Just because they may have been planning this for years, and for reasons independent of the war, doesn't mean that the timing wasn't influenced by the strategic implications. I doubt the timing was totally random, and while there were likely other factors involved, it's hard to believe that the strategic implications in the current state of war didn't enter into anyone's thinking. If they really didn't wish to gain a strategic advantage in this war then let them sit this one out, or at least stay out of it for a specified period of time. That way the opposing realm will have time adjust its deployments accordingly. Otherwise it's a veiled strategic secession and it puts the opposing realm at a disadvantage.
