What other said: Start wars of deception elsewhere long away from your intended target. I've found it most effective that if I for example want to conquer some Baltic pagans, I declare war on some muslim country and watch the king sit down and leave with his transports for the Holy Land. This is great, because even if he changes mind and wants to kill some pagans instead, he will still be halfways to the middle-east by then. Additionally I don't think the AI in CK changes any movement which is by sea, and this eans the king will not go back until he ended up of the shores of a big desert.