My First Intercontinental War, who should I attack?

[Skallagrimson]

Human players might do this. However, in non-vassal cases I've encountered exactly 0 cases of an AI giving another AI a tech for nothing, even to avert easy wars.

What you describe is, however, possible as part of a war bribe aka "i'll give you assembly line if you dow the human". THAT is a pretty big threat. The AI giving monty rifling or AL for absolutely nothing? Not so much.

Maybe I'm just lucky. I'll be happily romping all over backward cities defended by LBs with my infantry, and then *without* a DoW from a high-tech AIs, those LBs are suddenly at least rifles, sometimes infantry. Rifles are still not a problem, just more annoying, but when impi spam becomes infantry spam, zoiks shaggy!

That tech came from *somewhere*. I don't know what exactly the payoff may have been but I've always assumed the high-techer AIs had a strategic interest in seeing my invasion fail.

One other possibility though is that if, early in the war, a huge aggro Monty for example, demands AL from a high-techer, which for whatever reason decides it's better to give (techs to Monty) than to receive (Monty cuirassier tidal waves). It's not a choice I make, but the AIs do it all the time.