The campaign against government forces by the Irish Volunteers, now known as the Irish Republican Army (I.R.A.), it lasted from 1919 until a truce on the 11th of July 1921 opened the way for the negotiation of the Anglo-Irish Treaty.
By permission of Oxford University Press
Connolly, S.J. (Ed.) The Oxford Companion to Irish History Oxford , O.U.P., 2nd Edition, 2002