Greetings.

One thing I can not figure out is how to handle contesting a region that is allied with another player. So lets say I won an intrigue contest and remove my emissary and place a tower piece. Next turn another player moves and army there to start a campaign. What happens now? Does he fight the nation to remove the ally tower? Does he simply start his campaign? Does he do nothing until one of his emissaries removes the tower via his own intrigue contest?

Got a round of this planned this weekend thanks ahead of time for your replies.

-Pan

It is treated as a siege (see page 16 of the Rulebook). In your example, you would defend the province with any army units you may have there. If you had none, you would defend with the province rating, and remove your tower if you lost.