# How fast will information travel through my chain of command?

In the story I'm writing, there is a lot of medieval warfare. I want to know how well information and commands would be able to travel through my armies (clarification: by how well, I mean stuff like the length of time for an order from a leader to get to the rest of the army and the length of time for information from scouts to get back to the leader; I don't need to know if the orders will get distorted).

Organization: I couldn't find much good information on how typical medieval armies would be structured, so I made my own. Lowest on the totem pole are the foot soldiers, archers, and cavalry. Captains are ranked above them, and they carry out order for 10 to 20 standard soldiers. Then, centurions give orders to about 10 captains or 100 to 200 soldiers. Then, commanders control about 1,000 soldiers or 5 to 10 centurions. The generals command the rest of an army regimen which would usually be about 5,000 soldiers, but in my story the biggest battle includes an army of 25,000, so let's say that that's the number of soldiers in the army.

Communication: The general usually sends a message down the chain of command, giving a message to the commanders who give it to the centurions who give it to the captains who give it to the soldiers. If a soldier needs to carry a message, then vice versa is done. When preparing for battle, the army uses a horn system. The first group to see an enemy will send out a horn call which will be mimicked by every other group until everyone in the army has heard of the attack (a group is a captain and his men).

Scouts: When traveling, the army sends scouts ahead. Groups of scouts number about ten, and to send a message, the scouts send two people back to the army. If the army wants to send a message to the scouts, two soldiers will ride to them. Scout messages are given directly to the general.

With all that information, don't overthink this question. I'm only trying to ask one thing: how easily will information travel in terms of time? The use of this in the story is for me to accurately depict how fast a new order from a general will travel to the soldiers.

Edit: Just to put what I said in the comments into the question, this is a battle scenario in a set-piece battle. This question is for the scenario of a new change or order occurring in the middle of a battle.

• How fast would an order or a signal travel in what context? Is the army arrayed for a set piece battle? On the march, and in how many columns how many miles apart? On the march through open country or through rough country? Dispersed as to reduce a number of castles about half a day from each other? Busy occupying the whole of England? Commented Jun 18, 2023 at 20:11
• @Cadence While the message travels as fast as the carrier, I want to know if the way I move information will increase of decrease that base time. If there is a change in battle tactics during the middle of a battle, how fast until it can start being implemented? I might edit the question to make that clearer along with the complaint from AlexP and any other comments that show up before then Commented Jun 18, 2023 at 21:01
• You might consider reading some of Bernard Cornwell's medieval themed military historical fiction. Characters tend towards the anachronistic, and there's some mild pro-English and anti-Catholic chauvinism getting in the way of overall historicity, but the ground level view of military history is as reliable as anyone could ask for.
– g s
Commented Jun 18, 2023 at 21:32
• I try not to close the questions of new users, but this is far too story-based. Simple info or complex? Drums, trumpets, smoke signals, or semaphores? Runners, horses, or ships? Is it raining? snowing? night? day? Is the terrain flat? hilly? mountainous? bogged? What's the health of the runner/horse or the condition of the equipment? How fast can the info be interpreted and acted upon? All these and a LOT more is dependet on your story. Even averages are story-based. Too often this information depends on narrative necessity.
– JBH
Commented Jun 18, 2023 at 23:30
• That kind of organisation isn't very medieval, it looks more akin to the well organised armies of Rome or of later periods. In the medieval period, because armies were constructed from complex chains of feudal obligation and raised for only short periods, they did not (could not) have such neat hierarchical structures. Commented Jun 19, 2023 at 12:13

It depends

First, forget about the captains in the context of big army set-piece battles. Other than specialist scouts, miners or engineers, a unit the size of a modern squad or section is not going to be operating independently, they will only move and fight as part of a larger group. Which means that the real question is how long it will take for orders to get from a general to a centurion, probably via a commander.

Second, forget about giving meaningful orders to a unit that has already engaged the enemy in melee. Once a soldier is hacking and slashing, blocking and parrying against the enemies in front of him, with all the accompanying battlecries, shouting and screaming of the wounded and dying, there is no way that he is going to pay much attention to anything other than his piece of the battle. You can shout orders and blow trumpets and whatever you like, he's not going to care. The only thing he will notice is if the people on one or both sides of him start going down and not being replaced (or running), at which point he is likely to follow suit rather than dying in place.

Which means that the units that can be meaningfully given orders are those that are not yet engaged or are ranged units. In turn, these orders can be divided into those that were part of the battle plan and unplanned responses to a changing situation.

A planned order can be given very quickly, especially if flags are employed. If the commander on the left flank has been told "Advance and secure the bridge when a green flag is waved three times" then he'll have a couple of eagle-eyed subordinates watching the army command group for that flag and he will have tasked each of his centurions so they know exactly what they are to do when he in turn waves a flag or blows a trumpet or whatever. Elapsed time from the general telling someone to wave a green flag three times to the centurions shouting "Advance!" could be less than a minute, assuming line of sight exists. Or the commander may not be looking for a flag, he may be following contingency orders regarding when to conduct action X, for example, "once element Y reaches location Z, execute action X". See the final paragraph for why this is more likely than looking for flags.

An unplanned order is a different story. A runner would need to be sent to tell the commander on the flank that things have gone pear-shaped and he needs to send a couple of centurions with their troops over to the other side, or whatever. (Contrary to another answer, medieval archery did not have the accuracy or range to be a significant threat to a runner moving to the rear of units that had not engaged.) The possible variations in terms of who has to go where and do what are so great that it is infeasible to have pre-arranged flag signals for all of them. Which means that it will take time for the runner to reach the commander, then the commander will need to either summon or send runners to his centurions for a quick orders group (O group). Depending on the complexity of the orders, the centurions will each then either return to their troops and shout "Follow me!" or they will need to call their captains in for a quick O group. The exact time before soldiers start moving in response to the general's new requirement could vary from minutes to an hour or more, depending on the distances involved and the dispersion of the troops. (If you want to know how long it would take in a particular situation, roleplay and time the conversation that would occur at each level and add the necessary transit times for the runners and commanders.)

A few more things to note. First, medieval armies were small compared to both ancient armies and those of the Renaissance period. 25,000 soldiers is an enormous army for that period. (The French may have had 25,000 at Agincourt, if armed servants are counted.)

Second, armies were organised along feudal lines - Lord X would be told to bring along a number of troops and he would pass the requirement down to Baron Y who would in turn tell Sir Z. These troops would be made up of the nobles, a few trained retainers and mostly a bunch of peasants taking time out from farming for the summer. Each noble would command their subordinates and the overall level of training was very low. The lack of training matters here not because of fighting ability - the conscripted peasants on the other side were just as bad at fighting - but because they could not execute complicated orders well. Do not try to portray medieval soldiers as Roman legionaries or Greek phalanxes or Renaissance professional soldiers moving in neat squares as ordered, because this was amateur night in comparison.

Third, another consequence of the feudal organisation and amateur nature of this army is that there were generally (no pun intended) no "quarterback generals" - an army would be led by a noble who was expected to lead from somewhere near the front. Which means that the leader (albeit wearing much better armour than almost any of the other combatants) would be distracted by people trying to poke him with pointy things and would not be giving many orders at all after things kick off - subordinate commanders would be acting on their own initiative and/or contingency instructions.

• Out of curiosity, how did you know about the usual army sizes in medieval vs. ancient times or [1 or more of the 3] renaissance periods? Commented Jun 19, 2023 at 14:00
• @Sixtyfive I may be the question poster rather than the answer poster, but this link has helped me in the past with medieval era armies. Commented Jun 19, 2023 at 14:40
• I would not include Greek phalanxes in among well trained units. Macedonian phalanxes under Alexander maybe had some experience, but for most of Greek history they were citizen armies and had no training either. All they could do is form up facing the enemy and advance. Commented Jun 19, 2023 at 18:49
• @fectin, yes.
– Mark
Commented Jun 19, 2023 at 23:25
• @Sixtyfive partially from watching Lindybeige videos on YouTube, especially those looking at the scale of siege engineering in various periods, partially from research for an answer on SciFiSE scifi.stackexchange.com/questions/254927/… The blog A Collection of Unmitigated Pedatry also provided useful information and triggered some research. Commented Jun 20, 2023 at 11:40

In addition to the answer by KerrAvon2055, let me point out that that historical medieval chains of command would be tied to feudal chains of allegiance and honor. A competent commoner could not possibly give orders to an incompetent noble, and even a king would have to be careful how orders are put to the dukes. That puts a significant demand on the time of the leader, and on the polite transmission of orders.

Another thing to keep in mind is the near-total lack of staffs. In a modern army, a small patrol would report to their platoon leader, that platoon leader would report to the battalion intelligence officer, who then consolidates reports and passes them to the brigade or division intelligence staff. The brigade intelligence officer would be sending information requests and expect briefings. For more urgent events, the information would be passed through commanders who are on connecting radio nets. The scout platoon leader is on the battalion net along with the battalion commander, the battalion commander is on the brigade net along with the brigade commander, so the report would be passed through a few senior people.

How fast medieval scout reports will reach the top general will depend on who the scouts are and if they are expected. Unlike the modern example above, the scouts would need an audience with the general and that is not normally granted to random foot soldiers. So either servants, bodyguards and aides of the general expect those scouts to report, and pass them through quickly, or the scouts might spend lots of time in front of the tent while the general speaks with other people. A king could not leave a duke waiting while he talks to commoners, the duke has precedence. Even a senile and long-winded duke.

Given your comment was for context in Battle - The answer would be approximately 'The speed of sound'

Why?

Well - because the General would be unlikely to send runners during a set piece battle.

A Single stray arrow could stop a message - this is why historically, Drums/Pipes/Music was used to signify major events, such as:

Assembly (777 flam flam 777 flam flam 777 flam flam 77 flam flam 7);
Drummer's Call (7 flam flam 7 flam flam 7 flam flam 2x fast, 1x slow, 7 flam 7 flam);
Simple Cadence (Open Beating) (5 5 5 flam flam, repeat);
this is played to the rhythm "left, left, left, right, left; the 5's are the lefts and flam flam is for right left)
Reveille (it's 7 songs long, but usually only Three Camps is played);
To the Colours, which signals the men to Rally or Form by Battalion and is used as a salute to the flag.
Three Cheers- used as a fancy roll of during ceremonies like Retreat, Tattoo, and Dress Parade.
Long Roll- used as an alarm (immediate assembly under arms) and cease fire.


For civil war re-enactment

The General would have their detachment of signallers/drummers/pipers/flag wavers - who would then issue the command so that it could be heard.

In terms of time from issue to reaction could be a few minutes depending on the situation.

However, that is for a major battle.

For day-to-day admin of a large Military force through a country, this could be several days for orders to get from headquarters out to a garrison and then actioned.