How do I enable trench warfare in a hard sci-fi setting?

Question

As stated in the title, I would like my setting to have combat akin to WW1 trench warfare. I've done my best to create systems that would enable that, such as keeping weapons and vehicles comparable to modern day and making orbital bombardment too costly or ineffective due to planetary shielding, but that still leaves a lot to be desired in terms of making sure that the style of combat I want works within my setting.

Visually it feels like this style of warfare would suit the setting perfectly, but being a mostly hard sci-fi setting it feels like there is more that can be done to rationalize it.

In regards to the settings tech level, the Expanse is just barely below the average tech available to the various factions and nations, with the exception of one faction which uses advanced energy weapons such as beams and Star Wars-like plasma bolts. Most ships are more than capable of making an edge-to-edge solar system journey, but lack FTL thanks to ancient space gates. AI is advanced but not to the point of sapience of full sentience.

In regards to the planets being fought on, the majority of them are very very Earth-like thanks to the terraforming of a now long-dead empire whose tech was lost in a galactic dark age. What few non-earthlike habitats exist are akin to the cylindrical stations from the Gundam series or the domed habitats on barrel Mars-like planets.

The nations/factions in focus come in two groups:

• A feudal empire with a focus on conscripts, power armor and mechs, utilizing heavy kinetic weaponry and explosives against a tyranid/zerg style hive mind of huge proportions.
• A stratocratic oligarchy with a heavy focus on energy weaponry and bioengineering against a Terminator-style machine network that strips planets of resources and people to be repurposed.

As to what specifically I'm looking for with the WW1 style of warfare is that claustrophobic, dirty, highly drawn-out combat with heavy cost both mentally and physically.

Answer 1

Have at least five men per meter of front line.

Trenches remain useful and widely used in the modern age of missiles, drones, and precision guided artillery. However, to get the trappings of WWI trench warfare - long, mostly static fronts of opposing layered trenchworks - you need enough men to hold that much territory, and that number, historically, is staggeringly huge. Spanning a few hundred kilometers of the Western Front took armies of millions, with some individual battles involving millions of men. The biggest reason why you don't see extended trenchworks in modern conflicts isn't modern technology, it's the fact that trench warfare is totally mobilized warfare, and modern total war is nuclear war.

Which brings us to:

It's total war, but nobody can use nukes for some reason.

You'll probably have to dip into the suspension of disbelief a little bit for this one, one way or another. Some sort of technologically themed magic nonsense would be my suggestion.

Now we have the necessary preconditions to have trenches at all, we need to make them useful, so we must:

Make area-targeting artillery the king of the battlefield, and give infantry the tools to protect it.

Infantry protects artillery from infantry. Trenches protect infantry from artillery. If artillery is king, infantry is queen, and if infantry and artillery rule the battlefield together, they have layered trenches in the front protecting artillery fortifications in the back. This means pushing down the usefulness of air power (including orbital strikes and long range missiles), precision guided munitions, and armored cavalry (tanks, etc).

We can get rid of armored cav by giving infantry man-portable direct fire artillery that can put holes in tanks. It has to be reach-out-and-touch-it weaponry of some kind, not something like a modern man-portable missile launcher, otherwise tanks will be able to beat anti-tank infantry to the punch, and will disrupt our perfect trench paradise.

Getting rid of air power is harder, since we need artillery shells, which go in the air. Maybe anti-aircraft and anti-missile missiles are crazy effective but both sides' supplies are low, so we only use them to shoot down valuable targets, not thousands of dumb shells fired by artillery.

Note that both sides need to have these capabilities, and they need to have artillery with the same effective range. If either side's artillery can kill the enemy artillery from farther away than it can shoot back, or if either side has armor or air that can punch through or over trench lines and kill the enemy artillery, you'll have guerilla or urban warfare, not trench warfare, regardless of any other factors.

Now that artillery and infantry are fighting it out with millions (maybe billions in scifi) of men and no nukes, highly effective tanks, or highly effective bombers to ruin our fun, we need to do some research about:

How actual historical trench warfare worked

The below is an extreme oversimplification by me, a non-expert!

The main mistake that fiction makes is making it seem that the defender has the advantage in trench warfare. The exact opposite is true. The reason why trench warfare is a stalemate is that winning an engagement as the attacker means occupying the enemy trench, and the enemy knows this in advance and gets to position their artillery and back-up trenches in such a way as to make their own trench a place where they can counterattack and kill you.

It evolves something like this: artillery will absolutely 100% murder the pants off your infantry if you have to cross more than a few hundred yards to get to safety, and then their infantry will murder your artillery. You dig a trench to prevent this, and their artillery can't approach too close or they'll get pounded by your artillery, so they set up their artillery just out of range of your artillery and slowly advance their own trenchworks until they can't go any closer without being killed by sorties by your infantry.

If the enemy artillery can do a decent job of suppressing your infantry, their infantry can cross the no-man's-land and murder your infantry before your artillery can kill enough of them, because a trench that the enemy is at the top of is just a grave that you dug for yourself to die in. Then they can then hide in your trench to make your artillery stop killing them.

However, their artillery has to stop shooting or else they'll just blow up their own infantry while you're hiding in your nice trench. If you can rush back to the line with your machine guns after the barrage ends, you can machine-gun all their infantry while they're crossing no-man's land. So they try to time it as close as possible, and you try to slow them down with barbed wire, interconnected fall-back trenches that you can retreat to during the barrage, and so on. However, sufficiently overwhelming and tightly timed artillery fire can give the attacker a better chance of getting there first.

You know this problem, so you dig an extra trench line behind your trench line. Inevitably, they will drive you back, but doing so will cause their infantry to advance into range of your artillery. So as soon as they finish winning the battle for your front trench line, they're in a horrible, exposed position. As soon as your infantry is ready to counter-attack, you shell the heck out of them (they hide in your trench), advance your infantry at the double (no barbed wire slowing them down behind your front line!) and your infantry murders them in your trench, re-occupies your trench, and everyone's right back where they started, except a lot of people are dead.

Answer 2

Beam Weapon Dominance:

Line-of-sight weapons have become extremely powerful and effective. Aircraft are all shot down. Missiles are all shot down. Even mortar shells and artillery shells are hit mid-air, and must be massive to avoid being vaporized or ablated & the aim thrown off. So precision in long-ranged attacks has plummeted. Beam-resistant shielding is too heavy to be practical on most ground vehicles and tanks are enormous and slow.

To hit opponents, giant artillery need to fire projectiles weighing tons. Or, conversely, the shelling must be so massively profuse as to essentially be indiscriminate.

The beam weapons are fairly fragile, however, and sit just beyond the horizon, burning anything that rises too high off the ground. They might pop up to shot really high-value targets, but otherwise remain a hidden menace.

Meanwhile, individual soldiers are armored and carry powerful but short-ranged weapons. Fighting is close, brutal, and favors those sitting behind enough loose material to absorb large-caliber guns and RPG shells. Creeping robots and engineered monsters stalk no-man's-land ready to pounce. AI-driven mines with IFF software move about into areas previously cleared of mines to wait patiently with claymore-like shaped charges.

Answer 3

This isn't as hard as it sounds. What you have to do is eliminate the reasons that trench warfare went out of style. Consider the case of naval warfare. The only real differences are that the trenches are mobile, and you can't send waves of men ship-to-ship.

First, create automated turrets that can shoot anything out of the air that isn't ballistic. This eliminates anything in the air up to a few miles, including cruise missiles. Add in Kessler Syndrome to eliminate orbital munitions.

Put your soldiers into heavy powered armor to negate chemical and biological weaponry, shrapnel, and maybe anything smaller than a 50bmg. You be the judge.

A lot of sci-fi goes all tanky at this point, but the firmness of the ground you drive on is a hard limit to the size of anything that moves. You aren't going to be able to drive your sixteen inch guns up to the front line.

This all adds up to man-scale mechanized warfare, and there's no better armor than a few meters of good old dirt. I'm sure Tony Stark would design machines that dug tunnels, but such a thing would be on the front line, by definition. Most of the war would be figuring out when the optimum time and place to have everyone hop out of their holes at once and attempt to blow up the other guys' holes.

Answer 4

Set the Battles on the Frontier

Trench warfare went away when we invented airplanes. Your world has airplanes (and spaceplanes) but not in the places the story happens. The stories take place on the frontiers. Planets with new colonies. They have advanced tech in their bases for food production, medicine, and sanitation. This covers your sci-fi setting.

The colonists also have rifles. You see many of them are rootin-tootin, red-blooded freedom-loving, red meat-eating, God-fearing, wife-beating American citizens.

Being allowed to bring a gun was part of the strategy for recruiting colonists. Many of these guns are closer to WW1 guns than modern guns with their computer chips and silicone hand grips. The colonists brought hard-wearing and primitive devices you can repair in your garage by hand.

But no one thought to bring the B52 Bombers to found the colony. They could order one from headquarters but it will take tens or hundreds of years to get here. Because it is hard sci-fi. So their wars uses more primitive tactics.

Answer 5

There are several things you need to eliminate for this to work.

Electronic guidance.

Since the long ago age of humans throwing spears at a mammoth from a cliff, humans have looked to outrange their enemy. You need to make missiles less effective, so trenches can be close to each other.

To do this, have the shield fry unshielded electronics. Dumb artillery can easily hit enemies, but most mech suits and such rely primarily on non electric insides and electronic weapons don't work that reliably.

Stationary locations are much easier to shield from interference, so trenches tend to be much more defensible.

Stop mobility being a massive advantage

Most wars aren't fought mostly in trenches because mobility is a massive edge. Make it not so.

Anti air weapons need to be much more effective than air power. The norm would be to send power armored soldiers to crush anti air before using air power.

Anti tank weapons need to be much more effective than vehicle armor. If you send a tank out without good support, it'll get smashed.

With all that you can have trench warfare.

Answer 6

Lets go from big to small.

-orbital bombardment/WMDs.

Most people on here believe that Orbital Strikes would become the norm. That would never be the case however as its just never ever a smart move.

Lets take Russia's attack on Ukraine. They could easily have started the attack by throwing a bunch of nukes on some important military targets and then rushed in. Why didnt they?

• if Russia had used nukes, everyone else will use nukes too against them (if only when they assume Russia might be aggressive towards them).

• it destroys the livingspace and people living there, forcing them to move away. Worse: if you use too many nukes (or Orbital Strikes) you may destroy the very living space across the country/planet. This is bad both for short term and long term plans as the time and cost to make it liveable and rebuild the infrastructure are massive compared to the time and cumulative resources gained from capturing and utilizing that livingspace and infrastructure (mostly) intact.

• it destroys infrastructure you might want, especially since that is what the owners will likely try to protect.

• its only real use is terror and genocidal depopulation (and perhaps as an area denial weapon)

• its costly. You may counter this with "but rocks in space are cheap". But you have to consider the fuel expenditure to nudge the right rock on the right trajectory to the right target and have it land within a reasonable timespan and the options of the defenders to detect and intercept it in time (one tiny nudge a day in advance can make it miss the planet, let alone its target).

• the ludicrous amount of targets on a planet and the amount of Rods from God or similar you need to bring across space to properly hit the targets you want, not to mention that any warfare would take that into account and hide/create fakes that you cant easily differentiate between from orbit.

• cruise missiles and other smart munitions.

If you follow modern military production you may notice that the sheer amount of tanks, aircraft and their munitions has declined rapidly. It takes a lot of effort, a lot of high tech machinery and a lot of rare resources to build and maintain them. Most of these would be used against important targets rather than a trench, and have a limited amount of them available. After the initial push by the attackers to secure a landing zone for its troops these are all relegated to just that. You arent likely to bring enough smart munitions to win a planet outright and it would take a lot of time trying to detect all the targets effectively. That means most of your ammunition will likely be produced and used on the ground and will be less advanced munitions.

• the amount of forces both teams can bring

Space travel remains a costly undertaking with your restrictions, meaning your capacity to bring heavy aircraft/tanks/munitions is going to be limited. And to bring enough forces in one go to capture a planet is going to be tough, requiring you to bring tens to hundreds of thousands of space ships (or ludicrously large ships). To take on all the military personel and equipment on an entire planet is likely going to make more than one trip of supplies and people. This means that the attackers will likely land somewhere with a limited supply and advanced equipment and dig in while they set up a production chain for less advanced tanks, aircraft and munitions while their transports go and collect the next wave.

The defenders in the meantime can stockpile more vehicles, aircraft and munitions, but have to spread them out more as they cant predict the location of the landing in advance. And they may have to content with multiple landings forcing them to keep some forces on most places. On top of that the larger stockpile will require more maintenance, so they'll likely not have too many at a time. That means for them too that they'll do the bulk of their warfare with more mass-produced less advanced equipment.

• infantry

Infantry nowadays is mostly mechanized to follow the vehicles. However with power armor you'll see a shift in how war is waged. If every infantryman can potentially carry a capable anti-tank weapon and is much more stealthy (less heat signature, less noise from the engine/actuators) then vehicles storming a trench becomes a lot less effective.

This would be a prime battlefield for trench warfare, where the top of the line equipment is just too rare and expensive to use on a bunch of infantry regularly, although it will definitely leave a mark. The attackers will ironically be the ones most on the defensive at first as they try to ship in enough men and equipment to start taking territory from the much more numerous defenders.

Answer 7

If you don't understand why trench warfare was useful and where it was successful, you haven't read Duffer's Drift (it's short and public domain).

If you want to understand why there was extensive trench warfare in WWI, read Liddell-Hart. That's long, so I'll summarize: bad translations of Clausewitz showed up in influential journals right at the turn of the century. Yes, really; it's that dumb: (In bad translation) you win by bringing force to the decisive point; the decisive point is the opponent's most important force. Artillery is the most important force, therefore you win by bringing a mass infantry charge to the artillery. Obviously wrong in several ways, and more obviously wrong with a proper translation, but actual-Clausewitz is extremely successful, so ersatz-Clausewitz had a lot of currency. However, once you are committed to a strategy that says you need to infantry-charge emplace artillery, trenches are the clear winner.

Finally, if you don't understand why trench warfare stopped, it's simple: there isn't any real reason to engage with trenches. Just go around them and do whatever you planned to do.

So, for trench warfare to actually work, the biggest thing you need is a reason to engage with the trenches.