How would the terrain of a snow-covered mountain deter a mechanized army?

Question

My story is set in a fortress town built below a mountain, and revolves around the struggle between the witch who protects the mountain and the tyrant who seeks to plunder it for resources (think Princess Mononoke) It's primarily a fantasy story with some science fiction elements thrown in, particularly the villain's army of brainwashed soldiers with laser guns and stormtrooper suits, battle tanks (reference), and vehicles for drilling, chopping down trees etc. (reference). The world is also trapped in a perpetual winter, so snowfall is pretty heavy on the mountain.

At the beginning the antagonist's forces have been trying for years to conquer the mountain, but have failed due to the harshness of the terrain and attacks from the mountain's animals and witch that protects them both. I'm having trouble coming up with all the specifics of why the mountain remains unconquered.

Questions

What aspects of mountain terrain in an eternal winter would make it hard for vehicles and footsoldiers to successfully attack/plunder the mountain?

What type of vehicle would be able to advance up a mountain that is untouched by human hands and covered in snow that never really melts?

Answer 1

Personal experience here: I was out with a group of high school students dogsledding on Wallace Lake, east of Bissett, Manitoba. We passed a Canadian Armed Forces unit on winter manoevers. They were having serious trouble with the combination of overflow (cracked ice that lets water saturate the bottom several inches of snow.

This isn't mountain terrain. It's Canadian sheield with lots of rock outcroppngs, short but very steep hills.

We were able to travel when they couldn't due to larger snowshoes, and we understood that you break a trail on snowshoes, let it set for an hour before running your dogs (who do NOT wear snowshoes) over it. So we would travel as two parties.

This is hard to apply to a military situation.

Snow, especially snow formed at very cold temperatures can be very fine and very low density. (< 1/20 that of water) It's mechanical characteristics vary with time and temperature, going from fine very fluffy to sugar snow (much like sand) to corn snow (like pea gravel) If it warms and re-freezes it can have a crust you can walk on. (One of the most painful conditions is to have no snowshoes and have snow with a crust that doesn't quite support your weight. You keep hitting your shin on the crust edge.)

Add mountains, and you have the hazards of avalanches, and snow conditions can change just by going around a corner.

You need a light attack force that is trained specifically for the conditions. You want to get them as close as possible by other means so they aren't exhausted by their trek in.

To go in with mechanized infantry essentially requires a spearhead of a combat engineering batallion to create a winter road. You will NOT achieve surprise.

For an interesting illustration look at the French Indian wars between what is now Quebec and the British in the colonies. There are interesting descriptions of trying to move cannon through the forested swamps where it takes all day to lay down a corduroy road surface and move the cannons 2 miles.

Answer 2

Historically, attacking in mountainous terrain is always difficult. The defender has advantages such as being on the high ground to observe your movements, channelizing terrain to be able to predict/control your movements and the ability to use terrain to their advantage for cover and concealment (firing upwards or trying to land artillery fire on a ridge line are very difficult to master even with modern equipment).

Extreme cold and snow simply make the problems more difficult. The Russian soldiers trying to attack Finland in the Winter War discovered that their vehicles would rapidly break down in the extreme cold, or engines that were stopped would not be able to start again as fuel and lubricants thickened and froze. Tanks did not have the mobility needed to move through deep snow or in forested terrain, hence the motorized and mechanized forces fighting the Suomussalmi–Raate battles were confined to the roads and rapidly isolated into smaller and smaller groups known as "mottis" to the Finns. Mechanized forces in the mountains will have many of the same limitations, with "motti" tactics applied by creating landslides to block portions of the road.The German Army faced similar problems on a vastly larger scale in their war with Russia.

Overall, anyone trying to fight in the mountains will be better off using light infantry formations. Specific "Alpine" or "Mountain" units have been formed in numerous armies throughout history, and generally are made of athletic troops with special training to allow them to operate in mountain terrain. They are less confined to roads, can move stealthily up ridge lines or other features to displace the enemy or gain a high tactical feature overlooking the enemy by surprise. They would use light weapons (rifles, light machine guns, mortars) and possibly be supported by special howitzers capable of high angle fire (and very experienced gunners), as well as a logistics team capable of using things like pack mules to bring supplies over inhospitable and trackless features.

So if your army has been trying to seize the mountain and resources using mechanized forces, at some point they will start dismounting troops and training them to fight in ways that are adapted to the terrain, or end up failing.

Answer 3

I see 3 main problems as the Army's General in charge of taking control of this mountain:

1. Logistics.

Mechanized/Motorized armies are heavily reliant on existing infrastructure, and supply. I'm assuming that the conditions on this mountain of yours is as harsh as those found in secluded tundras in Siberia, if so then I would imagine the horrors the Logistics Officers have to go through to keep the tanks running, and the infantry fed.

Bonus points if the Witch can summon avalanches/snow storms at will.

2. The Battle Tanks

The Battle Tanks in the images you referenced are unpractical at best, since they have legs instead of the traditional tracks. I can see a multitude of cases that can go wrong with these; from frozen joints to simply falling over due to a misstep on rocky/snowy terrain.

Plus, the "Battle Tanks" in the image are from the Anime "Ghost in the Shell", and in the Anime they were primarily used in urban areas.

3. High Altitude

You never mentioned how high the mountain is, so I assume it's well over 4000 meters tall. If that's the case your infantry would need time to acclimate to the high altitude before succumbing to illnesses and fatigue. This could even be worse if the infantry has never worked in high altitudes before (The base of operations is at the foot of the mountain). Unless your future tech can combat this; your infantry would move up the mountain at a slow pace.

Conclusion

Why is it that after years, with advanced tech, and superior fire power has the antagonist's forces not able to subdue the Witch and her animals? Because they are using the wrong tool for the job, and the generals are too tunnel visioned in a fast conquest, and the "War" has become a stalemate with neither side capable of advancing.

Answer 4

Technological Dead Zone

The only way they couldn't conquer the mountain is if their tech doesn't work. If they have battle tanks and laser cannons, they have aircraft, bombs and missiles. A witch really doesn't stand much of a chance against predator drones circling the mountain, bombing anything warm.

In the Dresden Files, magic interferes with technology causing it to fail and the more complex the tech, the more likely.

If the witch had an anti tech zone around the mountain, suddenly all the battle tanks and laser cannons will fail which means foot soldiers and simple weapons only, no bulldozers to make roads, no trucks for supplies, no planes or drones.

The bad guy would have to build a hightech base just outside the zone and then train men in archery, spears and mountain climbing. The witch's animals then stand a chance and the witch can create avalanches and blizzards to break up large groups of soldiers to make them easier to pick off.