First of all, the Greyhampton massacre was done by Walter for the Patriarch. In Kendals campaine, one of your troops in the tavern says it wasn't caused by the dark legion, and Thomas finds what looks like a part of a patriarchal soldier's armor when he searches the ruins.

Also, I'm guessing that Walter sent Hugh a message that said "his holiness wants some soldiers to attend mass at Jungsburg" so that when they went, they would realize that Greyhampton was destroyed. I guess that Rithrin wanted to be spotted by the soldiers so they would think it was a dark legion attack. He would do that because if Heronadin goes to war with Vellond, it would create enough chaos to allow the Kaedies to come to power, which they did.

So really, Rithrin is responcible for the entire war, I guess. He must have been entrusted by Reignier to gaurd the ancient heart since they seem to know eachother, and Rithrin knew where it was.

Does that sound about right?

does kinda explain at the start of gerals campain, when the village is on fire they accuse the dark legion