It's always fun for revenge stories too!

I had one game in I think Civ V where Dido was just being an asshole to me the entire game, and in the sort of mid-late game she did her big move and invaded. I lost maybe 3 cities, then the defenses started to hold and I pushed back. Took my cities back and then just kept going, and absolutely refused all offers on peace (which were becoming increasingly elaborate.) Even when every other civilization started denouncing me as a warmonger even though I didn't start it, I kept going. Eventually got her down to two cities. I took the one closest to me, renamed it to Fart City, then offered it back to her in exchange for peace which she gladly took.

Then I waited a few turns until it had cooled off, then declared war on her again. This time I took the city on the other side, leaving her with Fart City and about three workable tiles, completely surrounded within my territory. I stayed at war for the entire rest of the game, with troops completely surrounding her. Every time she built an improvement I instantly pillaged it, ever worker was instantly captured, every troop immediately blasted. She just got to live out the next thousand years or so in squalor in Fart City, while every other country denounced me for my crimes lol.