Civs automatically declaring peace?

[vogg]

So I was playing with Ghandi, attacking Berlin with 3 War Elephants. By the time Berlin had a sliver of health left and I was about to destroy it, the final hit does no damage and the turn after he declares peace with me without my consent!

I reloaded my savegame and this happened time and time again. The weird thing is that in the deal history of the diplomacy tab there are no recorded actions.

Am I missing something? I tried declaring war with all my allied city states, but this didn't help either.

 

[DutchLuke]

In several games in which I, Ramses attacked Darius' Persepolis with more than enough units, the same happened to me.
When Persepolis was about to be taken next turn, in the following turn, peace was declared without my consent.
I played with 4 allied citystates and agreements of cooperation with two civs...
what is wrong?