historical versus mythic

No, what it later says is quoted below

No mention of a size limit again,and while that's not necessarily the main thing, it does suggest that a group of 7 could be an untrained group, in violation of the earlier limit, in the instance where there are 7 grogs, and the leader only has a score of 6.

Not sure why there is a limit of 6, and what that actually achieves...

No no no! By definition, at the very beginning of the "Groups" section, a "group" in Arm5 combat may only consist of 6 combatants or less. Anything with 7 combatants simply is not a group. Nothing written in the rest of the section applies to it. Stop reading and move on.

It's a bit as if I said: "A village may consist of 1 to 30 buildings, inclusive... If the village has 10 buildings or less, it's a small village. If it has more than 10 buildings, it's a large village". The last sentence does not suggest that a (large) village can have more than 30 buildings. Because beyond 30 buildings, it's no longer a village. Similarly, when the corebook says "The maximum number of fighters in the group is equal to the leader’s Leadership score" it's saying "The maximum number of fighters in the half-a-dozen-fighters-or-smaller team that these rules call a group is equal to the leader's Leadership score".

Alas, if I haven't convinced you so far, no argument of mine will. It just seems so obvious to me (and anyone else I ever played with) that I never even thought someone could read it your way.

I think that the idea is to keep in check the trained group bonus (which can already get really really large as it is). It also achieves the fact that once you "mastered" your Leadership skill (i.e. have a score of 6+), you can coordinate any group effectively (gaining the bonus if the group has trained together). Again, I say "any group" because if it has more than 6 combatants it's not a (group combat rules) group by definition, full stop. It's not even an untrained group: e.g. you can't designate a vanguard and use his combat statistics "for everyone else". If you have more than 6 combatants, you have to break them up into sets of 6 combatants or less, or use combat rules for individuals (which is equivalent to using group combat with groups of size 1).

Oh, I'm well ware of how it reads now, with the hard limit to group sizes being 6.
I just think its important enough to repeat a couple of times in the section, especially at the point wher it says the maximum size is the Leadership score. A simple leadership score or 6, whichever is lower.

As to the bonuses, yeah, I see it. Of course just match them up to other smal groups. I generally run a group of 4 in one saga. It is pretty lethal.

So no football in mythic Europe, the teams are too big to exist (besides you can't have American football before discovering America)

It also occurs to me that Alexander the great could probably be better made using seasonal advancement rules from childhood, given that he was reputed to have had some of the best teachers available at the time. If a geezer with a leadership of 16 (could write a book of level 8 ) and a SQ as a teacher of about 15 per season +6 for one on one instruction was the last to teach him leadership at age 14, then the normal limits wouldn't apply to Alexander...

Well, you are comparing Alexander's ability to lead an army to that of small squad, Trained Group rules, and under Ars, they are quite different.

I have a problem with the hard limit of 6 as being arbitrary, and having no reason behind it. The fact that it isn't mentioned as a limit to the leadership is also odd. Something as important as an upper boundary is important to mention when certain skill like Leadership can easily exceed said boundary.

Leadership is also handy for calculating the number of helpers in the Lab, without any limit.

Of course, there are many uses for the ability, that's not the issue I have (or even mentioned).

I would point out that the limit applies even when Leadership does not come into play, i.e. when using untrained groups.

It's just that group-combat rules are designed to model small groups, and "break" in a number of ways if groups start getting too large. Let me reiterate that this does not apply solely to trained groups. So I don't think it's arbitrary to set some limit to how large a group can be under the group-combat-rules model.

You might say setting the limit exactly to 6 is arbitrary -- it's not as if things would be radically different with a limit of 7. But at some point you have to draw the line, and 6 does not look a bad point to draw it, at least to me. It has the advantage, as I stated, that it's the point at which a Leadership score of 6 ("professional mastery" according to the rules) is sufficient to lead effectively any trained group.

I've thought about it a bit, and 6 is fine, but IMO, it's a fairly big oversight not to mention it again when saying trained groups size limit is the leadership score.

I was forgetting the role Leadership plays in determining the combat bonus. Higher leadership is still really important in delivering combat bonuses, say a group of 6, with combat abilities of 6 each: that's 5x6=30 to the attack roll (not counting vanguard). A bare professional (Leadership of 6) can only utilize 3x6=18 of that bonus to the vanguard, while the 7+2 leader in the OP can utilize nearly all of the available bonus at 3*9=27.

Lords of Men might be more relevant here anyway. Page 133 is relevant for uses for leadership by a grog captain etc.

For much grander scale combat, of the scale you're talking, you want to look around page 105 of Lords of Men.

Why ever would he try to give orders to each individual personally?

400 under a single persons command is perfectly viable, realistic and even normal, even if on the large side.
The leader would give a command and then someone with a instrument or a flag would signal, and the whole unit would respond. Depending on era and place, sometimes it would be subcommanders that executed the orders subunit by subunit, but elsewhere and when, all within a unit would have to keep their eyes or ears open.

Both have advantage and disadvantage. A unit commanded through subunits is always slower to respond, while a unit commanded as a whole is always at greater risk of falling into disarray because it“s easy to miss a command.

Having 4000 under personal command of one would be difficult, but definitely not impossible.

The classic US cavalry of the 19th century is a perfect example, where one instrument could instantly signal to a whole unit, with a size of 500-1000+ soldiers. Of course they still had subunits, but the point is that they could ALL respond to a single command from a single source.

Japan also played around somewhat with large singlecommand units, using visual or audible commands, sometimes including fireworks, with units up to as much as 800, though rarely larger than 400.
China on the other hand, like Rome, stuck to a very neat chain of command system.

While the Mongols were another people capable of using large units effectively under one commander, sometimes very large. I think they may be the ones ever coming closest to the earlier figure of 4000(about half that size IIRC though).

There would still be someone at a level below Alexander ensuring that the grunts were executing the orders that were given.