I had an odd thing happen today while playing a game. I had my sovereign and a few archers in one of my cities, playing guardians while I waited for more troops to be build. I noticed one of Gilden's champions (who is at war with me) casually stroll past my city all by herself. So, I selected my sovereign (and the archers) and attacked the enemy champion. After the battle, which I had won, my entire stack of archers and the sovereign disappeared. I noticed that I still had the "center on army" button for the sovereign, so I clicked it. It took me halfway across the world, to my sovereign, who was now all alone outside one of Gilden's cities. I also noticed that I had a "new" "center on city" button as well. I clicked it and found all the archers that had disappeared. Seems taking out that one champion netted me a city as well.  I have no idea how one would go about replicating that. Funny thing though, Gilden wanted peace 2 turns later. And he hasn't attacked me since. He's probably worried that I'd end up magically occupying all of his cities if he did.