Conveniently, their capital got moved to Nifelhold prior to the war declaration , so it's one region away really.
The capital has been in Nifelhold for several months now. Travel times in winter are 12+ hours from Mt. Black to Nifelhold (I have a cavalry unit with vanguard and it takes me as long). Orris is currently in Nifelhold. I don't know what he's doing, but given he hasn't been able to collect a tax yet, nor do I think he holds an estate anyway, he's probably cashing bonds or otherwise getting gold.
Even now that it is spring, it is a 8 hour trip. I haven't seen a court held or a message from Orris in at least three turns. I'm sure that the Devs can check to see what kind of activity he is doing though.