War as a unifier

The Revd Canon Dr Giles Fraser mentioned in his Thought for the day address on Radio 4's Today Programme  this morning the idea that wars are fought abroad as a way of trying to bring unity to a country. He didn't say that this is the only motivation for war, and perhaps he wouldn't argue that, but it is unusual to hear such a view put forward in the mainstream (at least in my experience). More usually war is portrayed as protecting us from attacks against our country and way of life.