I have a question here (or several questions). Will you be able to, for example, join the milatary of a town/civilisation and be part of their army as they invade places? Because that seems badass. Also, will civs fight for "land" (army vs. army in open battle) or will battles only take place in city's (attack/defend)?
Another question, how will this "scared" thing work with archers? If its based of skill level and armour, then archers will just be overwelmed with sieges and run for the hills when they see them rather then shooting from the battlements. How do you plan on fixing this? Also, what attribute will be tied with bravery in battle?
Edit; Oh, and another thing. How will we be able to tell who is on our side and who isnt if 2 of the same races are at war? Will there be some kind of marking that members of a civ wear, or a different color, or it could just be in their name. Also, on the subject of armour, could you kill a member of a civ then wear their armour as a discuise and infiltrate into the other civ?
I'll take a license to answer some of these questions, at least what I think about them; maybe I could be corrected by someone more knowledgeable than me.
The army joining stuff is certainly planned, but I don't think it will happen on this release (as Toady has stated a few times from now, that would be overreaching). A few devlogs ago, Toady told us that with site claiming there would be small groups pursuing basic goals, and that you could be more free than before to be on either site of the equation, now that allegiances are getting pretty diverse. "Land" fighting, as far as I know, was pretty scarce even in medieval times; sure, media shows us the impressive charges of cavarly on the open battlefield and it fills our lungs with awe, but things were rarely like that. When huge armies stop being too abstract and their paths collide, that could ensue a match of forces, or even in a arbitrary place if it entails some relevance for any of the involved entities. Again, something for a future release.
I don't think being scared or not relates to an attribute, more than it does to personality (which already has a decent framework) and maybe to survival chances, represented on being well armored. Fleeing from combat, as I've read, will be related more often with escalating levels of violence and the threat of death, but someone asked Toady if the Fortress Mode would present something related. Surprising stuff it was to know that even armed soldiers could flee from combat, as that tends to happen every now and then in real life. So your battlements won't be empty at the arrival of peril, after all we're dealing with dwarves.
Right know, you already know who's your enemy and who's your friend given the decent knowledge you have about the latter, before entering combat. When you look around and peek over your companions, their names and status are already granted, while the hostile forces are only known by what they're supposed to be or which kind of deadly tool are they carrying around. On a larger and more colourful battlefield, surely you're not supposed to know the name of each and every allied soldier that fights for a vaguely similar cause than yours, an hectic mess is to be expected with all the blood, limbs and ‼dwarves‼ running around; but without a doubt, Toady has something planned for the UI to help us, without conceding something too gamey that wash out the inherent fun of such a situation. As with the former questions, we'll know when he gets there.
The new stealth mechanics look pretty great, and it has been already stated that disguises and other means of subterfuge are to be expected to flesh out the art of being incognito.
Here's what I found out at the Development page (that still needs to be updated, you'll notice that some of these have been accomplished)
Breaking into fortified locations
Having locations alerted, being able to yell for help
Disguises and impersonation through use of entity uniforms
Closed doors and passwords
Sneaking mechanics
Making hiding impossible in wide open areas (at least in adv mode)
Vision arcs for patrolling guards
Gagging people and tying them up
Allowing constructions to burn, use of kindling/hay/etc. where reasonable
Responding properly to personal fire issues (all modes)
Fleeing burning buildings
Fighting fire (all modes)
Designation to set item or tile on fire in dwarf mode
Sorry for the long answer. If it wasn't me, maybe someone else would have gladly helped.