What does "Unfortunately, it's too late for that" mean when I tru to advance to Geinvrik?
you waited too long until after their rebellion started and the 5th legion's siege succeeded and they took Osta
there should be an event of a soldier coming into your tent to tell you that Osta has fallen and it's too late to get Geinvrik
obligatory it was actually 7300 vs a host of minimally about 200000 Persians with some estimates nearing 300000 (I happened upon this while desperately checking to see if anyone had answered my question in these comments)
I don't entirely get what you're saying, I know about the event and the historical draw for the characters
Just go to Geinvrik before Kemeq and you'll be fine.
