I was playing a game with 2 opponents. One of them declared war on me, so I trained a couple of units equipped with spears and went and killed the enemy sovereign. That ended the game as a victory for me. I had not defeated the other opponent, so either there's a bug or the other sovereign was killed by a troll or something.
Anyway, I'd like to suggest that when an opponent, even one you haven't met yet, is killed, that you get notified.
In case you need it, here's the debug.err.
