So, I was playing Civ 5 as Harun al-Rashid, having trouble with China to my east and trying to be friendly to Montezuma to my south. But after I settled China by destroying their invading army, Montezuma double-crossed me and invaded himself. It was difficult defending because I had just finished a war; at one point I had to pay 300 gold to quickly build a Wall around my southernmost city to increase its defensive strength. (I normally try to avoid spending ANYTHING on military early in the game, as it slows down growth.)
But this gave me a goal. Montezuma offered peace if I would pay him off with gold and resources, but I declined.
A little later, he offered peace for free. But I declined again.
Finally, as I was pushing into his territory and threatening to take one of his cities, he offered peace with 52 gold now and 11 gold per turn for 25 turns (52 + 275 = 327 total). I accepted because it achieved my goal, which was to get at least 300 gold from him.
That’s right: I built a Wall, and I got Mexico to pay for it. 🙂
Energy and Time 