Got it. Well, it's nice that they confirmed Glenn is named after Frog. It makes me wonder who General Viper was working for. "Glory brought on by Porre" still makes me think the Acacia Dragoons were a colonist offshoot of Porre, but if Viper was fighting on the continent during his own lifetime, well...the preeminent conflict back then would've been the invasion of Guardia, right? Just hard to know...
They are. It was Porrean colonists who arrived at El Nido in 920AD, the Viper Clan among them. And the war they fought was indeed the Fall of Guardia. Despite FATE not allowing El Nido natives to leave, because of the Dragoons' role in the Fall, it allowed an exception, since it was to preserve history. Since in the timeline without El Nido, the Dragoons remained in the mainland, as shown in Radical Dreamers.
Basically, relations with Porre were fine... so long Porre left them alone. But when Porre had signs of meddling, or even taking over, relations naturally soured.
At least, that's my interpretation of the whole thing.