Political map of Europe & the Mediterranean 28 June 1922 (Irish Civil War): The Irish War of Independence from the British (Irish War of Independence) ended in December 1921 with a treaty (Anglo-Irish Treaty) dividing Ireland into two parts: a largely protestant north ruled by Britain (Northern Ireland) and a mostly catholic self-governing dominion in the south (Irish Free State). Many Irish republicans saw this treaty as a betrayal and in June 1922 clashes between these extremists and the new government in Southern Ireland led to war (Irish Civil War).