Disposition of forces to send:
1st and 3rd Company, with their respective Captains. Over-all command goes to the Chapter Master, who will be personally attending.
Take Silence of Death battle-barge and Ravendare Strike Cruiser, as well as assorted lesser craft.
Azakniel comes with recruits, as well as our Librarium.
We have two Predators and a Land Raider, right? Bring them with our Master of the Forge.
I'm advocating full on war. Not just because of the Mantis Warriors, but because Tyranids are serious fucking business. We'll leave one company with a Captain I think would be best capable of leading on his own behind, just in case, but mostly, the Chapter goes to war.
I also suggest we speak with the Sororitas before heading out, if they're still here. Let them know who our representative is, the remaining Captain, and let them know why we are heading out in such force and haste.
Hopefully they'll decide to tag along, but we won't ask them for it.