In my most recent game, I had the biggest empire among all and my late game was going well and nice, no wars, no problems.
Then I decided to attack the aztecs. They were on a continent south of my empire, and they were the least advanced civ. I infiltrated a spy and got to look their military. I said to myself: "Alea jacta est"
and started to pile up large fleets near their northern shore. Meanwhile, I signed a mutual protection pact with the romans, who were on the opposite side of the aztecs. If the aztecs decided to send troops to attack me on my territory, then the romans would intervene, just in case... I feared that I could not sign a military alliance with the romans against the aztecs.
And during all these "warm up" turns, I kept giving the aztec some gold; they could never know what was about to break upon them!
Finally, I trespassed their borders. Montezuma came in a hurry: "your troops blah blah blah...". I said: "Now it is too late for these diplomatic bullsh!t, mister...". And then I took two aztec cities. I managed to sign a military alliance with the romans, and they took other two aztec cities. Then... I gave up! Yep. I saw Montezuma's sad look on the foreign advisor screen; I had a sudden regret. He had always been good to me. How could I treat him this way? Sorry, Monty.
We made peace. And how I wanted Civ3 to have a "please-make-peace-with-this-civ" diplomatic option, so I could tell the romans that Monty was a good pal.