Here is an example of what Jim is talking about. And it happened in the late 70s. The height of the Troubles. I wasn't there to witness this, but my (English-born) husband was.

Michael had won the All Britain Fleadh in bodhrán, and this entitled him to compete in the All Ireland, which was being held that year in Buncrana, Co. Donegal - only about 12 miles or so from the Derry border, with Derry city just beyond it.

The Irish of all stripes love their music, and they're good at it. One reason for this is that a lot of the children start playing very young, schools are fertile breeding ground, and a natural thing to do is form them into marching bands. And marching bands mean parades.

So: a Fleadh, loads of talented kids with instruments, and a deep division between Orange and Green, over which people are dying regularly just the other side of the Foyle. Hence, there would be not one parade, but two. Starting at opposite ends of the town, each heading towards the centre. At the same time. A Catholic band striding down the high street from one side, a Protestant one from the other, both playing their music at full blast. High Noon in Buncrana.

Michael watched with mounting unease as the two sides kept moving relentlessly towards the middle, approaching nearer and nearer until they faced off, and...

marched through each other. In organised lines. Never dropped a step, never missed a beat, never fluffed a note. Straight. Through. And on out the far end, the two tunes mingling in the air behind them.

Michael says he never saw anything like it.