Kingsmill massacre: Ten Protestant workmen were killed in County Armagh, Northern Ireland, by members of the South Armagh Republican Action Force, after loyalists shot dead six Catholic civilians in South Armagh the previous day.
3 April – The last passenger train ran on the Limerick–Claremorris line ending an 80-year north–south link along the western seaboard.
May
17 May – Tim Severin and his crew set sail from Dingle to America in the leather boat Brendan, tracing the route of the legendary 6th-century Irish monk, Brendan the Navigator. The Brendan reached Canada in June 1977.
June
29 June – The 20th century's highest temperature record in Ireland was 32.5 °C (90.5 °F) at Boora, County Offaly. The overall highest on record was in 1887.[1]
July
July – The rock band Horslips gave a rooftop performance from Bank of Ireland headquarters on Baggot Street in Dublin.[2][3]
15 July – Four prisoners escaped when bombs exploded in the Special Criminal Court in Dublin.
21 July – Christopher Ewart-Biggs, UK ambassador, and a civil servant, Judith Cooke, were killed by a landmine at Sandyford, County Dublin.
September
1 September – The state of emergency in the Republic, which was legally in force since 1939, was lifted.[4]
23 September – The President, Cearbhall Ó Dálaigh, consulted with the Council of State for four hours on whether to refer the Emergency Powers legislation to the Supreme Court.
October
22 October – President Ó Dálaigh resigned following insulting remarks by the Minister for Defence, Paddy Donegan, who called him a "thundering disgrace".
27 October – A new £5 note was introduced bearing an image of the 9th-century philosopher, Johannes Scotus Eriugena.
November
20 November – National Peace Day was marked with marches, church services, and bell ringing.