What battlefield/tech conditions would necessitate the use of trench warfare in a modern or semi near future setting? One thing I was considering was the significant advancement of railguns/AT guns that would effectively shut down heavy armored assaults. Past a certain point the incoming shell is just coming in to hard and fast, and any added armor is going to make your tank way to slow. Combined with improved anti air capabilities it would significantly hamper the ideas of maneuver warfare, at least in theory. In the setting I'm working, satellites and space based capabilities aren't really a thing.

In fact no one on the planet has the capability to mount and operate a satellite for more than a few minutes at maximum (think autonomous anti satellite batteries in orbit that will basically intercept anything past a certain altitude).

One of the pitfalls of trench warfare in the modern era was the increased use of heavier caliber artillery and things like MLRS/rocket artillery, though at the same time close in weapons systems have been making some major progress in recent times. The combat that would be taking place would be between two peer forces, and things like nuclear weapons for the sake of argument are not a concern.

Basically what battlefield conditions would need to happen to force the concept of maneuver/high mobility warfare to grind down to a well defined front line that's just sort of stuck.

  • $\begingroup$ Your anti-satellites in orbit, are themselves satellites, and they wold therefore shoot each other down. It should be ground based installations instead. $\endgroup$ Sep 15 at 11:03
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    $\begingroup$ @MichaelMortensen they might all belong to the same people. Likely an evolution of the ones who stop gunpowder working on all those worlds where castles remain useful forever, etc. $\endgroup$ Sep 15 at 11:07
  • $\begingroup$ @MichaelMortensen so in the setting, the thing with the anti satellite cannons in orbit is that they are purposely designed to not shoot or engage at each other unless another satellite targets and fires at it; purposely designed to avoid something like Kessler Syndrome. It's kind of like a space based MAD, and given that its all automated the option to attack another satellite isn't even in the command protocols at least for now. $\endgroup$
    Sep 15 at 11:41
  • $\begingroup$ Trench warfare was possible because infantry was relatively safe in trenches. Nowadays it's much easier to kill people in an open trench than people in an armored tank. $\endgroup$
    – Alexander
    Sep 15 at 17:12

Urban warfare.

city https://mwi.usma.edu/think-army-can-avoid-fighting-megacities/


"You're seeing a massive growth right now, as we speak, of megacities," Milley said. "Today, an example of a megacity is Seoul, South Korea, with 27 million people, that has urban sprawl essentially from the [demilitarized zone] all the way south of Seoul, and it is this massive urban belt and complex."

The Army has been designed, manned, trained and equipped for the last 241 years to operate primarily in rural areas, Milley said.

"In the future, I can say with very high degrees of confidence, the American Army is probably going to be fighting in urban areas," he said. "We need to man, organize, train and equip the force for operations in urban areas, highly dense urban areas, and that's a different construct. We're not organized like that right now."

A battlefield that is a big city is a battlefield that could turn into a standoff. The linked article walks through the complexities of fighting in a city - the three dimensional terrain extending above and below ground and the masses of people. Free swinging force mobility is not possible in a big city. Megaweapons could break a standoff if you are willing to level the city and kill the civilians in it.

If you have opposing forces who are unwilling or unable to do that (or more likely one of each), then you could easily wind up with the sort of standoff you are talking about.

  • $\begingroup$ While I can see such cities being bogged down, if the lines of advance outside of the city passes it by and leaves it in a "siege" situation with limited resupply options, it seems unlikely this could cause an entire war front to bog down for an extended period. I could certainly see some Stalingrad type urban areas that are part of the front lines with each city block fought over many times, but I think it would need more than that for the war as a whole to be stalemated. $\endgroup$ Sep 15 at 13:49
  • $\begingroup$ @StuartSmith - agreed re "war as a whole". I did not take that as the OPs intent - it asks for "a well defined front line that's just sort of stuck." and having the front line in a city is a way to make it stuck. WW1 had plenty of stuck front lines and also plenty of places where the lines (if there were lines) were super mobile. $\endgroup$
    – Willk
    Sep 15 at 13:55

You have to eliminate mechanization

Trench warfare existed for the simple reason that you could not move about on the battlefield without getting instantly puréed.

Once people figured out how to do that...

enter image description here

Mark IV tank (image source)

...trench warfare's quite brief and bloody career was over.

So, if you want that to happen again, you have to set the story somewhere where there is no significant amount of armoured mechanisation.

...i.e. on an off-world colony without heavy industry

As anyone that has played Civilization knows...

...military mechanisation is a product of industrialisation and mass production. Without heavy industry, mechanised units have to be shipped in. If the units have not yet been shipped in, then the forces have to rely on whatever can be carried. Since automatic weapons can be hand-carried, the danger on puréification is real. But without armoured vehicles to move about, or go anywhere, then you have made trench warfare a possibility.

Competing colonies on Luna, Mars, Pandora, the Andromeda Galaxy, at the very start of the colonisation, where the people are waiting for the heavy stuff and the fabricators, there you can make trench warfare credible.

If you want to be absolutely sure no vehicles — or very few — get involved, make it so that all electronics in them get knocked out. Apply suitable hand-wavium here.


With fast enough and powerful enough point defenses, it may be possible to eliminate the threat of aircraft, drones, people walking around, various kinds of missile, shell and rocket, etc.

With powerful enough antitank weaponry, you might be able to render the use of armor futile, too.

For those generals and strategists who still want to be fighting wars gone past, the solution would appear to be to dig holes and hide in them, so maybe you might be able to get your trench warfare.

Personally though, I don't think that this will work very well without having other serious technological restrictions.

  • railgun launched supersonic projectiles still has the potential to overwhelm any active defensive system and penetrate a significant distance into the ground.
  • supersonic and hypersonic rocketry may also be able to evade defenses and deliver various colors and flavors of warhead.
  • small intelligent drones could evade both detection and defenses and penetrate fortifications and damage material and kill personnel in them.

None of these things are particularly farfetched, and the latter is likely to completely upend any many strategies and tactics that you might try to adapt from current or past conflicts.

In fact no one on the planet has the capability to mount and operate a satellite for more than a few minutes at maximum (think autonomous anti satellite batteries in orbit that will basically intercept anything past a certain altitude).

There's a separate question in there ("how can I prevent a planetary civilisation from reaching orbit, without otherwise interfering with them?") but you should be aware that operating antisatellite weaponry from the surface of a planet is hard but by no means impossible.

Being able to launch satellites at all implies ready access to ICBMs and various kinds of long range hypersonic and hypervelocity strike weapons, few of which can be usefully defended against by digging a hole and hiding in it. Take a leaf out of the Altered Carbon books, and have your satellite battlestations take exception to anything flying more than 100m or so above the surface.


Remember trench warfare is what happened when neither side could get the upper hand, they dug in to hold what they had and used their fortifications to launch attacks on opposition lines. To get there on the modern battlefield you need to kill both infantry unit mechanisation and airpower as decisive battlefield factors, then the frontline can bog down into trench warfare. Your idea about ubiquitous anti-armour weapons like railguns is very useful for removing mechanisation from the battlefield while not necessarily impacting it's role in supplying the battlefield. AA cover would need to be total in order to keep aircraft from upsetting the balance of arms at the front, this actually happened for a time during the Fourth Arab–Israeli War allowing the Egyptian army to maintain their beachhead on the Eastern bank of the Suez Canal.

Advanced artillery, including but not limited to squad portable mortars and rocket artillery, and missile systems are another challenge to maintaining a stalemate and are harder to explain away. If you can fire over the horizon then you can devastate enemy trenches without coming under fire and it turns into a contest of who can mass artillery fastest, and/or who can slip target acquisition teams through the lines and follow up with the most cruise, or ballistic, missiles. You'll need to work around that as well, oil shortages will go some way to explaining the lack of longrange liquid fueled missiles but they do little for shorter range solid fuel rockets or propellant based shells. You'd also get the cool mash up of troops using railguns whose batteries are charged by generators running off steam engines.


You need to make sure of a few things:

  • artillery should not have the accuracy and ammunition to hit trenches reliably. If all it takes is a spotter giving grid coordinates to artillery and an airbursting shell can clear several meters of trench its not going to work.
  • aircraft should not have the leniency and accuracy to easily hit the trenches or the support infrastructure that maintains the trenches. -a cost-effective method has to be present to deal with vehicles, without making this method the new weapon to mount on vehicles.

The biggest hurdle will be accuracy. If your opponent can pinpoint a location they can start bombing it with modern bombs and ballistics, which makes it very hard to have any static defenses. This makes railguns a problem, as they would simply have the accuracy (and range) to become the new artillery instead (and smaller ones could efficiently kill hundreds of infantry with little ammo waste). Using decoy shots you can then also sap the enemy CAS from its ammunition and then destroy any static target even without GPS. Possible solutions for that accuracy:

  • advanced electronic warfare dilutes all information over time. This makes it hard to consistently use computer data to target a specific area.
  • the war has lasted a long, looong time. Modern technology requires a lot of precious materials and worldwide processing to make, and the high-tech stuff has simply been spend. This is in part what happened in WWII, where sometimes worse tanks were designed than their predecessors because of limitations in factory space, technical know-how or resources.
  • you have effective methods to hide your trenches or make it unclear what are the "real" trenches and what are fake trenches that can be build in a day.

This would also be an effective help against modern armor, as active protections like the Trophy system will become more numerous and capable of reducing the impact of high velocity shells as well. That means the modern battlefield would devolve more to a WWII style era.

But how to truly deal with vehicles? A simple solution would be a lack of proper fuels. Battery powered vehicles have their uses but the weight of the batteries would limit the armor they can bring (ignoring the potential for super-capacitors).

There is actually a method for vehicular trench warfare. Modern tanks cant use trenches, they need a pre-prepared position they have to drive into, fire, drive back out. That driving in and out of the position takes a lot of time compared to popping up and down a trench. So multi-legged walkers could be a great tool there. You dig a massive trench for the vehicles to walk through, they raise themselves and only show their turret to take a shot and immediately pop back down again. This limits the amount of armor they need to "topside and front-facing" as they would never expose more, and any flank attack that made it to the trench would fall in and then have to deal with the tanks that cover the mechs. An additional advantage of mechs is that legs are far superior in recoil absorbtion, allowing a mech to mount a bigger gun for its weight class. The sheer size of the trenches and speed that a well-designed mech could muster would make artillery barrages tough to pull off, most would simply hit an empty trench that can be re-dug quickly.


The main thing that promoted trench warfare in WWI were the ability to move and supply a large amount of soldiers to create a solid series of lines of defense across an entire front e.g. railways, canned food, the predominance of certain weapons - machine guns firing enfilade could mow down the majority of an almost unlimited amount of enemies attacking at once, making it easy to defend even when significantly outnumbered, industrialization to mass produce the weapons/ammo needed in sufficient numbers, and no suitably advanced/developed way to reliably bypass such lines of defense that didn't end up stalemated - high profile failures like Gallipoli can also make such attempts to bypass the front lines or open new ones politically unfeasible even if they would be militarily advantageous.

So in terms of dealing with ground based hardware you would want a relatively cheap to manufacture weapon (or combination of weapons) so your defensive lines can have plenty of them, that they are easy to use (so you can arm up lots of conscripted civilians without spending an age training them), and can take out any ground units that advance rapidly, but is heavy enough or requires a short set up time before firing so it can be moved to a new defensive position relatively quickly, but it can't be used when assaulting (unless you are Jesse Ventura/Arnie), with decent fire rates so defenses can't be overwhelmed numerically very easily, and with relatively cheap and easy to produce ammunition.

Note that I don't think the literal trenches of WWI are likely in the future, something more in the elastic defense mold would seem to trump it - lots of small defensive positions that are abandoned if the enemy comes in strength with enough defense in depth to let the enemy extend themselves while giving time for a counter attack to be organized. This sort of dispersed defensive set up tends to make artillery and other forms of massed fire less effective as well.

Assuming that the next problem is to deal with other modes of bypassing these defensive lines - paratroopers and other aerial threats, and naval and amphibious attacks. In the air I think it should be feasible to create a similar stand off - with enough SAM threats on the ground in the layers of defense and enough AAM capability to rapidly move to counter a concentration of enemy air power around a developing attack you could see a stalemate where after long enough the two sides might largely stop producing bombers or close support aircraft (replacing them with more SSM launchers behind the lines to work as guided artillery instead of ASM). You could even see a scene describing the first (and only) attempt at a paratrooper drop early in the stalemate having them all wiped out before even leaving their aircraft (paralleling Gallipoli).

Depending on the location/nations involved it would also need a similar naval standoff to develop, with both sides being able to defend their supply lines and coasts, and some way to make it so the defensive side is favoured in naval battles. For example one side could be following a fleet-in-being doctrine if outnumbered (but not by too much), as long as the air defenses of the port(s) in question are solid enough (a lot of SAM sites and plenty of anti-missile defenses). Alternatively long range amphibious landings might be ruled out as too difficult to keep supplied safely for long enough to make a breakthrough, and smaller ones as being strategically useless as the defender would quickly set up a new line of defense, so the attacker would expend a lot of resources for little practical gain.

Of course such situations tend to generate lots of innovation to try to break the deadlock - taking WWI as an example the obvious one was tanks, also using planes for a myriad of roles - scouting, strafing, bombing and air supremacy, massive amphibious landing, doctrinal changes such as advancing under a creeping barrage of artillery, massive sapper operations, etc. The problem with these tends to be they take time to develop to the point they become truly effective - in this example some of them took about 20 years after learning the mistakes and improving the engineering from WWI and maybe even then a couple of years of "live fire" tests to reach their full potential.

As you suggest something like a railgun with a reasonably large battery in order to power the magnets could be an option for a weapon that is better suited to defending than attacking, especially if it has some target spotting/aim assist built in so even a novice can use it to attack any moving targets then this could act as the base for the ground side of the stalemate, and then some missile targeting advance that makes it easy to clear the skies and seas of enemies, and maybe tanks as well, without making much difference to targeting small ground targets (i.e. people in foxholes/bunkers/buildings) would do most of the rest.

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Extremely precise RailGun "AA" Bateries

In a near future Railguns have become widespread in the military, and projectile detection and fire precision have dramatically increased. As such, future AA bateries are now able to shoot 99% of airborne targets at dozens of miles away. This includes planes, satelites and artillery shells.

Without means of indirect shooting (artillery, airborne bombs, missiles) what remains is old style line-of-sight shooting, so the best defense is to stay hidden.

Welcome back Trench Warfare :-)


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