Seamus Costello

Seamus Costello
Seamus Costello
Séamus Mac Coisdealbha
	Costello during a December 1975 interview with RTÉ
Wicklow County Councillor
	In office; March 1967 – October 1977
Constituency	Bray
Bray Urban District Councillor
	In office; 1977–1967
Personal details
Born	1939; Old Connaught Avenue, Bray, County Wicklow, Ireland
Died	5 October 1977 (aged 37 or 38); North Strand, Dublin, Ireland
Manner of death	Assassination by gunshot
Party	Irish Republican Socialist Party
Other political; affiliations	Sinn Féin (1955–1970); Official Sinn Féin (1970–1974)
Spouse	Maeliosa Costello
Children	4
Nickname	The Boy General
Military service
Branch/service	Irish National Liberation Army (1974–1977); Official IRA (1969–1974); Irish Republican Army (1955–1969);
Rank	Chief of Staff (INLA); Director of Operations (Official IRA); Adjutant-General (IRA);
Battles/wars	Border Campaign; The Troubles;

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Seamus Costello (Irish: Séamus Mac Coisdealbha, 1939 – 5 October 1977) was an Irish paramilitary and politician. He was a leader of Official Sinn Féin and the Official Irish Republican Army and latterly of the Irish Republican Socialist Party (IRSP) and the Irish National Liberation Army (INLA).

He argued for a combination of socialist politics on economic issues and traditional Irish republicanism. He is best remembered for the founding of the IRSP and the INLA. He was a victim of a feud with his former comrades in the Official IRA.