Writing in 1771, Bishop Philip Philips imagined that the episcopal succession of Killala would be easy to trace;

'The Church of Killala was founded by St. Patrick about the year 440 and to it, he gave as first bishop, Saint Muredach. To him there were successors, but how many there were and of what kind is not known up to 1151. From the year mentioned, however, up to the present it would be easy to trace the series of Bishops of Killala, noting that in some ages formerly they were called 'Killala', in others 'Tirawley', occasionally, but rarely, 'Fiachrenses', these various appellations having been taken from the various surrounding territories.'

But, as Bishop John Mac Hale discovered on his visit to the archives in Rome in 1831, tracing the stem of Killala's episcopal succession was no easy task. The notices of the lives of the Killala bishops, he discovered, 'are but scanty nay, it would be difficult to supply some considerable chasms with their very names'

In the second of three volumes of Readings in Killala Diocesan History, Brendan Hoban attempts to record what data is available on Killala's bishops and to profile a varied compendium of individuals who occupied the seat of St. Muredach from earliest times.

From the historian Tíreachán in the seventh century to the saintly Francis Kirwan in the seventeenth, to John Mac Hale in the nineteenth and to John Fleming in the twenty first, 'Trcing the Seam, Killala Bishops, offers as comprehensive a listing of Killala's bishops as present research allows.