Suppose that radios (or magic with a similar effect) were available during the Medieval or Renaissance era. They're too expensive to give to every soldier or install in every town, but a knight might have a <1-watt backpack-sized radio, a better off noble might have a 10-watt unit pulled by a team of horses, and a large castle might have a 100-watt transmitter. How would this affect warfare and politics?

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    $\begingroup$ Seems like you might be talking about two-way radio communication instead of one-way broadcast...but it's not clear. Note that a <1-watt backpack-sized radio has a range of a couple football pitches, no more. A whistle can (almost) carry that far. "warfare and politics" seems rather broad. $\endgroup$
    – user535733
    Commented May 30, 2021 at 17:42
  • $\begingroup$ With a large entertainment radio, there would be fewer dialects and the differences between them would be smaller. $\endgroup$
    – NomadMaker
    Commented May 30, 2021 at 18:02
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    $\begingroup$ How many radios, how expensive are they, who makes them, what does the society pay for the imported radios etc. (And, about radios. The range of a 1 watt radio depends enormously on the frequency band; from a few kilometers in UHF and such cellular phone bands, to almost worldwide in shortwave, but verying immensely with the specific conditions at the time. Don't try to use such puny emitters in the medium and longwave bands.) $\endgroup$
    – AlexP
    Commented May 30, 2021 at 19:53
  • $\begingroup$ @user535733 1 Watt CAN take you a long way, around the world if you're lucky. People routinely make shortwave contacts over hundreds of kilometers with that kind of power. I'm fairly new on the shortwave bands, and I've talked to South Africa, 10 000 km away, using a portable 10 W station and a wire antenna in a tree. $\endgroup$
    – EdvinW
    Commented Dec 9, 2022 at 12:49
  • $\begingroup$ @user535733 My point is that transmissions are fairly reliable far further than a whistle, like hundreds of kilometers. At least with technology from like the 1920 and forward. There is some variations depending on the season and time of day, but those are predictable. $\endgroup$
    – EdvinW
    Commented Dec 9, 2022 at 15:16

3 Answers 3


Oh the effect would be enormous.


As long as your ship has a radio, you can listen to it and find out when it's noon at a place. Then you figure out what time it is. Lo and behold, you have your longitude. It is difficult to understate how much impact this has on ease of navigation within radio range.


Prior to the telegraph, any criminal can move ahead of news of his crime, because all means of transportation were as slow as he was. Now you can send word ahead and have him arrested. Which leads to another factor.


Power that had to be delegated because the time lag would make it impossible can now be centralized. Burke, discussing the fractious American colonies, pointed out that the distance meant that months were lost in any clarification and necessarily entailed a certain looseness of control. Likewise, ambassadors don't get to make decisions that their governments might dislike once they get the news, because the ambassador can radio back and get instructions.


News from far-off markets arrives instantly. What's more, what could take months of back and forth between merchants in two towns because their letters took a week to travel now can be done in minutes.


Espionage becomes a much bigger problem. Prior to the telegraph, British newspapers freely covered when British troops embarked. With it -- during the Crimean War -- they realized that Russian agents would just telegraph the news. In medieval times, this would have been particularly useful when dealing with Viking raids.

The centralization issue hits again. A general can communicate with his superiors. Still more, an admiral. Much more centralization is possible, though it would have to be developed.

  • $\begingroup$ "all means of transportation as slow as [the criminal] was" - this assumes said criminal can use the fastest means of transport available. A criminal on foot could be outpaced by a messenger on a horse, and a criminal on a horse can still be outpaced by a train with guards/conductors who would recognise a Most Wanted. Wireless is unquestionably more efficient especially for messaging many places at once, but even in its absence a criminal could still have trouble staying ahead of their notoriety. $\endgroup$
    – Xono
    Commented May 31, 2021 at 2:13
  • $\begingroup$ When there are trains, they are as accessible to the criminal as to the police; there were gangs that picked pockets in train stations and immediately took the train and never got caught until the telegraph came along. $\endgroup$
    – Mary
    Commented May 31, 2021 at 2:29
  • $\begingroup$ Also, criminals can have access to horses. $\endgroup$
    – Mary
    Commented May 31, 2021 at 2:30

If radios as you describe them are manufactured in the renaissance, that implies a total revolution in materials science, metallurgy, physics, and manufacturing processes. There would be batteries, wires, transistors or vacuum tubes, speakers ...

This technology should be able to produce electric lights, electric motors (a generator in reverse), and much more. So it isn't really the renaissance as we knew it.

If radios are provided by time travelers, the interesting question will be how those travelers interact with the locals, and what else they change -- intentionally or unintentionally.

Finally there is the magic option, which might be taken halfway in stride if it can be protrayed as "miracles" or "relics."

On the tactical level, probably little difference in medieval times. Armies were not sufficiently articulated to make use of better communications. In the renaissance, there might be some battlefield utility, cutting through the "fog" of battle. But are the armies prepared to issue radios to scouts and not to knights?

On the strategic level, the answer by Mary lists some possibilities. But much would depend on who has the radio and who hasn't got it. Can a merchant go to the municipal radio station and send a message to another town, or is that a privilege for kings? Depends on how many radios there are.

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    $\begingroup$ Armies were not sufficiently articulated because communication was lousy. Give radio to the Romans, and within a year, somebody is going to use it to perform a beyond-visual-range pincer maneuver. $\endgroup$
    – Mark
    Commented May 31, 2021 at 5:05
  • $\begingroup$ @Mark, for the Romans, yes. The OP specified middle ages and renaissance. $\endgroup$
    – o.m.
    Commented May 31, 2021 at 5:13
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    $\begingroup$ Renaissance forces could do it as well, as could the better medieval armies. $\endgroup$
    – Mark
    Commented May 31, 2021 at 7:40
  • $\begingroup$ In early medieval times, it would translate into watchmen looking for Vikings and radioing back the news. Nothing would have a bigger effect on preventing Viking raids. $\endgroup$
    – Mary
    Commented May 31, 2021 at 15:25

Centralization and Bureaucracy

The whole point of having vassals is that the monarch cannot be everywhere in their realm to ensure that their policies and orders are properly carried out.

With (reasonably) cheap, instant communication, those layers of command and control are flattened. The discretion (freedom of action) of each layer is reduced.

The size of the monarch's staff grows enormously, as the volume of transmitted data is far greater than was previously transmitted in letters and dispatches. Courtiers become ministers, with offices and their own staffs (clerks and bureaucrats), plans, metrics, and coordination role.

Subordinate vassals whose data indicates that they are not meeting the monarch's intent can be identified and replaced...unless they are particularly persuasive.

It will be very, very difficult for vassals or courtiers to usurp the monarch or to foment a coup or uprising -- travel to secret meetings and payoffs will be hard to hide from the monarch's radio-equipped Secret Police.


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