Another institution, closely connected with the twelfth-century reform and with the name of Malachy, which was to become a casualty in the thirteenth century, was the primacy of Armagh. With its undermining went the de iure unity of the Irish Church, in particular the possibility of all the bishops of Ireland meeting together for the good of the whole ecclesia hibernicana. This disunity, reflecting both the particularism of Ireland itself and the post-Invasion national divisions, must be given significance as a factor impeding further progress in reform of the Church.

Armagh of course owed its traditional seniority to its association with St Patrick. As the pope was heir of St Peter, comharba Peadair, so the prelate of Armagh was heir to the founder of Christianity in Ireland and his established title, comharba Padraig. All the schemes of diocesan construction of the twelfth century envisaged the preservation of this seniority and planned an unquestionable primatial prerogative for the see of Patrick. At the council of Rathbreasail in 1111, as reported in the lost Clonenagh annals, Armagh signed as archbishop and as primate of all the bishops of Ireland. At Kells in 1152, though four metropolitans were now constituted, Armagh was designated, according to one source ‘in primatem’ and according to another, ‘primas tocius Hibernie’. There can be no doubt at all that it was intended, and intended by the pope whose legate presided at Kells, that Armagh should have the senior position and enjoy place as first of the bishops of Ireland.