- Republicans sweep the elections but refuse to take their seats in Westminster.
- They convene as the Dáil Éireann in Dublin.
- Height of the War of Independence (1919 to 1921), in Dublin's Croke Park football supporters are shot by British troops during "Bloody Sunday".
- Reign of terror by the notorious "Black and Tans".
- Government of Ireland Act proposes partition.
- The Anglo-Irish Treaty establishes a Northern Irish Parliament in Belfast, partition and an "Irish Free State" ruled by the Dublin Dáil.
- Irish Civil War, the Anti-Treaty IRA and the Free State National Army are locked in open and guerilla warfare.
- Michael Collins is killed in an IRA ambush.
- Dozens of executions are authorized by the Free State.
- The civil war ends with the surrender of the anti-treaty forces.
- W.B. Yeats awarded Nobel Price for Literature.
- G.B. Shaw awarded Nobel Price for Literature.
- Fianna Fáil (founded in 1926) sweep the general elections under de Valera.
- The fascist "Blueshirts" emerge but are soon absorbed into the new United Ireland Party (Fine Gael).
- The Irish Free State bans the import and sale of all contraceptives.
- The Irish Free State bans the IRA.
- Constitution of Éire declares independence from Britain.
- The Irish Free State ceases to exist.
- Britain returns "Treaty Ports" to Éire.
- Just before the outbreak of World War 2 the IRA starts a bombing campaign in Britain.
- Éire opts for neutrality in the war, but with "a special consideration" for Britain.
- IRA prisoners on hunger strike starve to death in Éire.
- Major German air raids on Belfast.
- Accidental bombing of Dublin.
- De Valera alienates Allies by personally offering his condolences upon the death of Adolf Hitler.
- Republic of Ireland declares full independence.
- De Valera loses election after 16 years in office.
