Hello Fellow GMs. I come in search of advice.

My PCs are on an endeavour involving hunting down the remnants of the Meritech clans in alliance with a pair of other rogue trades, an Imperial Navy battleship group (battleship, pair of cruisers and 6 escorts) and an Admech battleship group (same as the Imp Navy group).

They've been very clever in arranging al this and tonight is the big showdown, they are ambushing a meritech support fleet to draw in 3 splinter fleets so that they can be utterly annihilated.

But how should i run it? I've already decided that the battle will effectively be broken down into three groups as the Admech, Navy and Rogue trader fleets each tackle a splinter fleet.

While the rogue trader fleet gets stuck in (i use a board and BFG minis for space combat) how should i keep in my players minds their connection to the greater battles raging across the solar system? How should i run the whole shindig?

I toyed with using BFG to run it, i have everything i need for this except sufficient minis, but my players aren't wargamers and probably wouldn't enjoy it.

Has anyone else run a large fleet battle and if so how did they handle it?

To give you some idea of scale, my players dynasty bought 6 ships (cruiser, light cruiser and 4 escorts) and their allied rogue traders (Hadarak Fel and Solomon Haarlock (in my campaign a fairly decent chap trying to redeem his dynasty's legacy) have each bought a cruiser and a few escorts).

First decide how many other ships you want the players to fight, obviously they are not going to fight each and every opposing ship.
These will be the enemies they will face without support of the Admech or Navy ships.

Second build in several events where they can either call in or give support to other ships forfeiting their turn, not helping another Navy or Admech ship could have some disadvantage in the future

Third, describe what is going on around them, what their sensors display and how the fight is faring.

You could try to roll for all the individual ships but that on your own time, or rather, don't.
Determine the outcome most beneficial to your story and have the pc's duke out their small part.

I think you have to decide on where you want to be on the sliding scale between solving it narratively and as a full boardgame (BFG style). Not being wargamers, you should be closer to the a narrative solution (but not quite).

I think we all agree that It's imprortant that the players have ownership of the outcome of the battle, i.e. the battle is theirs to lose or win.

Option 1: A series of small problems presented to the players that plays to their speciality roles (Astropath = must relay vital fleet information for other fleets, due to difficulties getting a signal otherwise, Voidmaster = void strategy, Navigator = The meritechs have a Yu'vath device that creates localised warp rifts (a bit like ship mines) must use Eye to see and avoid, Militant = boarding action?, Missionary = Attacked by Xeno device? that tries to mindcontrol the ship via vox. Must recite prayers and hymns to cancel the effect. The Emperor protects. etc.... Degree of successes count toward the result (Standard stuff)

Option 2: The players finish "their" engagement, but something is wrong with one of the other engagements. The meritechs are using an unknown weapon (Yu'vath again?) that seems to disable ships and cannot be hit in realspace. The players must rush to the rescue and engage the ship inside the warp (with all the fun that means =)

Or why not both? (though it might take a few extra sessions...)

I allways go the narrative route myself, as the wargame route is too timeconsuming usually.

BFK have rules to simplify space combat for non important NPC ships. I have not tried them, but maybe they will be workable for you?

Have certain predetermined keypoints were an interaction with the other parts is neccessary. For example:

The MeriTech Units do not exactly group as estimated, the Navy-Detachment is confronted by way less enemy vessels than anticipated, a part of the Enemy's Fleet seems to be missing.

Combat Round X: The AdMech Flotilla is in dire straits as it is attacked by a second unanticipated MeriTech-battlegroup.

The Players can:

a) send reinforcements from their own squads: This buys the AdMech-Units Time before the battle becomes critical again (at which point the Players should have won their part of the battle and come to the rescue, or the AdMech will be beaten; see option b) with a little less MeriTech vessels joining the fight), the more and better help they send, the more time it buys. If they send really much, the AdMech will win their part of the battle.

b) do nothing: So the AdMech will be outnumbered and beaten in a set number of turns, at which the surviving ships of that MeriTech-Wing will join the battle with the Players.

c) request, that the Navy-Detachement sends help: This buys the AdMech a little Time but lengthens the timespan the Navy-Units need to win their battle.

Combat Round Y (or later see Option c) in Combat Round X): The Navy-Commander has broken the MeriTech-Squads he was facing and has at last realized, that the remaining MeriTech-Ships are just trying to keep him busy while the AdMechs get hammered. At this Point all of his ships that are still battle-ready join the main-battle as well as some surviving MeriTech-Escorts.

That way (or similar) you'll have tactical decisions for your players that take the battle as a whole in fokus and you have some turning points for your players. How good or bad these turning points are depends on the perfomance of your players. If they did well and decimated the enemy fleet with little losses of their own befor Round X, they can send heavy reinforcements or even gauge that they can win, their engagement before the AdMechs are completely beaten.