Well if you're going for a decapitation strike... most governments are in the middle of big cities.
I would argue that portals need a degree of randomness to avoid them being too powerful. The electronic signals idea is neat, and i'd like to add one of my own: Portals have inherent randomness, but more time can be taken to establish the portal to reduce this. Quick portals thus offer little warning but also little guarantee of where you end up; strategic portals are telegraphed but reliable. I would also add that portal establishing generates a detectable signal, so the quality of the warning also depends on the quality of the connection.
When it comes down to it, navigation precision ("circular error probable") is an absolutely key property of a portal system.
Millimetre precision or less? Story-Breaker Power. Metre to kilometre precision? Very useful in land war. Hundreds to thousands of kilometres? Might be useful in planetary war. Planet sized to orbit sized? More FTL than weapon system. Planetary system sized? Even FTL portal systems would be useful only for scientific observations and little more.
"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." - Richard FeynmanWell that, but it would also provide some flavor to the empire and it's conquest. Well-established planets could have pin-point precision portals pouring vast quantities of goods and troops to. But the more to the edge you get, the more the portals become incidental and the more random and variable it gets. Invasions with portals would be powerful, but hardly omnipotent if there's a degree of variability and time needed to establish them.
Similarly, i would argue portals should require exponential or even logarithmic power demands based on distance. it would enforce a system of portals connecting fairly short distances, ensuring that there is a real "distance" and dimension of depth to the empire. Opening a portal from its imperial core to it's periphery would be far from trivial, yet following a, well, road of portals takes some time and effort but would be far easier.
There’s also the benefit of if the aliens have any level of spying, they’d know the urban centers largely have unique names.
Could you imagine the pain in the nuts it would be to open a portal to a place with a commonly repeated name like say Sheep Mountain? Or something with a name that’s representing something gigantically huge like say the Mekong River or the Sahara Desert?
Pinpointing to Boston or Leeds or Moscow or similar is much easier than sorting out which Sheep Mountain to open on or where on the Mekong or Sahara.
Edited by MajorTom on Jan 14th 2025 at 2:40:55 AM
Kind of, though i would argue it's somewhat incompatible with other previous motives. It also makes earth more unique than previously, so there's more risk of the Empire taking notice and investing. Conversely though, if the cost of obtaining Earth is too high, it may also cause the Empire to back off more quickly.
Well, and also that if they do quick low-level spying through portals, the accuracy of their information may not be too high. They could probably figure out that major capitals have governments they need to attack, but if they invaded inside a city but too far away from a seat of government they may be deterred long before reaching their goal.
After all they can't be quite sure whether Earth is capable of detecting portals, so they may not want to do too much portal spying before giving away their biggest advantage.
There’s also the possibility they mistake largest cities for seats of government. In some places it’s a logical assumption, the Denver Metro Area is the largest population center of Colorado for example and is the capital. But in other circumstances it doesn’t. For example Washington DC is a small town compared to Baltimore or Richmond or Philadelphia in terms of regional population. It’s also a far cry from Los Angeles or New York City both in geography and population.
So a simple mistake in assumption could also be a reason for blunders. But the logic works if it’s correct. If the largest city by population is also the capital, it makes best sense to launch your portal based offensive right there rather than anywhere else. Decapitate the state and its largest source of defenders in one go.
This could also work with the whole electronic noise bit. They could presume that any major location with enough dense electronic activity and signals may be home to major government or institution (Banking, research, etc). After all that's why it's so active.
And as a result they don't know that it's really just because there are a lot of people with electronic devices that work off of wireless networks all living in tight spaces. They see only beacons of activity, and presume them the most logical areas to hit.
I mean, that's true more often than it isn't. Historically power follows population and most of the modern counter-examples are
1: Places where the population growth is exceeding the ability of infrastructure to keep up and impeding the government's ability to operate,
2: there are some natural or man-made limits not directly related to population causing similar issues,
3: trying to be neutral between local, regional competition or rivalries (Australia and the US fit this category)
4: Some combination of the above (Indonesia is moving its capital to a purpose built city on Sumatra ostensibly to be more central between the various provinces but also because Jakarta is getting really crowded and subsidence and sea-level rise is causing regular major flooding).
Edit: broke it up a bit for readability.
Edited by KnightofLsama on Jan 16th 2025 at 1:32:52 AM
I think there might also be an element of the aliens not being able to tell where international borders actually are. Islands are easy. Tokyo, London, Singapore, there's clear gaps there, but if they're going after North America, would they touch anywhere in Canada? They'd have to identify that there's a border there at all, they'd need to discern where it actually is and then they'd have to figure out that Toronto, Montreal and Calgary are not the national capital (and Montreal isn't the capital of anything) before hitting on Ottawa.
If they're using electrical signals, there's a not particularly low chance of them missing whole countries entirely and doing things like hitting Paris and completely ignoring everything between there and Berlin in one direction and Madrid in the other. Luxembourg, Belgium and Switzerland have pretty distinctly smaller cities than any of their neighbors. And if they're using gaps as borders, it'd be easy for them to assume that, say, Indonesia, is actually dozens of small countries.
So the Electronic Signals provides the reason for urban warfare (as the premise is built around fighting in urban environments with large enemies in biological armor), the Roman stylings provide numerous reasons as for why these invaders are coming in, in the first place. Add in some good old scifi fun and there's plenty of interesting scenarios with near future tech to use.
Excellent.
Sort of parachuting into the bottom of this discussion without context (been away for a few months), but one of the comments above reminded me of an interesting thought I had a while back, how would it work having an interstellar war with only one particular nation-state on the planet. I could see problems arising from having to distinguish which people/locations on any particular planet or whatever belonging to the group you're actually fighting and not neutral or even allied factions.
Come to think of it, this is historically a problem even in regular international conflict on Earth.
You know, the fact that the Earth is divided into hundreds of independent nation states is vastly under-utilized in alien invasion sci-fi. The only one I can think of off-hand is the Independence Day franchise. The Earth, after all, is very much not a Planet of Hats. This is especially ironic since one of the very first things any alien society would do is try to divide and conquer by setting us against each other. It would be so easy.
I'm done trying to sound smart. "Clear" is the new smart.Once again, How to Invade an Alien Planet covers this precise thing.
"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"Kind of depends on how fond humans/that planet's species are of their fellow men/species members. A lot of people who you don't want to fight might stand with their species against an alien invader, even if you were upfront about your intentions and Causus Belli, especially if you had prior dealings with that species and some manner of distrust existed. Otherwise I don't have much advice beyond sticking to targeted strikes and munitions with limited collateral damage, as stray orbital projectiles will escalate things real fast. Primarily focusing on their spaceborne assets would also help keep things cool, as I'm assuming that in order to have beef with a specific country that country must have some presence in space that ticked you off.
Clown To Clown Handshake Initiating...
Honestly, if I was doing that, I'd throw in an angle of it not working. Literally at all. But the aliens think it's working and that some humans are just immune because it turns out that there's a lot of sociopathic nutjobs in major positions who absolutely would act towards destroying the world and ruining civilization if it gets them extra money.
Because that's the case in real life.
BS. Too many people who might even consider bidding will be asking the dreaded question “okay so what’s the catch?”. Even if the aliens were airtight on what that was, there would be enough suspicion that nobody would go for it lest they be ganged up on by the rest of humanity who would then gang up on the aliens.
Or worse. Somebody will put a bid in, get the technology and immediately turn around and sell it or give it off to everyone else. Next thing the aliens know, everyone has it and turns it against them.
Edited by MajorTom on Jan 22nd 2025 at 6:40:57 AM
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Not really, something I've learned is that most people really aren't that good at long-term planning or learning from history. If invaders promised advanced technology to anyone who joins them, quite a few would do so no questions asked, and many of the ones who do have questions would still join in because the power would be too tempting. Even if not everyone accepts the alien's deal, enough would do so to cause disruptions in the overall attempts to resist them. It was a tactic used by real life colonizers, promise weapons and assistance to rival groups to weaken them as a whole.
Edited by Kaiseror on Jan 22nd 2025 at 9:42:14 AM
I still think there would be serious problems with the concept. The world wouldn't just fall over each other to get weapons in no small part because nations are quite different and the calculus would also be different.
For nations like the USA, the subservience would be an issue because the USA is already the global hegemon. They gain nothing, lose sovereignty. The risk is that an adversary may take the deal, but the issue is that credible adversaries are unlikely to also take the deal.
A country like China or Russia is authoritarian for a reason, they like to be in charge themselves. Subservience kind of defeats the point of an incredibly authoritarian CCP. Same for Putin.
For many smaller countries, the biggest issue is that taking the deal paints a target on your back from conventional threats of the rest of the world.
Lastly, the deal can obviously not be omnipotent because otherwise the aliens wouldn't be asking nicely. If they had the means to trivialize Earth's defenses they would just roll in and raise the alien flag. A deal only really makes sense if the advantage is real but somewhat modest, in which case the advantage from taking the deal isn't absolute and the option of resistance is very realistic.
Well, actually lastly is that Earth may also want to resist to obtain a better hand in negotiations. You wouldn't necessarily want to roll over immediately.
The deal is most obviously attractive to people outside of power because it gives a path to power, so sure there would be turnmoil, but it's not like the entire planet will just put up it's belly and wag it's tail.

I do like the "tracking electrical signals" explanation, as it would also allow a fun trick in which the good guys figure it out, and then basically get the whole world to shut down most of their systems and build some giant fake signal generators at locations chosen to be military staging grounds, so the good guys could fight the enemy on equal grounds and maybe launch a counterinvasion and/or nuke.
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