Which is a more effective strategic weapon/deterrent in a medieval fantasy world. A flying ship or a super gun or spellarms? [closed]

Question

The Situation

After 4 years being a baron, the empire that you are sharing a border with decides to declare war to your suzerain. It will take at least a year for them to muster their whole army and knock on the doors. You, the Baron has one year to prepare for war.

The rest of the country refuses to help you due to the elitism of country's nobility. The royal family can't help you without showing favoritism and tells you that this is a trial on how well you handle the situation. Furthermore, the nobility have decided to protect the second line of defense instead of your barony. The nobility sees you as a social climber who knows nothing and they prefer to leave you to the enemy. They see this as an occasion where you can prove yourself (how useful you can be). They will barely supply you with anything but trading activities remain open.

Your task is to delay the enemy at all cost since the country has little knowledge of war logistic. but no one said you cant stop them.

The adversary, the empire, is a regional dominant power that can muster more than a million professional soldiers of its own, 4 million levies and another 2 million mixed of professional and levy soldiers from its vast vassal states. Economy wise, they can maintain a standing army indefinitely. They also deploy land battleships with no gunpowder but with numerous ballistas and formidable magicians that serves as the battleship's main weapon. The empire is not festered by corruption and uses divide and conquer tactics to subjugate adversaries.

The baron's country is protected by mountain ranges and known for its formidable and numerous dragon knights, wyvern riders and griffin knights. The country also has many magic knight orders and a well equipped professional army of 100,000 with an additional 400,000 levy that can be called upon but the levies are very poorly equipped. They also possess the most talented magicians in the continent and are prepared to go to war at a moment's notice. Not that they will count by they must be considered to the decision as it might be, sooner or later they might be your enemies. THey are very much united under the current royal family and can't be bribed by anything.

The design objective

You have a year to prepare but the snowy winter will last for 2 months at least, which will impede your preparation for war.

You have to design something that will stop the enemy on its tracks, deter them from invading. Or if anything fails, destroy the invading army. However, if you totally destroy the invading army, the other foreign powers might seize this moment of weakness to attack. You need to sink the empire's army morale to stop them in their tracks when by using your deterrent.

Unfortunately you don't have reputation enough to scare the enemy.

But you have a resource that no one has, you are from modern day Earth.

Using that resource to full strength you realize that "Peace through Superior Firepower" fits your taste and need as diplomatic approach will either tell you to die or betray.

You come up with 3 designs of weapons that can be used as deterrent.

1. A flying ship or an airship - You've been constructing one for over a year ever since you have discovered how to make it float! But the workforce is not skilled enough to construct this wonder in time unless you dedicate all your resources there. You will need at least two for a complete military effectiveness or so you think. Logistics and maintenance of this will be very troublesome but it will be worth the trouble.

2. A Super-Gun - You know how gun works, you have mass produced it for your standing forces. The thing is, how to make a gun or in this case cannon scary enough for any threats/diplomatic relations that they'll be thinking twice before knocking on your doors again. You have a dwarven clan from the mountains that will work for you to create this cannon, but still unless you concentrate your resources on this work, it will not be completed before the war. Not to mention that you haven't tested the design and you are not even sure that you have enough resources to maintain it.

3. Prism tower Spellarms - Your fortress has the tallest tower in the known world. You can see everything in the horizon, including the invading army and the nobility army. You can cover your front, rear and flanks with these spellarms. But you've just begun studying runecrafting effect for light. You don't know how to weaponize light but you have the power issue solved because you still have a tortoise behemoth heart that you got from your adventure. You are confident that you can weaponize light but the question is will you be able to weaponize it before the imperial army knocks on your doors? To top it off it is only limited to your territory alone.

Resources

Food - You have plenty. You also have several refrigerated and vacuum warehouses: you can withstand a siege of few years, give or take.

Mineral - You have a lot since your territory is surrounded by mountains: gold, silver, copper, brass, iron and other metals. Not to mention, the discovery of an all temperature super conductor and crystalline metal that when heated makes things float. You are definitely loaded with resources but you don't have enough people to utilize the output of your mines/foundry to full effect.

Manpower - due to abundant food and work, many peasants have been relocated to your barony. However they are not enough to start your wartime manufacturing without suffering the consequences in few weeks. You have dwarven mountain clans that resides in your territory that can be coerced to work for your projects, but you need to focus on one project alone due to manpower constraints. In addition you have bought slaves to supplement your lack of manpower.

Army - You have an army of 7000 mixed troops ranging from gunpowder troops which numbers 3000, 2000 troops of well armored militia which was thought of team work and 1000 troops of skirmishers that uses lever action crossbows. Additionally, you have 1000 troops for 227 mixed battery of mortars, howitzers and cannons. These troops are better equipped than both king/queendom and imperial elite soldiers. Their morale is high and they know how to follow orders. However against the empire's million army, they probably will count for something but not victory. You simply don't have enough body to throw at the imperial army even if you enlist all of your people.

Weapons and armor - With the introduction of gunpowder weaponry, you are bound to be superior to anything you face except numbers. The introduction of new ways of manufacturing steels and other refined metals, the ease of manufacturing armor, weapons and other war and industrial components allowed you to deploy a professional army. Your weapons are better, sharper and harder than anyone in the world except spell arms and of course your gun powder weaponry, your armor is lighter, stronger and easy to procure allowing you to deploy armored troops, remotely detonated mines that can be deployed in preparation for any conflict. and lastly, your artillery batteries that allows you to pound enemies at extreme ranges with good to acceptable accuracy.

Rare/Talent resources

Magician - Just one and her main magic strength lies in healing, alchemy and runecrafting.

Yourself - you can use magic, which is limited to time-space manipulation, rune crafting and spellarms. To top it off you are a very rare male magician albeit weak but with very rare magic.

Various UAV - You have brought things from modern Earth. One of it are surveillance UAV. It will be very useful for real time intel gathering and leading artillery fire to the right place at the right time.

Your pet tyrannosaurus rex - She is intelligent short of making conversations with you. she is as big as a house and loves you like her mother.

Tri-Heart of Behemoth Tortoise - The still beating heart of a titanic monster you faced. Capable of generating huge amounts of mana indefinitely.

Shells of Behemoth Tortoise - The shell of the Tortoise you have slain a while ago. Amazingly stronger than any thing you know and super magic resistant than dragon scales.

Bones of Behemoth Tortoise - Surprisingly soft and brittle but has many uses apart from potion ingredients like can be used to ultra focus glass and make it stronger, mixed with metal to be very heat and kinetic resistant and when mixed with mercury, can be a deadly odorless aerosol.

A very large diamond - The size of a lion head. Your magician said that a very small diamond the size of a child's nail is capable of storing huge amounts of energy.

Dragon Heart - A still beating dragon heart that you manage to acquire after killing your first dragon. You realize that the mana that this heart pumps can be converted to electricity.

Objective

With the resources you have, you must achieve the following from any of the 3 designs.

• Deter ANYONE from threatening your position
• Be able to do the "Speak softly, carry the big stick" diplomatic approach
• Stop the imperial army on their tracks without totally decimating them
• prove your usefulness to the royal family.
• Not be threatened by the elite nobility of the kingdom
• positive future prospect in terms of economy, military and politics for your territory.

Which of the three designs will be the best deterrent?

Answer 1

Well, it all has to do with RATE of FIRE.

Does your airship have capabilities equivalent to the US AF AC-130, which is capable of blowing to smithereens a football-field's worth of enemy combatants every second? Most importantly can you blow enemy flyers out of the sky before they get within range?

Does your Big Bertha-like mega-canon fire at 200 km ranges and leave a 100 meter crater where the enemy general's HQ tent used to be? And then can fire again, a minute later? If it can be this precise and accurate, Big Bertha is the way to go.

Does your Spellarm tower have the capability of sustained fire? Is it a ray of death, dancing merily amidst the burning or panicked and fleeing soldiers of the enemy camp? Does lifting one's head above the trenches for a single second leave a charred stump where the soldier's head used to be? Spellarm towers it is.

Given equal rates of fire (casualties per second) the Airship has the advantage of mobility, and the disadvantage of being within line of sight. Perhaps it can be disabled by enemy mages?

Given equal rates of fire, the Big Bertha has the advantage of causing utter horror out of the blue, with no possible defense. Especially given the massed troop formations common in medieval-tech armies, this should be horrifying to enemy leaders. However, this comes with significant supply issues (must have a steady supply of 1,000-7,000 kg high-explosive rounds. Some of these are about the size of a passenger car. Not an easy ask for a rencently medieval tool-kit.

Given equal rates of fire, the ray-towers would make a traditional siege of your capitol virtually impossible, since any open structures in line of sight would be vulnerable, the most common medieval construction materials are either flammable (wood and hides), can be melted through (iron), or cannot be produced in sufficient quantities fast enough to shelter a million-man army (porcelains and baked clay). However, they are obviously immobile, so no offensive capabilities and no use beyond direct line of sight. The enemy might be seizing your mines and killing your peons, if it's around the nearby mountain, you're helpless to do anything.

All in all, if all solutions had similar killing power (casualties per second), I'd go for the airship. If you are in a defensive mind-set and worried about sieges, the light-towers will help. If you just want to rain death upon enemies within a 50 mile range and have the industrial chops to supply the shells it needs, definitely go for the mega-cannon.

Answer 2

The three options shift the power too heavily for peace to be maintained even if victory is achieved. No king will allow a province within his kingdom to have a WMD which he himself can't control (otherwise what stops you from claiming the throne yourself?!). And no empire will want a neighbor that can assert such power.

The best option for the Baron seems to be to declare Independence from the crown and declare a Swiss-style neutrality. The mountains provide a natural boarder so territorial disputes are unlikely. If trade routes close to the kingdom, then the Empire provides a new avenue. Given time, the new country could provide a pivotal trade route.

Answer 3

This is going to become an "update after receiving new information" answer, I have the feeling...

So... lets put aside the logistics necessary to provide 21 million meals a day without the technology for eatable energy bars and Cola.

One Airship? Seriously? They may take some pounding, but as soon as a lucky fireball hits it or one of that dragon-riders get cocky, its two years of development reduced to a flying target. It would need to fly at an altitude no enemy could reach, which would it make next to impossible to hit anything at the ground level if you cant shell them with HE-Artillery from up there. Maybe it can do so, but as soon as it will go down to dock at your city, its target practice for any long-range weaponry. Or imagine a bad wind blows it away from its supply-range...

Still, hoping a SINGLE super unit will provide you with an argument to not get attacked is pretty optimistic. All it needs is a silent assassin who torch that thing during peace-time.

Super Cannon? That does remind me of some WW2 Weapons. Railway-Gun Dora and Superheavy Mortar Karl. When these cuties did hit something, all that remained was a huge crater. But reloading one of these was a task that took hours. Needless to say, that the barrels did wore out pretty fast. And Accuracy? What is this?

Your super cannon should be able to hit the enemy capital from its deploying position to make any difference. Load it with some chemical agent that does burn as soon as someone put water on it and that could at least land a pretty lucky hit. And no wall from that time would resist a concrete shell with a mass of several 100 kg or even a ton.

But... even this would be an impressive weapon, it's still one. Lose it, and you are a nasty piece of rubble your million man army enemy will eat for lunch. Well, he could do this anyway, knowing that you could land at best a dozen hits, which have a good chance to do no damage at all, during the first days of the war.

Death Ray of Doom That sounds like that... uh... Archimedes Fire? There was one old geek who may have build the first laser in history using big lenses. That would be a pretty useful weapon, but all your enemy needs to do is employing sappers. Or magic. An earth wall in front of every enemy camp and all you can do is baking earthenware. They could even employ mirrors and welcome home dear death ray.

Other suggestions? What you need is something that's not a single super advantage. You said there is one year to plan ahead? Send out commandos and mine all bridges that lead to your realm from your million man enemy's point. When things got hot, blow one up and tell em that you can do this with every bridge you want.

Okay, not the best plan, but your only hope is to find something that can stop the enemy supply train without being a glass cannon type; what may fit more to that other question.

Answer 4

On how I read this, the Baron stands there with roundabout 10.000 men and 227 gunpowder artillery. The Kingdom with about 700.000 Men plus various Knight (also winged Knight on monstrous Mounts) will refuse to help even through Feudal pact?

Big Edit! More Time to think and more tactics (old answer in Spoiler)

1. Your feudal Lord refuses help, which he must provide. Therefore call a council of all lords of the king to point out that matter AND that there will be a massive invasion against your fief, which belongs to the kingdom. If the king refuses again he will risk losing support from the other lords, as they will conclude, that the king is willing to sacrifice any fief only to not get involved in that war. That thought will be incorrect as I can't believe that the Empire will stop its steamrolling after the fief of the baron (of this story).

2. Use the landscape to your advantage! The country itself is protected by mountain ranges, therefore the empire army has to use valleys and passes. Prepare them with mines, explosive charges and find out which the enemy uses first. The empire will probably take only one route despite its size and capability of using every pass to your fief. (The empire will be cocky through its tremendous army size of 7 million troops) When the army is in a pass decimate the first ranks with continuous fire with gunpowder and when ammo gets low, set off the charges to collapse the pass trapping some enemy troops and cut off reinforcements. Repeat that strategy. I suppose that the empire does not even know about gunpowder and the gunpowder weaponry, therefore the troop will be terrified by them, as with every thunder explosions and death follow (which may be very unlike to magic attacks).

3. Attack the supply routes! Use the skirmisher (or even the airship when built) to avoid the main force and attack their supplies. An armies morale stands and falls with rations. Even worse if the commanders of the empire consist mostly out of spoiled noblemen. They will insist on their luxus rations while the troops starve. Definite morale killer and a call for desertion.

Therefore the empire will halt its invasion if casualties get too high (4 times your troop size may suffice or 10 times). There won't be a need to utterly destroy the empire army as they risk to be torn apart by neighbors if they waste their 7 million men in that "insignificant" invasion.

On the superweapons: Deathray: As I understand it the prism tower works like a magic laser cannon. There I see the possibility that if it is magic it may be canceled by enemy mages. On the other hand, it is an impressive option, as it can kill everything in the line of sight (therefore I suppose everything in your fief).

I personally go for the Airship (or two or three if possible) using it to attack supply lines or rain death from above in the valley-battles. This works best if the airship flies high enough to prevent counterattacks from the ground. Then your enemy has to face a "weapon" that can attack and transport troop independent to roads ignoring water and mountains. A strategic nightmare in a medieval setting, as armies have to move to a degree on roads.

So here you go I hope this version is even clearer.

PS: The grammatic errors can be corrected as I could write this more easily in German than English.

! Point 1 as MakorDal: Force a council as the feudal pact goes both ways. Your Lord has to protect you as you have to offer support in his affairs. Additionally, if he lets your barony be squished by that tremendous enemy, there will be very little chances stopping them.
Reason:
The barony is protected by mountains. This will ensure you a bonus fighting on your land, providing possibilities of entrapping that huge army (which will move and react slowly) in passages, enabling you to rain death upon them.
Point 2:
A single Superweapon may help, but put you in Danger to be on your own alone, as your feudal lord may force you to hand it over or expel you to conquer you.
My suggestion:
-Enforce help of your feudal lord (by enforcing the feudal pact) here the airship may help greatly. With his support rally his complete army and use the winged knights to terrorize the support lines. There is the saying "an army cannot fight on empty stomach" a huge army fails as its support lines do. -Hit and Run tactics against commanders. In medieval armies, the troops rely heavily on commanding officers, without them even trained troops may falter if faced against special odds (entrapping in passages, mines, or even a superweapon like the laser)
On the superweapons:
Airship:
the IMHO best of the 3 as it is versatile, but only in more than one vehicle
Supercannon:
Useful to rain death from afar, but only as its location is secured (as this monster with push itself into the ground, see the Sturmtiger tank of WW2, it's mortar pushed it so far into the ground, that after three shots, it could no longer move)
Deathray:
second best, as some ray of death is not only deadly but also terrorizing. Best option for "talk softly and carry a big stick".

Answer 5

The way I see it, the biggest threat that you face is a prolonged siege. You could never defeat an army ten times the size of your own without a massive positional advantage, no matter how well equipped your army is. Your troops would all die of starvation before you manage to defeat half of their army.

With that many troops, they can besiege your city indefinitely, particularly if they have good supply chains to keep their army fed. However, those numbers will not count for a thing when you're inside your city walls: there is only a finite amount of space that they can attack from. The only advantage that will offer them is fresh troops, but they won't survive long enough to battle you if you have such superior firepower.

So if you won't meet them in open combat, and they cannot penetrate your city (particularly if you use that Behemoth Tortoise shell to reinforce your city gates against battering rams), then their only chance is to starve you out.

They will take their vast army and surround your city, making sure that no one can leave and no one can enter. All whilst having the benefit of free run of your country, as you will be sat behind the city walls unable to leave.

So, which of your weapons can break the siege the fastest?

The super-guns can repel any attacks on your city walls, but considering your army already has guns that can have the edge on your enemies, having better ones will not offer you too much of an advantage. If they have superior range from the city walls, the army can just move further away out of range and keep on waiting. Probably the worst option of the three.

The airships could be very useful in a prolonged siege. They could help to resupply your city, and also harry the enemy supply lines so that their army begins to starve. The logistics of keeping millions of soldiers well-fed and in fighting condition is very difficult, so any disruption to that is a benefit.

You could easily wait out the siege with this strategy, as eventually the senate/nobility of the attacker's country will realize that they're being plunged into debt by funding a war that is being dragged out for far too long. The army will get called home, and you will have succeeded in your mission.

The problem with this is that whilst you are waiting for the army to leave, enemy soldiers will be left to pillage your country, especially if they're sitting around bored and hungry thanks to you making sure they are ill-stocked with your airships. So you would win, but at a great cost.

In addition, if you were going to use the airships to attack the army, they would need to stay well out of the range of the ballistae, magicians and other siege weaponry that the enemy has. If you only have 2 airships, you cannot afford to lose one, so would need to be extra careful. This means that any weapons you could use from them would be out of range, and anything you could drop on them would be from too great a height, they would simply move out of the way.

So airships would would ensure victory, but we can do better.

The best thing that you can do is to build your mega death-ray tower. You can fire at the waiting army from a great range, which they will not be able to avoid. Wherever the army is stationed whilst besieging your city, they will be constantly being attacked.

Let's say that the beams of death are only able to attack a dozen or so people at a time, and it can only fire one charge per day as it requires energy from the sun to be stored within the giant diamond, you will only be killing a handful of people at a time. This is a drop in the ocean in terms of numbers for the enemy.

The advantage you have is that the enemy army don't have any idea which dozen people will be incinerated. You fire into their ranks indiscriminately, and they will be constantly on edge, never knowing from one day to the next who will survive.

Add onto this attacking them occasionally with the chemical weapons that you possess manufactured from the Behemoth Tortoise bones, and this adds in an extra element of concern for them. You may still only kill a couple of hundred of them at a time, but they will constantly be in fear of their eyeballs melting in their skull.

Then you can send out small strike teams on night time raids to attack individual encampments. Your men and women know your country better than they ever could, so they can sneak upon the enemy in darkness, and before they can react to the slaughter, your people will have returned behind the city walls, ensuring that no other encampments will ever sleep soundly at night.

Trying to keep order within the ranks of the enemy army will become a nightmare. They will all be on edge, sleep deprived, in fear of death and missing home. And once the horror stories reach others throughout the army, and the families back home, there will be more deserters of their army than you could ever hope to defeat with any of the weaponry you can build.

Therefore, using guerrilla tactics and terrorism, you can allow their army to defeat themselves using the prism tower.

Answer 6

The feodal contract goes both way : you help your sire, he protects you. In this case, by throwing you to the wolves, he has already betrayed you.
You know it.
He knows it.
All of his vassals know it.

You build the Airship... get it to his capital and force him to held a conclave of the high lords of the realm. (Most kingdom had poweful nobles whose power rivaled the ruler, especialy if they banded together.) If it's not possible, join the Empire.

Answer 7

Either surrender, or play Moscow. These are your only 2 real options.

If your overlord won't support you, a single weapon isn't going to do much against an overwhelming opponent. Classically, what has worked is lots of cheap weapons that cause disproportionate damage (e.g., fireships vs Spanish Armada).

If delaying the enemy is all you want to do, destroy all means of crossing the mountains, or at least make it extremely difficult. You won't STOP a determined invader, you will make them wonder if it's worth it.

Your only chance of VICTORY is to starve them out (Moscow). Destroy the passes, withdraw all food and supplies behind your capital, damage the roads, destroy signposts, leave incorrect maps and wait for winter. If possible, use raiders to attack their supplies and foraging parties.

Your ruler is not to be trusted, as he has already proved. A doomsday weapon will result in demands to hand it over followed by another war, assassins or simply by you being told to report to court, ALONE.

Edit: On re-reading the question, you have massive technological superiority already. It makes far more sense to focus build up your army instead on doomsday weapons. Save those for the next war.

Answer 8

mines.

lots of mines.

not the fanciest option, but it can do the job better than your weapon.

1. great chance of success
   since your country is surrounded by mountain, and the enemy have land-ship to move around, it quite safe to say the invasion route will be pretty much fixed. that mean the enemy will have to walk pass your traps if they want to advance.
2. easy to carry
   well, much easier than carry a big cannon. that allow you to plant them in unexpected place, like a bridge inside enemy's territory, a supply storage, etc.. also, since you dont need many people to plant a mine, you could send many team to simply littering the country with land mines.
3. hard to avoid
   without any metal detector, the only way to find mine is either: a. dig up every road ahead and b. send a guy to "check". if they choose a. , you can always re-mine a clear route and they will have to dig it up again. if they choose b. , mix anti-personnel mine with anti-landship one and let them figure out themselve.
4. multipurpose
   when not busy blowing up people and things, mine can be used for many other purposes. they can be used to creat landslide or avalanche, to make boulder to block a road etc.
5. and the most important..
   losing a few mines dont have any significant setback for you, while losing your single superweapon is an instant gameover. heck, if your can place your plant behind the 2nd line of defense, then you can keep going even after your barony has been overruned.

on the noteside: i think the best detention is to focus in the enemy's most pride unit, or the costliest one. if their land ship is the symbol of power, then focus in destroy them. it's not only demoralize, but also make the war become less cost-effective.
also, the object should focus in weaken the enemy and make them vulnerable again other empires, rather than in defeat or stop them on track; just show them that whatever they got from you is not worth the risk for it.

Answer 9

Considering given three options and objectives, they seem to be more about way of playing your cards than actual hand you have.

As for weaponry, to not mimic already given answers, there is one more interesting trick to the Prism tower, which may make it more appealing.

When firing high energy ray with right frequency you may bounce it from higher levels of atmosphere drastically increasing it's range and allowing you to smite any target. If you don't want to abandon idea of laser you can still use plasma mirroring (needs very short laser impulses lasting femtoseconds) to achieve the same.

Whether your protagonist is able to kill all the intruders or just dozen of them, with that trick he may be able turn rulership (and/or capital) of enemy into fine dust and come victorious without overkill. Moreover even if he'll die (even just temporary and only in general opinion) before the news will make it to the army as they will plunder his land (possibly even start further invasion if flow of information will be too slow, question if mages cannot send such an important messages), it's still technical win. What's more important it will probably appeal to the court as it wouldn't make him look dangerous and the king will be obliged to honor his bravery and luck (which will be the more generous, the less destruction will be caused upon king's country).

Effectively it may cover most of your points, except domain devastation and loss of the subjects already under his rule. However it would be probably the best scenario which includes actual attack of an imperial army and virtually no support from other nobles.

For plasma mirroring option, it makes quite terrifying idea of stationary offense. One that will need only solid surfaces to perform extended range attack. Also brutal power of impulse needed to create plasma mirror may be directed even from aerial object like balloons with some solid attachments. What's even more fascinating, with precise control over laser it will be possible to adjust plasma mirror to reflect the beam in expected direction, which will effectively force enemy army to hide under mirrors, allow for attacks on supplies and affect enemy morale. The beauty of this solution connects with facts that ceiling mirrors can become artillery targets, or beam may be changed into some other radiation, like microwaves or X-rays (which should prove more effective as mages may not know how it works).

Mark that the real problem will start IF your character will WIN the actual battle, against the odds sourcing from significant difference in numbers.

Why would that happen?

Even if he would try really hard, with magic on both sides (guessing from disproportions imperials may mobilize much more mages) chances are very low.

In world that studied magic, most probably both military and civilian geomancers would likely have some spells useful for mining (e.g. to make underground passages below walls), securing passage thorough swamps and creating one. Whether they would find any underground explosives, they would make sure to sink potential mines and/or seal them in rocks which would slow the army. Eventually they obviously have detection spells for detection of mineral ores which would make their task trivial. Also probably there are spells used for scouting and hiding.

To make the point, as long as protagonist will not use unthinkable (by imperial standards) or imperial army is not lead by incompetent idiots/rushed by arrogant dreadful ruler/never actually fought/has no exploitable beliefs, it is very unlikely that your protagonist will actually deter invaders. If mages are able to assure great harvests, probably they are also able to reconstruct destroyed bridges, at last when working together.

Then objectives would not be achieved with battle but during it's aftermath.

Device able to destroy such an army would be surely branded as doomsday weapon, as it sounds like Prism Tower magic is uncommon to protagonist's world.

To lessen the fear of his power he'll most probably have to lie about output or activity of the Tower (like claiming it's power source exploded or creator of the spell died heroically to power it as nobody could prove you wrong without "power source" or knowing the inventor) and other parties will likely try to get closer to him to know what the truth is and use gained position to own benefit.

All of the world powers will try to secure control over the Weapon. Depending on protagonist's relations with royalty he may be pardoned, but no ruler would allow for his subjects to posses doomsday device even if for greatest friend. Even if they would make an exception, they still would have to react on issue or risk showing supposedly weakness in eyes of nobles. Exact reaction of the king and his court will heavily depend on circumstances you create.

Saying so, your protagonist would make a bothersome royal friend. As the one who defended the country from sure doom may easily be viewed as a war hero and better candidate for crown than a coward king (as ruler would be surely called behind his back in such a case at least by a few new "friends" of protagonist), so probably your protagonist would be forced (with differing courtesy) to marry into royalty or declare own rule over his domain as neutral (which probably nobody would deny at this point, mind the doomsday device) which will bring him into area of international politics.

In case of political marriage your protagonist would cover most of goals, except for avoiding decimation of invading army and being drawn into court politics which I presume is not something he wishes for.

Assuming your Prism Tower will provide enough kill rate, your protagonist should expect that he will be threatened by mages as they are probably the only ones who can destroy his tower.

For the finishing touch, even if your protagonist would declare independent rule over his domain, he would be pestered by agents of other countries till his death/assassination/moment somebody else reinvents Prism Tower (which may be proved impossible due to need of immensely powerful mana input from Tri-Heart and gathering of sunlight).

I hope it answers intention behind this question.

Answer 10

I'm going to ignore any diplomatic moves and focus totally on the weaponry/innovations that could be sufficiently called a 'big stick'. It's difficult to say if these are effective without knowing more about the magic system but the effects of raw mana on an unprotected body would seem to be devastating (as they generally tend to be in fantasy), with mutation, mutilation or just getting exploded being the main effect.

I quite like the idea of the cannon, though it's a mechanical nightmare and might not really function, I think it's ability to be protected vs it's range (and it's disregard for line of sight) could make it a potent weapon. Here's the plan: Create two, smaller lighter cannons with a focus on muzzle velocity instead of direct payload size. This might not be needed, wouldn't mind feedback. I just don't think one basket is the best egg carrier.

Empty the massive diamond and shatter it into >child head size bits (I assume child's head is an imperialist measurement state like hogs head).

Create shells for these new cannons with a large amount of your discovered hover metal within them.

Charge the diamond with the tri-heart and find a reliable solution to break them (perhaps a fragment of tortoise shell).

Load it all into your new cannon rounds. With the tip of shell pushing against the highly charged mana diamond. Perhaps seal with bits of tortoise shell to prevent magical discharge or interception by enemy magicians. Perhaps perhaps, place a rune of seeking or some such on the shell to assist with target allocation (or any other handy resistance, smiting or penetration rune).

Load your new Diamond Fire shells into your cannons and conduct some range testing with your UAV to confirm hits and gauge range.

When fired, the gunpowder and friction of the discharge should hear the projectile to possibly hundreds of degrees (depending on power composition). This will cause an already fast projectile to gain altitude very quickly and easily, vastly increasing the range on the device (especially if rifled or flight fitted). When impacting, the tortoise shell fragment with shatter the diamond, causing a catastrophic mana containment failure which in turn should (hopefully) remove a large section of map as well as any people unlucky enough to be within X m/km (I was angling for a magical Nuke).

The UAV sighting of high profile targets as well as any magical guidance that can be included would make this a fearsome weapon. The accuracy and power of which should only require one or two shots to bring serious political discussion to the table.

Answer 11

As far as a deterrent is concerned, your flying ship is the best bet. Here's why - To deter your enemy you must conclusively prove that you have the means to utterly destroy them if they try to attack you. It's not enough to be able to withstand a siege or be unbeatable, they'll keep trying to find ways to beat you unless they are sufficiently afraid of a decisive attack by you.

Below is the comparison -

1. Prism tower - It's primarily a defensive weapon. Your enemies can keep their armies out of range and there's nothing you can do. They'll keep testing it and will eventually find ways to sabotage/block it.

2. The big gun - It can work as an offensive weapon but that'll require taking it out of your walls. Then hauling it all over the place is too risky. You can potentially use your space/time magic to move it quickly but you can't hide it. The enemy will eventually capture it and try to use it against you. If you keep it inside, then it's worse than the prism tower.

3. Flying ship - This is the most versatile of all. It can attack, defend and work as transport/supply. Armor it with the tortoise shell, use your space/time magic to move it instantaneously, arm it with your explosives and it'll become something that can attack anywhere without enemy being able to touch it. Now go kill a small but well defended village deep inside enemy territory or kill the enemy generals if they deploy and make it clear that the next target could be enemy's Capitol.

How it works -

1. Tortoise shell & Mage's alchemy/rune crafting for defense - I'm assuming this tortoise shell is basically vibranium (nothing can break it), so no enemy attacks can penetrate it. Your Mage remains onboard to ensure any other type of damages are immediately repaired and runes are working as expected. The enemy can just watch in despair as their most powerful attacks are either unable to reach or deflected.

2. Your space/time magic for travel - You manipulate the time/space around it so that it covers more distance in less time. Simply contracting the space between the ship and its destination may achieve it. Now you can arrive pretty much unnoticed wherever you want. Travel as high as possible and then drop down to deliver the payload accurately and then fly back up again. Then "appear" 50 miles south in a matter of minutes and do the same trick again. You may or may not be able to do this over the Capitol but they don't know that. Also, you can potentially create smaller versions of the prism tower to install on your ship. You can use that prism tower for aiming from very high up above the clouds before dropping the bombs!

3. Bigger bombs for shock and awe - You have the technology to create bombs that the enemy has never seen before and you have a delivery method that no enemy can counter/block. Use your drones intelligently to keep track of enemy movements pretty much everywhere at all times. You can effectively destroy the entirety of enemy leadership in one blow with careful surveillance and planning.

4. Preemptive strikes and warning strikes - if things flare up, you can either decimate a strongly fortified enemy base well inside enemy's territory to demonstrate your secret super weapon or wait for them to deploy and then kill the entire leadership of the army. You're effectively telling them that next will be their king's palace. That'll force them to stop and reconsider. They'll still try by less overt means but that's a different question.

Answer 12

TL;DR -- Get the airship, yo

I like this detailed scenario! Let's dig in...

Assumptions

• You mentioned the enemy has powerful land forces, but didn't list any air units for him. Assuming he has none.

• Assuming your guns are primitive muskets; take 30 seconds to reload

First Approach -- Wind

Have you talked with the Empire guys? Why do they want to invade anyway? First move should be to find out what they want; it might be possible to dissuade them, or figure out a way for them to get their objectives without fighting.

Really, a large empire should be happy to have a strong mountain border... one less thing for them to worry about.

They might want a simple border adjustment ... put the border halfway through the passes so they can have forts, too. We could work with this.

They might want access to something which is in your territory ... trade routes, diamond mines, or the like. If this is what they want, you may be able to buy them off with tribute. King will be annoyed, but he's got precious little moral high ground.

They might want to annex your barony or your whole kingdom. If they just want your barony, maybe you can make a deal, become an Imperial governor, and have those million men protecting you! ;D

Might be an ambitious prince or general wants to gain reknown for internal political reasons. Could you ... guide him to attack someone else?

Okay, 'nuffa dat. Let's assume they are hell-bent on conquering the entire Kingdom.

Second Approach -- Ether

Per above, they seem to lack aerial units. You might be able to stage aerial raids into their turf with dragons and airship. Disrupt their supply depots. Destroy bridges on roads leading toward your land. Try to delay them until winter, when it becomes impossible to move troops through the mountains.

You're showing them that you have weapons that they just can't answer. You strike, then fade away like a ghost. Might be enough to stop the invasion, or delay it long enough for your King to wise up and send support, or heck, the horse may learn to sing.

Third Approach -- Earth

Your best asset is that mountain range. There are a limited number of passes they can use to attack you, meaning that (a) they have to funnel through that area, and (b) they can't overwhelm you with a full-border attack.

Fortify your passes. Get your dwarves to build successive defensive walls every mile or so. Make it prohibitively expensive to carry through to your fat, helpless lowlands. Drop bombs on clustered troops from air assets.

Make sure to contest the high ground above the passes. Your men can roll rocks down on the foe. With enough magic/gunpowder you may be able to provoke avalanches!

Stopping them in the passes is your best hope of victory. Try real hard here. If they do make it to the lowlands, the sunk-cost fallacy will drag things out longer than you'd like.

Fourth Approach -- Water

We've just seen how you do well at bottleneck locations. Find more. You'd be surprised how few stretches of land are suitable for moving huge armies. If the Imperials break through to the lowlands, contest fords and stretches between forests/swamps. Do not engage in set-piece battle; you'll lose. You are the water; you dance away from their embrace.

Bleed them at every bottleneck, then flow away. Consider training dragoons (ride to battle, dismount to fight, ride away). Not dragons, dragoons. ;D

Don't forget to engage your contingency plans; you want to evacuate as many civilians (and their livestock and food) as possible well in front of the enemy advance. Leave nothing valuable behind. Especially food.

Leave mounted units behind enemy lines; their job is to harass communications and disrupt supply trains. This is critical. If the enemy can't feed his army, he must leave or surrender.

Remember, you have total control of the air. You can find supply caravans. You can watch the maneuvers of his army. This is a huge advantage.

Also ... focus on his landships. You want them dead before the next phase.

Fifth Approach -- Fire

Let's say the enemy grinds through all this. Maybe they get lucky and shoot down your airship. They debouche into the plains near your baronial capital. You're about to teach them a new concept. It's called ... rate of fire.

It's way easier/faster to train a musketman than an archer. Every footsoldier you have is a rifleman. Group your men into 4 sections, each of which fires in a coordinated volley while the others reload. If you have 10,000 soldiers left, you send a volley of 2500 bullets every (30/4) 7.5 seconds. This has an unsalubrious effect on massed infantry.

I don't think any non-gunpowder army can take this for long without breaking.

Sixth Approach -- Defeat

Let's say it still doesn't work. The enemy is disciplined enough to soak up the ruinous casualties and routs your men. Take your survivors and flee to the kingdom proper, leaving the battered enemy in a foodless wasteland. If practical, make one last attempt to blow the passes.

You've had observers with you, so word of your savage defense has spread. You've sent tutors to all your allies, teaching them the secrets of gunpowder. Your defense has given the rest of the kingdom time to mobilize and assimilate the lessons of the fighting.

Remember you are just one barony in a much larger kingdom. You have a lot of friends. Friends with guns. And they are pissed.

Time for the counterattack. But hey, that's another day.

Answer 13

Contrary to most answers, so far, I think this is going to be easy.

First off, being surrounded by mountains is already an insanely awesome defensive advantage. Mountain passes make it so that a few determined defenders can swing way above their weight class. Factor in that your army is better-equipped (more magic and gunpowder,) has night vision scouts (UAV's,) and you probably don't even need a super weapon to defend your territory.

But, you can build a superweapon, so why not? My #1 choice depends on the details of your mountain passes. IF there is a location you could put the giant cannon so that it could hit all major mountain passes, then go with the cannon. You don't have to spend energy on mobility, so it'll probably be stronger. If not, then go with the airship.

Your strategy: position decently-sized forces at mountain passes, use UAV's to identify enemy incursions, and then use the super weapon to annihilate them once they've fed a few thousand troops in. Finally, maintain a mobile reserve and remain vigilant for the use of minor passes and commando infiltrations over otherwise impassable terrain. Even if the enemy actually punches through, you can still contain them by obliterating their supply trains and reinforcements with the super weapon and then crushing the troops trapped within your realm.

Goals met:

• deter anyone = how about "defeat anyone"? No one can beat you.
• speak softly = your advantage evaporates outside of your mountain passes, so nobody is going to feel overly-threatened
• stop the army without decimating them = mountain passes will restrict the number of enemy troops that can invade at any one time (get blown up by your super weapon at one time), so you're good here
• prove your usefulness = You'll win, so I hope that's enough here
• not be threatened by the elite nobility = it will be harder, but the mountains should serve you well even against similarly-equipped forces
• positive future prospect = maintaining one airship/cannon won't be too expensive, and you should be able to find at least one trustworthy person to captain it without worrying about a coup.

Historially, the weakness of mountain pass defenders is the fact that their own country and allies neglect to reinforce and resupply them or the enemy goes around them. Since you are surrounded by mountains and appear to be quite stable and dedicated, these weaknesses are not yours.

Answer 14

I tentatively suggest that you can at least hold them off as long as you like.

you can use magic, which is limited to time-space manipulation.

A gradual increase in the local gravity field as they approach will render their efforts more and more wasteful to the point where they cannot continue further.

Calibrate this to a desired 'distance from capital', then unleash with a mix of the other answers people might come up with?

...I reckon the approach would exhaust them long before then. To compliment, you can sweep them with microwaves (as light) from the top of the tower using the big diamond-thing and some sort of modulating setup. (details elusive). Amplify accordingly using various tortoise body-parts and they will be sufficiently deterred long after the burning sensation stops them even facing front.

The deterrent may emerge on its own after a wasted generation of approaching forces realise they've become sterile.

Answer 15

Airship. Everyone is looking at it wrong. An airship or two is not going to be enough to be militarily effective given the size of the forces. While it could do nasty things to ground troops it can't be in enough places to win the war.

What it can do is fly high and bombard enemy cities. Fly over their capital, toss out a big load of stones, along with a note (many copies to be sure they actually get one)

"If you do not immediately cease your attack upon my nation your cities will be put to the torch one by one. You have no weapon that can reach high enough to harm this airship and we have supply caches sufficient to burn your empire to the ground even if our lands should fall."