There's also a point to be made on AI peace making. It can appear at current that the AI isn't making peace with neighbours. The AI does in fact make peace with other nations, but the player is not notified directly of these events. The status of relationships between AI nations can be found in the diplomatic screens, and AI nations are in fact making peace as well as declaring war. However there is no 'event message' for this.
Yes, really, cut the BS... I have had several campaigns where I dragged an AI nation (my ally) into war with some remote faction at the start of the game. After a few turns, I make peace with the target nation. However, my allies stay in the state of war with the target nation indefinitely in the game terms despite not carrying out any hostile actions (actually fighting). I have even stopped bothering 'inviting my allies' when I declare war on the target faction for the second/third/fourth time since I always know, my allies would still be at war with the target...