If Martin McGuinness had met Martin Luther King, he would have advised him and to abandon the peaceful, dignified protests that led to full civil rights within a few years, and to start exploding huge bombs in malls, bars and bus stations, and to shoot policemen and National Guard in the streets and in their homes on or off duty.
In NI that policy drove the communities even further apart and delayed a peaceful, equitable settlement for half a century.
We could have had it in the 70s.

The number of deaths, scaled up to the US population, would be comparable to the Civil War.