12 July - Olivier Plunkett was born in Ireland on 1 November 1629. He was brought up by his Benedictine uncle in Dublin. He then went to Rome to study theology. At the end of these studies, he cannot return to his country because of the persecution unleashed by Cromwell and remains in Rome for three more years during which he exercises his ministry there.

Then, for twelve years, he taught at the college De propaganda fide. Ordained a priest in 1654, he was not appointed Archbishop of Armagh until fifteen years later. He exercised his ministry with courage, devotion and good humour.

But in the context of Anglo-Irish quarrels, he is slandered and accused by an intriguing man, Titus Oates, of having prepared the landing of 20,000 French soldiers in Ireland, in addition to having demanded money from his priests to create an army of rebellion. Transferred to London in 1678, he remained in prison for three years before being sentenced to be "hanged, gutted and dismembered". Throughout the tortures he had to endure, he never ceased to give thanks to God, forgiving his denouncers and executioners. Saint Oliver thanked the judge and said to all those who had slandered him: "I am happy to go to Christ of whom I have told you so much".

He died on July 11, 1681 in London. Charles II, who knew he was innocent, returned his remains to his loved ones for a decent burial. His body lies in Downside Abbey, County Wilts, while his head is enshrined in Drogheda. He was the last Catholic to be martyred at Tyburn. Olivier Plunkett was beatified on 23 May 1920 in Rome by Pope Benedict XV. He was canonized on October 12, 1975 in Rome by Pope Paul VI.