The Irish National Liberation Army (INLA) was a breakaway group from the Official IRA, made up mainly of those unwilling to accept that group’s decision to suspend its military operations in May 1972 and unwilling to betray their socialist principles by joining the Provisionals. A new political party, the Irish Republican Socialist Party (IRSP), under the leadership of Seamus Costello, was set up by these dissidents at a meeting outside Dublin on 8 December 1974. By the afternoon of that day an armed military wing of that movement had come into being with Costello as Chief of Staff.

What probably catapulted the INLA to prominence was its assassination on 30 May 1979 of Airey Neave, one of Margaret Thatcher’s closest political supporters. It was deemed to be the most ruthless of the Irish terror organisations, but within a decade the group had degenerated through a series of splits, internal feuds, with the warring factions killing each other to such a degree that by the late 1980s it had virtually ceased to exist in its original form. In saying this issues, statements and warnings from the group still pop up in Belfast and elsewhere.

The INLA gained a propaganda victory when they killed LVF leader Billy Wright also known as "King Rat."

For a more detailed account of the INLA see Jack Holland and Henry McDonald’s book, INLA: Deadly Divisions, Torc, Dublin, 1994.