I personally despise the idea of duchies warring against duchies in the same realm. It would essentially destroys the last vestiges of team play in BattleMaster. If you want to fight another duchy, then one of you two should secede and proceed to get to fighting.
I beg to differ, and say the opposite would happen. Take a look at Ibladesh: 90+ nobles. Ask the players there about the team spirit, and I bet about 30 characters will just say that they are following orders but don't really feel
involved in a realm, or have no specific individual character line that they are currently pursuing. The realm is huge and so crowded that not everyone
can be involved because that would just turn everything into one very slow and inefficient war machine (or whatnot - I'm thinking of Melhed here). Some people just follow orders and rice prestige & honour, which is always nice later. There are a lot of nobles that actually get a promotion (this would contradict the idea that new nobles don't have a chance in large realms - totally untrue) but even then the "domains" are so split up, also due to the fear of spies, that even a simple region Lord has absolutely no clue about the greater military strategy.
Now, when you chop that realm up into 4 pieces, you will see 3 smaller realms with about 20 nobles and one medium realm (two duchies, e.g.) with 30 nobles. Smaller realms have a tendency to get more "loyal" players, reducing the risk on spies, thus opening up more of the policy for a realm-wide discussion. About twenty players discussing a matter won't necessary flood you with messages each day, and thus it would be possible for more people, to feel more connected. You would have one smaller army (that raises around 10k cs) fighting another duchy, with the same power. You would be more involved in battles and in the decision making progress.
These interducal wars would not lead to the utter destruction of another duchy. The idea to avoid falling back into forming gigantic empires, is having one larger duchy (the "capital" duchy, with 2 cities preferably) having the strongest power, capable of easily squashing another duchy into submission. Combine this eventual military dominance with a mutual religion, your Church can act as the number 1 glue to ensure that no duchies swallow one another. A duke steps out of line and effectively goes against all the policies of the "combined duchies", you auto da fe him and if necessary force some rebellious nobles into submission. Doesn't it work that way, then you have a small civil war on your hands - no problem, most likely the other duchies will team up in a promise of spoils of war.
You see that I am trying to construct some "player-agreement", which would in essence be an out-of-character understanding about some ground rules. It would pretty much be an extension of the current game rules (which are also OOC). I do not have a problem with going
beyond the current game-mechanics to get into an OOC-agreement, as long as it doesn't turn into an OOC-clan. But it shouldn't. Rules shouldn't be bound to a player, but to a concept, making sure that the concept is respected. Besides, if anyone would break such an OOC-rule, it would just end up in what I described in the above paragraph.
However, what I find most important about this is our misinterpreted concept of a "realm" in Battlemaster. Taking a look at the Middle Ages, it doesn't take you a lot of understanding to see that
we have to drop our ideas of nationalism. We, as players, are heavily influenced by several ideological/philosophical concepts of the past two to three centuries. Freedom of speech, emancipation, antisemitism, racism, ... These are a few examples of an endless lists of things that are well settled in our mind (for good reasons), but are completely absent to most of the Middle Ages - there will always be an exception to find, but even then, you cannot name those medieval conditions with an enlightened term. Getting back to the point of this paragraph, nationalism is another idea that simply didn't exist like it does now.
Again taking Ibladesh for example, I too make the mistake of, many times, inciting players "For Ibladesh!" or whatnot (your typical nationalist slogan). In fact, it is wrong. Knights in the Middle Ages didn't fight with their greater realm (let's say France) in mind. They fought for their land, and their liege. That liege might have fought for someone higher up, etc., until you end up with the king being under god. That fighting nobility might feel
some loyalty to his king, but they would mostly act out of sheer selfishness, namely the promised spoils of war or simply gathering prestige. The regular knight would fight in the army of his liege, mostly his count or something of the like.
To summarize: I don't think that the team spirit will be destroyed, but I believe the opposite. Smaller realms will enable more possibilities and create a more coherent group. I'm thinking of Thalmarkin here - they're a wonder, attracting so many players for a one-duchy realm. It would not only reinforce that true bond that is so recognizable in medieval history - the one between the knight and his liege - but also allow a greater role for religion, as it becomes the glue or the "common ground" (also very medieval).
I could go on and on about this subject, and there is much more about it that I have in mind, but until I get a chance of actually implementing this idea for real, I am still constantly evolving the concept and deepening out the historical aspect more and more.
Having said that, the loss of the message channel to be able to talk to each other is definitely a hindrance in what you're trying to do. Then again, if you're fighting each other, that common message channel will just be filled with so much crap, it will be intolerable. We had that happen in SA. Trust me, *not* having free access for both sides of a war to send each other messages at will is a rather large boon.
I'm not aware of what specific construction SA had, but I believe that these guilds should only be used in cooperation. In essence, when your "realm" fights another realm or goes on some form of crusade, you use these guilds to coordinate properly with eachother. When the duchies start fighting eachother... well, then it's time for either applying some established OOC-rules that will avoid this of happening, or a powerful figure to put an end to it (temporarily remove/disable/diffuse the situation). I think there are many ways to go around this. The idea here is not to have ALL nobles united in one guild. That should already have happened in the religion, for one, and defeats the concept of creating these smaller duchies with a more coherent group of players. Duchy first, then the "greater" realm. That summarizes the concept, really.
