I'm hoping this thread will over time develop into one that answers all questions about invisible units. So far, I've found out that (please do correct me if I have any of these 'facts' wrong ): 1. Rogues can be seen by dog units and other invisible units. Other animals and animal units can't currently see them. 2. If one of your units can see a rogue, all the others can see them also. You can use a stronger/better-promoted/more expendable unit to attack them allowing your dog/rogue to live to discover a rogue another day. 3. If a unit moves onto the same tile as a rogue, nothing happens (unless it is from a civ that can see that rogue). However, if a rogue moves onto a tile with a unit of any other civ, combat ensues - it can't do this invisibly. However: - this is not always the case in cities. A rogue can enter an enemy city without engaging any units in the city. Which brings me to my two current questions: Q1: Can a rogue enter a foreign city (with units in it): - only if its civ has Open Borders with the city's civ; or - only if its civ is not at war with that civ; or - at any time regardless Answer: the best (only) answer so far is that a rogue can enter a city as long as no unit in the city can see it (thanks DH). DH does not seem entirely sure, so if anyone else can confirm this, or has a confident opinion on this, I'd love to hear from them Q2: How do you get rid of a foreign rogue in one of your cities? - by cancelling Open Borders (I don't think so); or - by declaring war (on everyone as you don't know who the rogue belongs to); or - there's just no way to do it Answer: DH's answer (thanks DH) is that there is no way to get rid of a foreign rogue in your city. As a result of that answer, I'm afraid I have to add some more questions... (see Q4 & Q5) StrategyOnly (thanks SO) has raised the option that, if you have the 'Opportunity Fire' option in RevDCM enabled, and have attacking siege weapons (cats/trebs/ballistae I presume), they can attack invisible units in your cities. Not sure about this personally. More details as they come to hand, as they say. Q3: Just out of curiosity, and possibly as something for you to think about, can a rogue visit a civ that does not have contact with its civ? Or does its visit trigger contact even though one civ is unaware of its presence? Q4: You can't do anything about rogues once they're in your cities: is this seen as a bug or problem by the development team, and if so, is anything being done about it? Answer (thanks JosEph II): It is not seen as a problem - just build anti-crime and wait till he gets bored and leaves (However I did see a comment in another thread that someone was looking at the possibility of a mechanic for forcing the rogue out) Q5: What can a rogue do in your city? He will cause the crime rate to rise just by being there - can he do anything else eg. missions like a spy or assassin? Answer (thanks JosEPh II): Rogues can't do spy/assassin-style missions - they only raise the crime rate (Note to self: so the haemorrhage from my treasury is either due to the said crime rate, or is for some other reason entirely) Edited to add that there is a whole variety of other units with which you can have similar problems. Aoklo (thanks aoklo) points out that there is a range of bandit units, as well as a 'Warlord Chief' - these can also enter your cities if you don't have dogs.