In a story a long time ago in an age long forgotten, the main characters find an ancient portal-gate-system, powered by an even more forgotten magic.

The main characters have access to soldiers, within a reasonable limit, within a fantasy / medieval setting.

How would our characters proceed with the exploration?

  • Magic is not gone but generally forgotten. So no scrying spells.
  • Matter only appears on the other side as soon as everything has been de-materialized, so no poking a stick through.
  • The gateway is roughly "stargate size", so a horse mounted warrior can ride through it. A rhino or elephant rider cannot.
  • None of the other gates are off-world.  They are either in the same world / continent, or destroyed.
  • If the receiver gate is gone, the sender gate "connects" but the transmitted matter ends up everywhere as scattered matter (on atomic level?).
  • If the receiver gate is covered, inside the earth, debris, the sender gate connects but the transmitted matter is fused with whatever is on the other side (or perhaps scattered somewhat evenly between the gates).

Each portal is a physical gate, appearing inside a gate room, with no possible way to move it without breaking it (it is old).

  • $\begingroup$ Do the portals only transport to other portals in your world/planet or is it literally like the stargate and go to many different world's? $\endgroup$ Sep 26, 2016 at 17:26
  • $\begingroup$ it is in the same world / continent. $\endgroup$ Sep 26, 2016 at 18:20
  • $\begingroup$ what happens in the last case (receiver gate is covered) and a lot of matter is sent through, sure it would fuse but if it was a lot of mass wouldn't it cause an explosion on the other side. "Dial the enemy gate and channel the lava flow through our gate" $\endgroup$ Sep 28, 2016 at 0:03
  • $\begingroup$ @sdrawkcabdear the gate system is old, and fragile, the gates are very far from indestructible, when the large amount of matter fuses the reciever gate would eventually break. The matter from the lava would be scattered somewhat evenly between the gates, lets say you throw a 1 liter water bucket in to the gate and the receiver gate is supposedly 100 km away but it isn't the 1 liter would be divided evenly over 100 km as atomic vapor meaning 1 cl matter per km or 0,01 ml per meter $\endgroup$ Sep 28, 2016 at 7:21
  • $\begingroup$ about 3.3455555221×10^20 atoms per meter $\endgroup$ Sep 28, 2016 at 7:25

4 Answers 4


In the cultural context you describe, this would be handled much like a forlorn hope party. A small group would volunteer, against the promise of rich rewards if they survive, or a group of criminals would be offered a pardon if they survived. They'd go through and try to return immediately with a report of the conditions on the other side.

If none of them came back, you'd try another route. If any come back, they are carefully questioned about conditions, and an appropriate party is formed and equipped for the mission. The forlorn hope survivors are kept from leaving, politely but definitely, until it's clear that their report was actually accurate. If it wasn't, the penalties would be medieval.

  • $\begingroup$ how do one prevent the criminals from parting with supposedly enemies on the other side, or just staying there barricading the gate, knowing that if they don't return none will try again ? $\endgroup$ Sep 26, 2016 at 14:54
  • 2
    $\begingroup$ @Magic-Mouse There's a term for that; 'banishment,' and it has been historically done as a punishment. Assuming the government doesn't equip them with supplies to start a new life (tools, raw resources, livestock) they're not going to do well in the wilderness, and if it's urban on the other side the culture clash will still leave the pardon as the more favorable option. $\endgroup$
    – Ranger
    Sep 26, 2016 at 15:07

Expanding on John Dallman's answer, there would be several phases to this.

Discovery – Where the network is first found and efforts are made to understand what the portals do and how they work. How this unfolds will largely be driven by the personalities of the people who found it.

Securing – Inevitably, access to a nearly instantaneous, long-distance form of travel would be economically invaluable, especially if it is highly reliable with securing and maintaining the portal sites. Fortifications would likely be set up around known portal sites by whatever social power got to it first, and if civilians are allowed to use it (for a modest fee of course), local communities would spring up around the portal sites. These cities would become major trade locations and points of enormous economical power. The ability to instantly move troops (particularly highly trained special ops tasks forces in this case) would also make these sites highly valuable military assets as well.

Long Term – Depending on whether the securing phase went on a economic, military, or hybrid route would affect how things develop here.

Economy – With an economic focus, people would flood to these gate locations. More people means more expansion, and more and more efforts will be made to expand the local cities and explore the surrounding areas for useful resources. Paths would also be made to make it easier to get to these locations. Aside from the rapid transport of supplies, the fact that the portals are pre-made and unmovable would limit major exploration to the areas around existing portals (but the portals can grant access to lands/areas too dangerous to reach/explore otherwise).

Military – The ability to move troops and supplies great distances quickly would mean that the first group with expansion power to get their hands on one of these portals would quickly be able to gain footholds everywhere there is a portal. With lots of small colonies, they would be able to expand their empire faster than anyone else, and be able to defend larger areas with fewer troops. More territory will also mean more resources, making this faction economically well off. And unless there are large areas the portals don't connect to for a resistance to hold onto, the portal faction will likely become a superpower, overwhelming all opposition with their accumulated wealth/overwhelming numbers.

The above assumes that the gate is perfectly safe if you secure and maintain both sides of the gate. If there is even a 0.5% chance of failure (randomly disintegrating what it transports, because it's old), this would kill the military aspect as the failure rate would become a "portal tax", and repeated use by an army would decimate it.


Continuing from Tezra's answer which continued from John Dallman's answer.

Your empire could set up a portal messenger service once established connections with other portals had been found.

The ability to quickly inform different cities/parties about a raid/invasion in another area of the empire would allow for quicker reaction times.

If the enemy was unaware of these portals they would be surprised when their surprise invasion didn't yield the expected results. The empire with the portals could either meet them on the field with a well prepared army or send some special ops teams with fast horses to delay them with guerilla tactics while the main army is called up/deployed.

If the enemy is aware of the portals, aside from trying to take control of a portal city, they could actually take advantage of the empires 'tech'.

They could make a show of preparing to attack/invade from one location. This information is then sent to the empires central command via portal messenger and they make the associated defensive countermeasure.. Only to find that the main invasion is coming from somewhere else. Very much like the false information spread to the Germans before D-day in Normandy during WW2.

If the enemy does succeed in capturing the portal city they could block off the portal and kill off any reinforcements coming through. Or they could attempt to use the portal themselves to sneak soldiers behind enemy lines to quietly spy/sabotage other portal cities in the network.

If the enemy can find a portal that the empire is unaware of and get their hands on the dial up sequence for the empires gates...surprise raiding parties inside the empires strongholds!

Etc etc it goes on and on.

With the danger of never knowing when a gate had been blocked off, even your own gates, I think a procedure for informing the home portal should be set up. Eg if a group is sent through the gate, no reinforcements should be sent through until one of the first party returns. For established portals where you believe it is safe, there should be a regular check in sending back an all clear message. Either daily or every few hours. It all depends on how much energy your magic portals require and how frequently they can be switched from send and receive. (matter only travels one way?)

  • $\begingroup$ Etc. etc. it goes on and on: for example, gate locations would be protected against siege (unless the enemy had the resources to lay siege to all the gate locations), because you’d be able get supplies through the gates.  (This would also be puzzling to an adversary that was unaware of the gates.) $\endgroup$ Oct 16, 2016 at 19:46
  • $\begingroup$ @PeregrineRook, I can't tell if you agree with my answer or not. As far as I could make it out, the gates are fixed in place and that a city/small area would only have one gate. The city would be protected against siege if the gate was still in the hands of the defenders. But if the defenders lost the gate to sabotage, surprise attack before a message could get through the gate asking for reinforcements...the gate and the city could fall. It would take a lot of planning and strategy. the invaders, will almost certainly know about the gate. unless a pure fluke happened. unlucky defenders... $\endgroup$ Oct 18, 2016 at 22:41
  • $\begingroup$ I agree with your answer; that’s why I’m tacking on to it.  Since your answer refers to the existence of an “empire” (suggesting that one political/military entity controls many, if not all, of the gates), and you say you are continuing from Tezra’s answer (which seems to make a similar assumption), I didn’t feel the need to reiterate it. (But you seem to be repeating the fact that portals could be used to sneak troops behind enemy lines.) Also, the last sentence of my comment makes sense only in the context of the defenders controlling multiple cities, including the gates therein. $\endgroup$ Oct 19, 2016 at 0:18

The question is basically "who explores when there is a high likelihood of death?"

In the actual medieval period there were plenty of folks with a much more pragmatic approach to death, so simply good pay could get a number of volunteers to go through the portal, recon the other side (if they survive to get there), and report back. Establishing that pay is sent to the family for those that never report back (and presumably die on the other side) is key. Of course unless there are instructions on the portal about the consequences of connecting to a destroyed or blocked portal, I'm not sure how you would know that failure to return could mean a "dead end" gate address or just an inability to return (they can't "dial back", can't reach the return gate because it opens into a pit, are held prisoner, etc). Anyway, the quality of these pseudo-suicidal folks would probably be fairly low, but so long as their mission is just "get to the other side, turn around and come right back" they should suffice.

A sufficiently powerful king figure could compel soldiers through, but I think he would either have to conceal the fates of prior missions or demonstrate that most (like 70-80%) of gate addresses lead to a safe destination. In the pre-modern era there were travel perils aplenty, from storms to raids to just getting lost in the wilderness. So a certain level of risk was accepted, but few would go into near certain death unless there was a fundamental compulsion to do so (ie a religious "God has commanded this!!" zealous fervor) or some sort of immediate risk for NOT going (the current place is being destroyed/invaded, so without an escape route everyone is dead anyway).

Assuming most portals lead to (immediately) safe places, the usual adventuresome types would gladly explore the other side. Private ventures could fund these missions, contingent on keeping a large share of any profits. The explorers would be gathering exotic animals, plants, and the like, as well as looking for valuable mineral/precious metal deposits. A key member would be a cartographer to map the area and an astronomer (sailor?) to attempt to determine the rough location based on celestial positioning (such as it has been developed in your world). These types of folks are far to precious to risk in the initial portal test however, they would be saved for follow-up explorations.

Another option is to first send through some sort of caged or hobbled animal. This obviously won't verify that the portal is clear, but if you wait an hour or so, then send a human test subject, they could immediately verify if the animal is alive. This would confirm that the air at least is breathable, and probably determine if there are aggressive animals in the immediate vicinity. The key objective is to maximize the ability for a person to get in and get out as quickly as possible but still have the most information as possible, since determining that the gate leads to an open portal is the most critical piece of information.

Opening up a portal directly into a hostile kingdom that could retaliate would be a major concern. Perhaps the return address, if it has to be inputted at the other end, would be entrusted to just one loyal person (the others perhaps given fake address leading to known dead ends) to ensure it won't easily fall into the hands of unknown aggressors. Obviously the low quality initial test subject would have to know it (and his loyalty to the kingdom may be suspect) but that is a known risk and hopefully he will be in and out so quickly that no one could stop him. If the home gate was found in a condition that would have allowed it to be used (ie it wasn't blocked in some fashion) then it would be a reasonable assumption that NO ONE ELSE is currently using the gate system, so none of the gates probably lead directly to an inhabited area.


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