Here's the situation in my last game: 3 races on the continent: me, japan and Rome. Rome is between myself & Japan. I have generally been playing peacefully all game, and Japan has been a douche. He has attacked me & Rome both a few times (separately) but not gained much traction against either of us. So I have been defending myself & hoping that Rome can do the same, as I do not want Japan to get the Roman land. Due to my luxury situation (8 ivory and barely anything else) I am trying to play peacefully & so I have not tried to conquer Rome. I have got along with them very well, with many trades and some DOFs. So, eventually (I think around rifling?) Japan starts having success in taking over Rome, finally. Rome's army breaks and Japan starts taking cities. By this time my military is advanced as well, so I kind of want to join in the war and take half of Rome's land. However I am still concerned about diplomacy and taking the back-stab/warmongering hit, so I do not. Next thing I know, Rome declares war on me! Totally out of the blue, and there is absolutely nothing to be gained from it. My military is far superior and they are being invaded in another front. The only possible outcome for them is that it hastens their demise. So, the only thing left in my head to explain this, would be they want ME to have their cities/land instead of Japan. Basically they hate Japan more than me, so they would prefer I take some cities instead of Japan taking them all. That's what I went on to do, splitting their empire between me & Japan. Does anyone know if this is true? It's very humanlike behavior (childish almost) but I was suprised to see an AI act that way. Maybe there is another factor I am overlooking? Any ideas?