Interdiction

[Sarxis]

I am thinking about how plausible it is to stop AI expansion by means of interdiction. Unfortuntely, the AI seems to always escort its settlers with at least one military unit. Well, actually, that is a good thing, but still, lining entire stretches of land with a frontier of warriors might help with stopping AI expansion into lands you don't want to share; but is it really a cost effective idea?

[David Floyd]

Not so much early on, but what IS cost effective is finding a stretch of land 2 or 3 squares wide, the closer to an enemy the better, and shoving that area full of cheap defensive units...they have to go to war just to expand, and since you have strong defensive units there they will lose more than you even getting out...even more so if you shove some settlers out there and build a chain of 2-3 cities behind your defensive line...I did that to the Germans in my current game, totally bottled them up so that they only have like 6 cities on the main continent except for two piddly outposts they sneaked past me that I'm about to culturally annex. Stupid bastards

[Admiral PJ]

Can't you use new cities to block expansion routes by the enemies? With a lot of culture their big borders should help stop anyone coming through too (tell them to go to hell -leave your country if they decide to trespass on your backgarden).
Small newly built cities are vulnerable too.. so when they start expanding make sure your there to beat them early before they put up a wall and get that city sized 50% bonus.
Someone else had the idea of building up a city with lots of workers to increase pop points.. should help build up these blocing cities to prevent from being overrun by culture suberversion.

[Kc7mxo]

Unfortunately to use cities effectivly you need to rais their culture, and they'll still sneak through.

Plus in my experience the AI is quick to use ships to slip settlers to gaps in your territory.