can i move troops across water in the campaign?

[Alexios]

I tested this last night, and yes, you are very right Kvhan. Thank you for correcting me. It's funny, I've never noticed this before. But I have always played as English or Byzantium, so I guess I've always had enough land mass in front of me to keep me busy.

But as far as sea battles go, I always try to build up my navy as soon as possible from the very beginning of the game, and hopefully establish superiority in the seas. Once I have done that, then I begin attacking the faction in the water until I have cleared the lanes to the province(s) I want to conquer. Playing as the Danes, however, I am sure it would be very difficult to establish such superiority, at least in the Early and Middle periods, anyway.

Another tactic I thought of that might help a small faction looking to expand overseas, is to attack a coastal province controlled by rebels. The AI does not build ships for rebels, at least none that I've ever seen, anyway. So you would have free passage to attack their province, providing you don't have any other adversaries blocking your shipping lane. This would help you get established on another continent, and thereby expand from there.