In one of my lectures the professor said that there are two main ideas for the true purpose of Medieval British castles: the first was that they were defensive and could hold seiges and kept the royalty in them and people lived there, the other was that it was just a show of power and intimidation for the enemy, and only to be used as a last resort for defence. He was in the second camp, and I can see why both arguments are valid, but I couldn't find a lot of research to back him up. Here in Wales we have more castles than anywhere else, and I can see why castles would be built for defensive purposes (e.g. Pembroke Castle) and why it would be built for show (e.g. Chepstow Castle). So which is it?