Random Declaration of Wars?

I'm minding my own business, going for a peaceful victory. End my turn, and at the beginning of my next it says "You have declared war on Boudicia" despite the fact I've not entered any event or conversation that means I should have done that.

I can't tell if it's a bug or something that happens due to a knock-on event.

Anyone seen this?

Have you signed a defensive pact with anyone? If so, Boudicca might have attacked the leader you signed a defensive pact with and so the game automatically declared war for you.

Ahhh! Is that it! I have signed a Defensive Pact with lots of people.

Thanks so much!

Oh well. I wish it had alerted me and not said I'm a jerk for declaring work after our own Decleration of Friendship.

If pursuing a peaceful victory, avoid making Defensive Pact with anyone.. Seems like a lot of leaders are suddenly trigger-happy once they got into Industrial age.