If you kill loads of them to start with, you reduce the population, but it will repopulate (slowly) with people from your own nation, and will be happier.
It takes a while to repopulate though, and in that time output and income form taxes are all reduced. I think there is a middle option, I can't remember.
I only totally wiped settlements in Medieval - i was retuning from a crusade, and there was no way I could keep hold of the settlements I took, as i was so far from home with no hope of reinforcement, and lots of angry locals.
So I took them, sacked them, and razed every building for the money. Then moved out. It paid for the army upkeep if I took one each turn, and it crippled the enemy as they had to retake and rebuild everything.
The happiness thing becomes a big thing in Rome - if you haven't built the right things, all your settlements start to revolt, just as your armies are miles away trying to mop up the last of the campaign.
@Cause. I meant the carronade technology, not just the carronade unit. I was assuming all your ships would get carronades on their top deck? And would be far more effective in naval battles.
This post has been edited by Traveller: 07 April 2009 - 11:44 AM