I did more investigation to find out what happen in a.i. behavior through war and happiness. Most of you know that before 1.29 a.i. switch commi pretty soon in war and collapse later on by drafting to much. So firaxis did something to fix that.
In my last game ( regent, std continent map, against 4 a.i. ) i wipe out aztec and iroquois pretty soon with knight and drag grece into this war with an alliance. Those 3 a.i. were on my continent and chinese left alone on a middle size continent. I wage my war as a monarchy and conqiere or built 24 very good city in medieval era.
Later on Grece declare war on me ( i was democraty ) but my cavalry kick their but, i raze 3-4 of their city and then stop my invasion to keep them alive, i drag chinese into war with them with an alliance.
here what happen, they wage war within themselve from 600 A.D to 1700 A.d and they were both democraty. So i investigate their city to look about their happiness, i saw a grece city size 12 with 6 entertainer and starving 4 food. This city had temple, cathedral,coliseum inside of it and 2 luxuries.
Around only 1800A.D grece switch commi and chinese republic ( i was selling them luxuries to help them).
So this kind of behavior is pretty strange, for sure their city wont riot and wont smoke like before but they wage war as democraty and create bunch of entertainer to a point of starvation. So their city become very weak.
I easily won a space race in 1900 while they were in the middle on industrial era.