Conflict was never inevitable until late June so why did the Civil War happen?

War among comrades could have been avoided, writes John Dorney

A member of the National Army stands guard at a window armed with a revolver, circa 1922. Picture: Independent News And Media/Getty Images

WHY was there a Civil War in Ireland in 1922-23? Why did those who had been comrades in pursuit of Irish independence over the previous four years begin killing each other over the Anglo-Irish Treaty?

The short answer to this question is that irreconcilable differences over the Treaty divided them. But the recourse to arms was not inevitable, and the internecine bloodletting was deeply unpopular with the public. Why then, did it happen?