Line in the Sand

Typically when I play any game of Civ, and especially multiplayer, I try to work with people. I'm not overly aggressive, but I'm prone to take a few nearby city states in the early game, which I think is reasonable. In my last game (multiplayer) I was Germany and I had taken a city state to my south, and I was pushing against one 8 tiles to my north when Venice told me to back off. I checked the screen and they were close allies, so I conceded. There was a second cs (Florence I believe) 3 tiles south of that anyway, so I went to take that one. Suddenly the other cs was flipped a la Merchant of Venice, and Venice bought up Florence and promised it protection. I naturally declared war.

So when do you draw the line? Do you push a little more aggressively on territory that is clearly in your hemisphere, or do you try to work things out until it's too late? I don't want to appear to look like a warmonger, but I also don't want to jeopardize my nation...

On Multiplayer, I probably wouldn't want to risk a very early war over a city-state. That'll just mess with your momentum. On single player, go buy an ally and crush any fool that settles near you. At least one AI won't get pissy over it.

If it's in my sphere of influence, they will just have to deal with it.
They can go to war against me if they don't like it.

And plus if they just paid for allied status with florence, chances is that Venice player is now vulnerable and out of gold which you can use to press the city state and smack it before it can buy the walls and castles if it became venice land that is. Otherwise. Smack it hard, what is venice gonna do? Whine?

You could just point out that you let him have the other city state and then he tried to keep the 2nd away from you and you didn't like that cuz he got too greedy. Or Coup it away from him for lols and sincerely claim that you need the culture from florence. Bonus points to you if his agent die in counter coup to your agent. xD

In multiplayer there are no rules of conduct. If you think you are in a better position than the guy next to you then you do what you want. If you think he could crush you then you need to be diplomatic.

Generally I do what's best for me and hope my neighbor doesn't get too upset. If I do something to annoy them, I make sure that I have good production and military techs so that I am prepared if they choose to do something about it.

If you are prepared for an incursion and they know you are, the chances of them doing anything to you are much lower. Most people want a quick, swift victory. They know that's not going to happen if their target is prepared.

when the AI builds a city with 5 or 6 tiles of your capital and it's nowhere near their own territory. Especially early on when they are spamming cities.

It's just provoking war