battle axes we will assume that the hill is made of some sort of clay, not actual rock like a real mountain. A very well-motivated man, using a pickaxe and a shovel, can shovel away about 3 cubic meters of clay per day and load it in a wagon. (Or maybe 2 cubic meters or even only 1 cubic meter, if the clay is hard set. Or maybe 4 cubic meters of loose loess.)

  • Overall, to shovel away 100,000 cubic meters of clay per day you need to have about 33,000 diggers. Using pickaxes and shovels, not battle axes, which would be worse than useless.

  • Then you need some 10,000 drivers to drive the wagons drawn by some 20,000 horses or oxen, to carry away the shoveled clay. And 10,000 support personnel to cook and clean for the diggers and drivers, to care for the horses or oxen and so on.

  • As the work progresses, the clay which had been shoveled and carried away from the mountain will need to be spread out over a large area, unless the mad king wants to make a less large hill near the large hill. This will increase the number of drivers and horse or oxen and support personnel.

  • Overall, yes, if the mad king is rich enough, and his country is populous enough, an army of about 70,000 to 80,000 workers can shave off the top 100 meters of the soft clay hill in 3 years. Forget about the battle axes.

  • If the task is to be done in 300 years instead of 3 years, then the size of the workforce can be reduced proportionally, so that a mere 700 to 800 workers will suffice. This becomes then a pretty ordinary long-term project.

  • If the hill is a real mountain made of rock, sorry, no way to make much progress with pre-modern technology.

Or they could use modern tools. Using modern backhoes and motor driven trucks you could do it in a few months with a few hundred workers.

$\endgroup$
3
  • $\begingroup$ The title now says 200 to 300 years. $\endgroup$ Sep 13, 2022 at 21:55
  • 3
    $\begingroup$ For completeness, there would need to be a dedicated crew to take away the manure produced by those 20000 horses or oxen plus men, else you will end up replacing the clay mountain with a more smelly one $\endgroup$
    – L.Dutch
    Sep 14, 2022 at 7:46
  • $\begingroup$ 3 cubic meters is small. If it was digging such a whole, I would agree. But when you want to remove a lot, you will be taking away layer by layer so you would be chopping clay in front of you, not underneath you. And with proper tools, things can become much faster. $\endgroup$ Sep 14, 2022 at 10:30
1
$\begingroup$

Erosion is not a viable way to make this happen, as the other answers have explained; try explosion.

If there are two warring factions on either side of this mountain, it makes strategic sense for one or both sides to want to block the path across the mountain to prevent attacks from the other side. They use gunpowder (available in medieval times) to blast portions of the rock in order to collapse it, making the terrain much harder to pass. The goal is to turn the mountain slopes into cliff faces which the enemy soldiers cannot climb without special equipment. The other side then responds with more gunpowder to blast through the cliff so they can advance.

$\endgroup$

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .