It was the brainchild of Paul Cullen, Roman Catholic Archbishop of Dublin and future Irish cardinal.
He created it in 1872 to link growing public interest in politics and Irish nationalism with a Catholic agenda.
It was his second attempt to create a Church-orientated political party, following the collapse and failure of his first such organisation, the National Association.
The Catholic Union rapidly disintegrated, with members drifting away within a short time of its foundation.
Its failure, along with the failure of Catholic Church-created or supported parties and candidates, notably the disastrous[clarification needed] failure of the Bishop of Kerry's candidate in a Kerry by-election in 1872 (who was defeated when Kerry Catholics voted for a Protestant Home Ruler despite condemnation from the bishop), and the collapse in the campaign of one of Cullen's supporters in Meath in the 1874 general election (where the candidate was forced to humiliatingly pull out through lack of support), indicated the limits on the political influence of the Roman Catholic Church in late 19th-century Ireland.