Lord Parkin
aka emperor
As I recall, you have to have a city located such that the connection between the two rivers is inside your borders for this to work. For instance, founding a city further down the river in the screenshot would result (I think) in the cities not being connected. Can anyone confirm this?You play Vanilla, and in Vanilla you don't need Sailing for river trade; it's automatic. Both cities are adjacent to connected rivers, hence they act as trade conduits to all cities on those rivers.

Indeed. And if that one unit is a Spy, then you can't do a thing against him and have to simply hope that he gets caught soon. I find that Require Complete Kills is really only an option that works in the multiplayer environment, for a couple of reasons. Firstly, because human players could feasibly have decent stacks which could capture back a city even if they've lost their last one; and secondly, if it's something like just a Spy or Caravel remaining, the human player can choose to delete their units if it's futile and save the other player having to hunt them down for ages.Yes, it could be anything. As long as he has some unit which can be anywhere on the map, then he'll live. That's the disadvantage of the option.