Like all civil wars, this one was marked by bitterness and atrocity. Collins was forced to organize an official military response against the same IRA men he had fought beside for years. Hundreds died, and Collins himself was killed in an ambush. The anti-treaty forces, however, did not have the support of the populace, and it was soon clear that they could not win. To stop the bloodshed, Éamon de Valera announced that it was time for Ireland to accept the treaty and move on.

Ireland had peace and independence at last, but not without a cost. The scars of the Civil War haunted Irish politics for decades. More significantly, the division between the Irish Free State in the South and Northern Ireland had become real and immovable. Unionists in Northern Ireland, appalled by the violence of the Anglo-Irish and Civil Wars, resolved more strongly than ever to remain part of the United Kingdom. This unnatural division between North and South has plagued people on both sides of the border to this day.