11 February - The last armed rebel group of the Society of United Irishmen, led by James Corcoran, is betrayed and killed or captured by yeomen near Enniscorthy.
4–5 March - Castle Hill convict rebellion in New South Wales led by Irish convicts in Australia.
April - First boat passes through the Grand Canal throughout between the River Liffey in Dublin and the River Shannon.
14 May - Cork Street Fever Hospital, Dublin, opens in Cork Street, Dublin.
First Martello Tower erected in Ireland, at Sutton, Dublin.
Early February - James Bronterre O'Brien, Chartist leader, reformer and journalist (died 1864).
4 April - Andrew Nicholl, painter (died 1886).
7 April - James Emerson Tennent, politician and traveller (died 1869).
18 November - John George, politician, judge and in 1859 Solicitor-General for Ireland (died 1871).
25 December - Frederic Trench, 2nd Baron Ashtown, peer (died 1880).
26 December - Sir Joseph Napier, 1st Baronet, Conservative Party MP and Lord Chancellor of Ireland (died 1882).
31 December - Francis Sylvester Mahony, humorist and poet (a.k.a. Father Prout) (died 1866).
February - James Corcoran, rebel leader (born c.1770).
27 July - Robert Clements, 1st Earl of Leitrim, politician (born 1732).
1804 in Ireland Wikipedia
Events from the year 1804 in Ireland.