Imagine an off-world colony of maybe 100,000 people, governed at least partially locally, partially on Earth. What would the permanently assigned military for this colony look like? How would physical security, border control, coast guard (for lack of a more appropriate term), customs and immigration, security against orbital bombardment, and other concerns be addressed?

Let's say the colony is on a generally habitable planet a wormhole jump from the Solar System. There are other colonies in other star systems accessible via wormhole, in addition to much smaller mining colonies in satellite stations and on inhospitable worlds scattered through the various star systems. Faster-than-light travel is only possible via the wormholes.

The colony is 50 years old and has 3 moons. Only large political or corporate entities operate ships, as they are hugely expensive. But such entities are in competition (not war.) There are broad political tensions and wars among the major entities are not out of the question.

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    $\begingroup$ Who would be the most likely threats? If the world is at peace, you would not pay for a full-fledged military force, just for a police one. $\endgroup$ – SJuan76 Dec 3 '14 at 0:02
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    $\begingroup$ Say no threat of large scale attack from outside (that protection being provided by the Earth government(s) in the form of deep space military). The threats would consist of general crime, terrorism, sabotage, smuggling, accidents, civil unrest, and other stuff like that. $\endgroup$ – Dan L Dec 3 '14 at 0:12
  • $\begingroup$ Where are they - Earth, a moon, another planet, etc.? Also, are there other off-Earth colonies? $\endgroup$ – HDE 226868 Dec 3 '14 at 0:31
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    $\begingroup$ Hi Dan, can you edit this extra information into the question please? (Once that's done I can delete the comments). Comments are great for asking for clarification but are not a great place for people to see the information. $\endgroup$ – Tim B Dec 3 '14 at 11:16
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    $\begingroup$ Is this a colony as in a planet terraformed and colonised by humans or is it a colony in the sense of a planet with existing life that has been colonised and subjugated by humans? $\endgroup$ – glenatron Dec 4 '14 at 13:58

In a situation such as the one described and commented upon, where there are no large scale outside threats that are not already being dealt with externally, and the colony can be assumed to be a single polity, then it is unlikely that any standing military force would exist in order to secure the world.

Instead, there would be police/public safety force(s), responsible for the day-to-day threats associated with having a lot of people. Given the probable low population density and probable high technology, the crime rate would likely be quite low, and crimes would be fairly easy to solve, so the police force would be small. Border and internal security would be a police function, while search and rescue would fall under the jurisdiction of separate agencies such as a coast guard, ambulance service, fire-fighting service etc.

Should members of these non-police agencies discover a crime in progress (such as a coast guard member discovering that the boat they just boarded for a safety inspection contained contraband), they would report it to the police - they would not be likely to have the authority to investigate on their own.

  • $\begingroup$ Good point about search and rescue, ambulance, fire-fighting... the general category of "first responders" is important to my scenario as well. $\endgroup$ – Dan L Dec 3 '14 at 3:06
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    $\begingroup$ Why wouldn't the coast guard be a police force as well? $\endgroup$ – cpast Dec 3 '14 at 5:48
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    $\begingroup$ Good answer. I would only add that, since you are relatively isolated, maybe a part of the population is a police reserve force; they are not usually employed as polices/emergency wokers, but they receive training to that effect 2-4 weeks a year and could be mobilized in the effect of mass alterations (v.g. rioting). Also, maybe there is interesting to have a tiny (up to 10 members) specialist swat team. $\endgroup$ – SJuan76 Dec 3 '14 at 11:52

Your military would probably depend on the threat profile.

Lets consider the things they will definitely need.

  1. The space equivalent of the coast guard.

In fact in a colonial setting this may be the most important thing. They could handle system defence, interdiction and so on. You'd probably want to have a space-station for docking so you can hand customs, quarantine and the like.

It would also make sense to have them on patrol to handle issues in the vastness of local space - so they'd be your first lines of defence.

Unless you had "Black Ocean"/interstellar capability this essentially is your space navy ,airforce and lifeboat service

  1. You might not have a traditional military without local threats but you'd have one.

However a militia may make sense - and something like the Singaporean model of peacetime conscription feeding into both local emergency and military services would make sense. You'd be able to bolster a 'core' regular military, police and emergency force with reservists quickly, without the cost of paying and maintaining a standing army.

This militia may also be useful in dealing with things like giant alien animals or other non-traditional threats.

Considering the setting, these reservists might even own and maintain their own weapons. However, having large stocks of weapons 'in case' might be more interesting plotwise.

In an american context, you're more likely to have 'National Guard' type volunteer/part time soldiers than a traditional standing army. They'd be usefu; in handling local military issues and major policing, but it wouldn't be a very large regular force.


This is jumbled and out of order for the moment; I'll try to sort it out when I'm done.

security against orbital bombardment

Hmm, cool. If this colony is on the Moon, or another body with not much of an atmosphere, they might be at risk of being hit by something. With no atmosphere, the body has no natural defenses against an asteroid or a comet, so it would be nice for the colonists to figure out a way to avoid that sort of thing.

However, it's extremely unlikely that a person would be killed by an asteroid on Earth (I take it these numbers take into account disasters from asteroids, though I could be wrong), and the Moon is an even smaller target. Bigger targets, like Venus, Mars, and, or course, the gas giants have atmospheres, and so some objects will burn up upon entry. The odds are still slim for being hit. So it's clearly not worth it to have a large task force standing by. Also, this group wouldn't necessarily fall under the control of the military.

Air force

This would not be necessary on a body with no atmosphere because wings would be absolutely useless. Helicopter blades are also useless. Airships might not work in such a vacuum, and they would have to contend with extreme temperatures. There's a simple rule of thumb: No air, no air force.

On a planet with an atmosphere, perhaps a small air force would be used. The trouble is, as SJuan76 said, there's a good chance the world is pretty peaceful. You won't have rival nations mucking about, and so there wouldn't be any dogfights, or air-to-air combat. I suppose that airplanes (and helicopters) could be useful for strafing or bombing any rebels that dared to revolt, but I think the odds of that are slim, with such a small population.


We have a similar rule of thumb here: No liquids, no navy. You can't sail a boat on the lunar seas (pun intended). Also, if there are no rival nations, there's no point in having a navy. Again, perhaps it could be useful in knocking out any rebel bases if there's something like an ocean on the planet, but there probably won't be a rebellion happening any time soon.

Boat design would be interesting because any bodies of liquid might not contain water. If you have hydrocarbon lakes, you may not want to put in ships using exposed internal combustion engines! So you'd have to adapt your ships in some way so that there isn't a huge risk of an explosion. Anti-navy tactics would also be interesting. I'm not a chemist, but hydrocarbons are flammable, so . . .


You need a small standing army. Maybe it won't be large, because, once again, there aren't any rival nations, but you need some people with weapons to take down any attacks. There would be infantry, and probably some artillery. You might see tanks, as well. If there's air, guns won't have any problem functioning; a planet without oxygen in the air will not be suitable for guns. Phasers, anyone? Or lightsabers? Jokes aside, you might need some weapons that are unlike what we have on Earth.

Space Force

This is crucial. What's your one way off this godforsaken rock? Outer space. What happens if some outside force blockades you in (perhaps by guarding the wormhole)? You're in pretty big trouble. You might not see Luke Skywalker flying around, but you'll need a lot of spaceships guarding the wormhole and all flight paths to it. Also, if someone takes a spaceship rogue, you may need to shoot them down. Well, there is no down in space, so perhaps you're better off just blowing them up.

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    $\begingroup$ The rogue spaceship is an interesting consideration. In my particular scenario I'm having an automated cargo ship crash into a space station. What are the methods of protecting against that? Some sort of automated traffic control, IFF, and defensive system? I suppose it's a question of investment and level of perceived danger. $\endgroup$ – Dan L Dec 3 '14 at 2:42
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    $\begingroup$ Perceived danger is definitely key here. An automatic system is good because it is less susceptible to error, but it could be less mobile, and it might be slower to respond to changing circumstances. $\endgroup$ – HDE 226868 Dec 3 '14 at 2:44
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    $\begingroup$ They don't. It's a successful sabotage operation that functions as a pretext to militarize certain space operations. Kind of a political intrigue, with the first responders and local law enforcement mounting an difficult investigation that eventually leads to a scandal within the military (hence the original question) and local government. $\endgroup$ – Dan L Dec 3 '14 at 3:01
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    $\begingroup$ Hmm, that's kind of cool. . . $\endgroup$ – HDE 226868 Dec 3 '14 at 3:02
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    $\begingroup$ "The Wire" in the future in space. ;) $\endgroup$ – Dan L Dec 3 '14 at 3:03

I would say it really starts with what the expected threats are to the system. Military is not meant to police people, but to protect them from outside threats. So if there are dangerous animals or beings on the planet then you'd have a decent size army/marines force to deal with them personally.

If there were things on the ocean that might need major fire power, then you might have a small Navy, but if the colony is small there won't be a lot trading (unless there are native species to trade with) so that wouldn't likely be a priority (unless it's an archipelago that is being colonized)

Once again as far as an air force, is there any threat that they could protect the colonists from?

Immigration would be controlled by the local government, backed up by the military.

The most likely need might be for picket ships for planetary protection. The amount would depend on the expected threat level they would need protect from.


Spaceport (for wormhole ships) can be built on a moon. It will serve as a quarantine area (for sickness), holding area (no importing of plants, animals coming from other planets) less risk on home planet.

Size or number of spaceports will depend on the daily/monthly traffic (wormhole ships coming in) also depends on how rich your colony is.

Every person/cargo cleared for the planet can board registered space shuttles (which planetary patrol can scan for clearance/registration. Nothing unregistered gets past.

You can choose to add another layer of security like geostationary orbit physical inspection of registered shuttles and it's contents if you need stricter control. (Think similar to US Mexico border control but instead of cars you have shuttles and instead of asking them to pull over to the side you ask the shuttles to park in low orbit for closer scanning (if you have scanners) or physical inspection.


Most of the answers seem to assume there is no outside threat.

If the system is in relative isolation at the end of a wormhole link, then we can probably assume the only place an external threat could come from is through the wormhole itself. (For simplicity I'll assume the wormhole is relatively "fixed" in space). The threat might actually materialize in the form of political change on the home planet. The Earth might be taken by religious fanaticism, or the ideological enemies of the initial colonizing nation may have won a war on Earth, or something even more improbable happens at home, making the people on Earth see the colony as either a threat or a desirable bauble to plunder (or both).

This means that any military force would be primarily focused on defending the end of the wormhole from unwanted incursions, meaning some form of space force. A constellation of space stations, warships and remote platforms at varying distances from the wormhole would keep it under continuing surveillance, and batteries of weapons ranging from relatively slow rockets to high energy lasers, and whatever else your scenario supports, will be focused on the portal. Any spacecraft which does enter the system will have a short time to orient itself and transmit the proper IFF codes to the authorities or risk being blown out of the sky. No doubt a spaceport will also be in close proximity so the incoming spacecraft can dock and be examined by customs and security forces, in case they are carrying illegal biologicals or computer programs, or other less direct means of attacking or disrupting the planet.

Of course, the people at the other end of the wormhole will be thinking along the same lines....


The nature of the colonial military will depend on the culture(s) of the colonists.

If the colonists are from a single culture (that is not "amoral familist"), and the government is consistent with the culture's traditions, there will probably be very few internal threats. A military that can deal with external issues and threats would be sufficient.

If the culture is "amoral familist", the military will be profoundly affected. In the best case, each unit of the military will need to be either completely non-tribal, or each unit will need to be from a single tribal unit and have its hierarchy match the tribal unit. (Dune's Fremen were a successful Muslim military.) In the worst case, the military will be as ineffective as a typical Arab military.

If the culture practices out-breeding, such as requiring marriages to be between second-cousins (or even more distant relatives), then the culture is likely to be a melting pot in the long run. If the culture practices in-breeding (such as encouraging first-cousin marriages), then kinship hierarchies and tribes can be sustained for centuries.

  • $\begingroup$ It could be argued that each streich was a 'tribe' and they were brought together by liet keynes and their shared belief in the Lisan al Gaib $\endgroup$ – Journeyman Geek Dec 3 '14 at 4:53

Your scenario is too open.

The usual sense of wormhole is that it is only two ended. Who controls the other end?

If the other end is near Earth or some much larger centre, then the larger centre protects the link.

Is non-worm hole travel practical? If not, then only the worm hole needs to be protected. That is better done by the high population end.

If travel is through a chain of wormholes, with some links being in otherwise useless places, then the fostering star-nation has the obligation to patrol and maintain stations.

How expensive and time consuming is worm hole travel?

Are there aliens? E.g. Brin's "The Uplift War"

Are there competing human powers? Weber's Honorverse

Now you have a population of 100K on a planet. What is the tech level? If it's horse and wagon once landed, then most of the people are close to the landing centre. If it's anti-gravity Abbott lift and drive tech (H. Beam Piper Federation) then they will be sprinkled all over.

What's the political structure? Is it a Chartered Company (Piper again) Governor General, local council/parliament, libertarian, religious ...

100k is a small city. Typically you will need the equivalent of a police department with a few dozen constables, possibly less if the general attitude is "we make our own peace" If comparable to a Canadian city of that population, you will have about 4 murders a year. Implies another 4-12 deaths that need to be checked.

Not clear to me why you would need any armed forces other than police. You might have a militia. You might have a group that trains as volunteers to respond to other problems -- wildfire, lost kittens, zombies, rampaging moose.

For what it's worth peace time military are seldom more that 1 to 3% of the population. Assumptions behind this: Being military is a full time job. You aren't expected to grow a crop, teach high school, fix teeth, build houses too.


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