In this latest adventure the party's squad has split up into four squads of 6, the pcs' and three squads of npcs.

90% of these npcs are named people with faces and personalities, so arbitrarily deciding who lives and dies isn't really a satisfying option, but aside from drawing up stats for all of them and running through each encounter I'm having a difficult time coming up with a good mechanic for determining how well they do.

The threat to the squads is rather significant and I would expect at least one person from each to die unless they are particularly lucky. (I'm expecting the pcs to have a hard go of it in their encounter, so the npcs should deffinitely have no easy time)

So, does anyone have any suggestions on how to deal with this in a creative and effective manner?

Whoever means most to the players. Whoever they like the most, or whoever has the potential to be most helpful to them in the future.

Of course, they don't have to die, they could just be horribly maimed and wounded. This would mean that the PCs will need to spend time and resources trying to help them, or bring them to safety. Or make the dreadful decision to sacrifice them, and leave them behind....

Assign each NPC a number. Roll a die. That one's dead. It's arbitrary and completely disconnected from how the PCs feel about them, which is how death should be. Hopefully it'll be a sobering moment for your players.

I'd play it depending on the PC leading the group. If he/she gives good commands, is careful, and does well in combat personally, those actions help save the squad. If however the PCs is lacking in either leadership or combat skills, that means 1 or more of the squads dies or heavily injured.

I agree with Friend of the Dork. Allowing the PCs some chance to save their buddies (or cause them to die) is a more involving for the players than reading out the butchers bill at the end of the mission.

Besides command test and combat performance, throw some Navigation skill tests in, have some vehicles that could be utilised, tech that needs to be activated to get them somewhere, etc. Use the whole range of skills avaialble to stimulate battlefield obstacles.

When they fail these tests they merely take longer to acomplish the task, when they succeed they go faster with the degrees of success dictating how much time is lost or gained. Possibly have a death clock where you work out when each of the npcs die and in what manner. If your players manage to reach them before that point in the clock they have saved the npc, otherwise they were too slow and hear them dying over comms.

Good idea, but perhaps I didn't make it clear enough that the npcs in question are in their own units, not lead by the pcs in this mission and thus the pcs have no direct control over whether they live or die. Basically they are splitting into four groups (the pcs making up one) all hitting sepparate locations at more or less the same time. If the pcs weren't getting emotionally attached to their "Blackbirds" it wouldn't be an issue, but they are a military unit (think a small version of Gaunts Ghosts) and so it will be important to know how many and who dies at the end of the fight.

I have been thinking of assigning each of the pcs one squad for whom they are responsible karmically ... when the pc takes a crit in battle, one of the npcs (determined randomly from their squad) takes a crit of a randomly determined severity. So, if the pcs get pasted too bad, so do the npcs - though the npcs have the mercy of dividing the punishment of once pc between all of them.

I'd do it like this:

Assign each NPC squad a general Mission Competency characteristic (based on who's in it, what capabilities they have [combat, command, stealth, etc.] what they're assigned to do, etc). Then assign a similar characteristic for the comparative difficulty of the opposition each squad must face. Roll an opposed test for each squad vs. target - for each degree of sucess the squad wins by, they achieve a portion of their objective (beat one encounter, whatever); for each DoS they lose by they take a random casualty (maimed or dead your choice). Continue as an extended test until either all objectives for that squad's mission are met or 100% casualties.

That way you take care of each NPC squad's mission in a single extended test, and since the numbers you assigned were based on comparative ability its not completely random nor are you just dictating "this guy dies, that guy lives" etc.

Also just a random thought. Of the forum suggested NPC's in the earlier thread re this plotline, which ones did you use? And which ones do your players like best?

Alternatively, think about them from the point of dramaturgy. Whose "character arc" is already closed, who would serve a more important dramatic function in death than in life and who would still provide you with a lot more story material if he was to live through this?

I'd try and work out which of the NPCs is a favourite with your players, and look at killing him off in a blaze of glory - make him a hero, who took a bullet for another guy or died against dramatic odds, and your players will remember him as someone to look up to. Remember war is hell...

I had one of my recon NPCs (Fishbiscuits) go down this way - the players could then see the impact his death had on his NPC mates, and get the idea that this is a dangerous business.

In my games one or two major NPCs have popped their clogs. They still fondly remember assaulting a crash-landed Chaos Reaver ship led by Brother Tregard of the Space Wolves, who promptly took an axe to the neck and survived before going down by bearhugging an escaped daemon-host long enough to allow the rest of them to escape.

If you get your players to talk about NPC exploits outside of game-time, you've cracked it.

Probably not the most conventional way to deal with this sort of thing, but being as this is Dark Heresy and directly related to Warhammer 40K I think this might be rather fun for your group. Included in the big battlegame are also rules for quick lethal dustoffs that can be played in under and hour, give or take called "Killteams"

Basically you put together a small (hopefully lethal) strikeforce to make some brave special-forces style attack on some important foe that just needs killing, a calculus logi that needs to be destroyed, a secret bunker that must be set to blow from the inside or something equally brave and cool. The idea was that players would take turns playing the heroic aggressors with elements of their own much bigger army and then trade off and play the at first clueless defenders. Think "the Dirty Dozen" or "Schaffer's Last Chancers", but with Imperial Guard commandos sneaking into a rebel bunker to kill the traitor Colonel scheming inside of his supposedly safe lair. or something like that. The big excitement for tabletop players is because the Kill Team is kitted out especially for some stupidly dangerous speciffic mission they get to break some of the rigid force composition rules from normal units. "So it is a Catachan Devil squad, but there are only 8 of them, two sergeants, a sniper, a medic and some crazy old greyhair with a demo pack as big around as a tree stump? Cool. What's the mission?"

It would seem simple enough if you have mineature players in your group to run the acolytes' team as normal in DH, then let each player pick his favourite team of comerades that they wish to control, have them put together a suitable mineature representation of the team, then allow them to one by one play out the side missions on the tabletop. Lots of drama and excitement, plus you will know exactly how things turned out. "Poor old Sergeant Thorsson, took a gut full of shuriken from those unholy Eldar guns, but tough old bastard that he is, he took three of them screaming off the bridge as he fell. He will be missed."