Amphibious Galleys

[Meteor Man]

Once, while playing an epic game, and enemy galley was sailing past my coast when it suddenly and deliberetly attacked one of my coastal cities!
Luckily they lost, but it was the wierdest thing I have ever seen.

Does any body have an explanation?

 

[Northen Wolf]

Ai can declare war if you got priviteer in your harbor while it is only unit, Ships can attack ships in harbors. (Atleast they bomb your cities when you got priviteer in undefended city).