Maybe it's just me, but it seems like getting military alliances is too easy--often AI civs will flatly refuse to trade me tech or resources, but will happily invade at my behest nearer and far more powerful civilizations for a few hundred gold (the equivalent would be Al-Qaeda convincing Canada to invade the U.S. on the promise of a few million bucks!). This is nice when I need some help, but it's also quite annoying when the AI teams up with each other.
In my current game, I played as a friendly tech-trader & had Polite relations with each of the ten other civilizations in the game all the way up to 1870 A.D.--not a single war or diplomatic transgression on my part. Then I told a foreign unit that had trespassed into my territory to leave (like I'd done many times before) and that civ immediately declared war on me--over the next few turns, a cascading alliance led to 9 of the 10 civs declaring war on poor, peaceful little old me (I think I'll be able to hold out for a couple of decades before getting wiped out)! I guess what I'm saying is that it seems odd there's no way to really build up goodwill over time or to ensure peace other than with a mutual protection pact (which will likely get you drawn into wars with other civs).
In my current game, I played as a friendly tech-trader & had Polite relations with each of the ten other civilizations in the game all the way up to 1870 A.D.--not a single war or diplomatic transgression on my part. Then I told a foreign unit that had trespassed into my territory to leave (like I'd done many times before) and that civ immediately declared war on me--over the next few turns, a cascading alliance led to 9 of the 10 civs declaring war on poor, peaceful little old me (I think I'll be able to hold out for a couple of decades before getting wiped out)! I guess what I'm saying is that it seems odd there's no way to really build up goodwill over time or to ensure peace other than with a mutual protection pact (which will likely get you drawn into wars with other civs).