cavemanf16
Grand Poobah

Now, there are some caveats inherent in using the strategy to breaking a Mutual Protection Pact (MPP) that I have devised. This may not be a revolutionary technique for some of the experts on CFC, but I thought I'd go ahead and share it anyways.
You really need to be playing as a Religious civ for this strategy to be most effective. It will work with other civ's, but may not be worth the lost production of multiple turns in Despotism (I'll explain this later).
In my current game as the Japanese (Religious/Militaristic civ) on Monarch level, I stumbled across this technique. It's actually happened before, but never was as useful or noticeable to me since I normally don't play Religious civ's.
Let me explain the setup to the technique. First, I began around 10BC, a conquest to take out my neighbor, the Indians. After about 20-30 turns, Gandhi's empire was no more.

Second, almost immediately after destroying the Indians, I decided to take on the Chinese. So now it's me (the Japanese), China, Zulus, Ottomans, Vikings, and Persia occupying the world. Sometime during my conquest of the Chinese, and taking on the Vikings, I researched Nationalism, and was able to get MPP's with the Persians and Ottomans who were the second and third most powerful civ's next to me (due to my recent conquests).
So Ive been at war nearly continuously for the past 2000 years or so wiping out one after another civilization.
When I finally defeated the Zulus around 1800AD, it was only myself, the Persians, and the Ottomans left, whom I still had MPPs with. Unfortunately, I wanted to keep conquering one of the two civs to go for the Domination or Conquest victory, but how to do that without pissing off my other MPP ally when I invaded the unlucky new enemy I decided to take on first. (At this point I had decided I needed to take on the Ottomans first as they had more trade goods I could use, and were less scattered all over the world as the Persians were)
I decided to go ahead and build up my military, and wait until I researched far enough to acquire Tanks as my primary attack weapon, as everyone had Infantry and as we all know, Infantry is prohibitively tough to win against without lots of artillery and tanks. Since I was in a Communist government, I knew going to a Democratic government would allow me to grow faster and stronger while saving up for my immenent attack on the Ottomans. Plus, since I was a Religious civ, it would only take one turn to flip governments.
Now a curious thing happens when youre very powerful, and you decide to switch governments, and the AI players are few: they LOVE to attack! Ive noticed this many times in other games Ive played, but it never worked too well because it usually took 5-10 or more turns for me to change governments, giving the AI 10 turns of nearly unstoppable attacks on my various border cities. This time around however, because I was in MPPs with both Persia and the Ottomans, I now once again have a Polite Xerxes on my side against the Ottomans (Xerxes was Cautious due to my warlike nature and the fact that only him and the Ottomans were left for me to go after). The Ottomans broke an MPP with me, thereby ruining their rep with Persia, so I can remain relatively confident that Persia will stick with me until the bitter end of the Ottomans, at which point I can turn my sights to killing off the Persians to achieve world domination.

Hope this strategy works for you!