Westmoor an ally? Please. 
And the reason all those realms went to war with Sirion is because they wanted to fight in a war. Not because of some(most likely fabricated) excuse that Sirion was selling them out.
Sirion is neck and neck with Perdan population and food wise, produces the most gold, has the most nobles, is the most defensible, and probably has the largest mobile army and your telling me they AREN'T the strongest?
And just about any realm would have major defensive problems if a whole duchy seceded from their nation. But I suppose all realms die eventually. Fontan was the top dog at one point too.
"All those realms" were already fighting Fontan along side Sirion and OR. Why, pray tell, would they "want a fight" when they were already in a war? Especially when gaining lands would have been easier/more feasible when warring Fontan?
Is it possible the evidence was fabricated? Yep. Is it likely? Well, from what I've heard, Sirion wasn't doing too hot at that point in the war. Need to bug Merewyn about that time period again.
