Born in the Earldom of Desmond as a member of the local Gaelic nobility of Ireland, O'Hurley was sent to Catholic Europe to continue his education, where he eventually became a professor of the Classics, philosophy, theology, and the law at the University of Rheims during the Counter-Reformation.

After a secret and underground religious ministry to both his fellow Gaels and the Old English population of The Pale, O'Hurley voluntarily surrendered himself in order to save one of his lay protectors, the Baron of Slane, from being imprisoned and executed in his place.

After he was first imprisoned and tortured by being "put to the hot boots" in Dublin Castle, with the full knowledge and approval of the Queen, by Lord Justices Adam Loftus and Henry Wallop, Archbishop O'Hurley was sentenced to death by a drumhead court-martial.

Due to the wealth of surviving documentation, Archbishop O'Hurley was considered one the most promising causes for Roman Catholic Martyrdom during the successive Apostolic Processes held in Dublin between 1904 and 1930, after which the results were submitted to the Holy See.

[2][3] The future Archbishop is believed to have received a Classical Christian education rooted in the Trivium at the Catholic school overseen by his kinsman, Bishop Thomas O'Hurley, to whom he may have been given in fosterage, at the Cathedral and monastery founded by Saint Ailbe of Emly.

[4] In 1551 he graduated with a Master of Arts degree, then a doctorate of Law and was appointed a professor of philosophy in one of that university's greater colleges, where he remained for 15 years and acquired a high reputation as a Renaissance humanist for his commentaries on Aristotle.

[7] According to historian Benignus Millet, who investigated O'Hurley's life in multiple European archives of the period, "The relevant registers and other records of Rheims University disappeared during the French Revolution.

[8] Although it was later claimed by Lord Justices Adam Loftus and Henry Wallop in their letters to Sir Francis Walsingham that Archbishop O'Hurley had been employed by the Roman Inquisition, this is not sustainable by other evidence.

Through their elaborate espionage system, the Queen's Court in London and her officials in Dublin Castle had immediate knowledge of Dermot O'Hurley's appointment to the See of Cashel, and Sir Francis Walsingham's spies and priest hunters were soon following his trail.

[7] O'Hurley's voyage was fraught with danger because of the state of war between the Pope and the Queen of England, but he accepted the risks involved and arranged for a sea captain from Drogheda to smuggle him from the French port of Le Croisic into Ireland.

Archbishop O'Hurley disembarked upon Holmpatrick Strand in what is now Skerries, County Dublin in the autumn of 1583[9] and was met by a priest named John Dillon, who accompanied him to Drogheda, where they lodged in a hostelry.

The Lord of Slane was exceedingly angry at the receipt of this letter & thought with[in] himself that it were a great point of discourtesy & contrary to the privileges of hospitality to apprehend a stranger who, never was in his house before, & thereupon did forbear to trouble and soon after went away.

As his nickname suggests, the Earl was a Protestant and had played a role in ending the Second Desmond Rebellion through scorched earth and total war that triggered a State-imposed famine, which killed an estimated third of Munster's population.

Meanwhile, Loftus, Wallop, and many other officials in Dublin Castle, greatly envied the Earl's favour with the Queen and kept him accordingly under constant surveillance in the hopes of implicating him in illegally tolerating Catholicism or in anything else that they might construe as high treason.

Despite the extremely high risk, however, the Earl of Ormond seems to have agreed to conceal and protect Archbishop Dermot O'Hurley, as long as he avoided matters other than his religious ministry and remained within the confines of County Tipperary.

Irish émigré chronicler Philip O'Sullivan Beare considered the Archbishop's arrest to be so heinous of an insult under the traditional code of conduct that the Earl should have raised the clans subject to him and taken up arms against Baron Slane and the Lord Justices.

"[22] According to Philip O'Sullivan Beare, "First he was brought before Adam, the Chancellor, and Henry, the Treasurer, and civilly and kindly invited to follow the tenets of the heretics, and promised large rewards on condition of abjuring his sacred character; relinquishing the office received from the Pope, and (O villainy!)

Dermot, not relishing this, especially as he was not allowed to reply to their nonsense, bade them, stupid and ignorant men (such was his high spirit), not to offer ridiculous and false doctrines to him, an Archbishop, and Doctor of celebrated academies.

[21] To everyone's shock, Archbishop O'Hurley refused to embrace Protestantism, "confess" to any political offenses, or "cooperate" with framing Baron Slane or the Earl of Ormond, whom Adam Loftus and Henry Wallop hated and envied, for high treason against the Queen.

[25] After the torture was finally ceased on fear that the executioner, Edward Waterhouse, might be punished for accidentally killing the Archbishop without orders, O'Hurley was returned to his cell inside Dublin Castle and received medical treatment from a fellow priest named Fr.

[26] When the Archbishop had recovered enough to sit up and to limp a little, the Queen's officials sent visitors into Dublin Castle, including Thomas Jones, the Anglican Bishop of Meath,[27] offering O'Hurley a high position within the Church of Ireland hierarchy in return for taking the Oath of Supremacy.

Meehan, "Foreseeing what his fate would be if arraigned before such a tribunal, twenty-four burgesses of Dublin, availing themselves of a statute passed in the reign of Edward IV, memorialized to have him delivered to them on bail, in order that he might have the benefit of common law, to which, as a civilian, he was fully entitled.

[32] Upon learning that the Earl of Ormonde, by whose influence and power they feared Dermot O'Hurley's life would be saved, was coming to Dublin Castle to congratulate new Lord Deputy Sir John Perrot, Loftus and Wallop decided to put the Archbishop to death as soon as possible.

[41] Power, the former Bishop of Ferns, who, after learning of O'Hurley's constancy, had returned to Catholicism and once again had again been imprisoned, too,[42] "called out aloud that he rather deserved that fate for the scandal he had formerly given, but that Hurley was an innocent and holy man.

Be it therefore known unto you (good Christians) that I am a priest anointed & also a Bishop, although unworthy of so sacred dignities, and no cause could they find against me that might in the least deserve the paines of death, but merely for my function of priesthood wherein they have proceeded against me in all pointes cruelly contrary to their own laws, which doth privilege any man that is worth ten pounds in goods not to die by Martial Law, which I leave between them & the Majesty of the Almighty & I do enjoin you (Dear Christian Brethren) to manifest the same to the world and also to bear witness on the Day of Judgment of my innocent death, which I endure for my function and profession of the most holy Catholic Faith.

[45]After "so desiring them to join with him in prayer recommending his soul to God",[48] and "forgiving his torturers with all his heart",[41] Archbishop Dermot O'Hurley was turned off the ladder and hanged, allegedly from a noose woven out of willow branches in order to further prolong his sufferings by causing a slow death from strangulation.

His body was secretly exhumed, placed in a wooden urn by London-born Recusant William Fitzsimon, and reburied under cover of darkness in consecrated ground at St. Kevin's Church, Camden Row, Dublin.

Exiled English Recusant poet Richard Verstegan wrote a detailed Renaissance Latin account of Archbishop O'Hurley's martyrdom in the volume Theatrum crudelitatum Hæreticorum nostri temporis ("Theatre of the Cruelties of the Heretics of our Time"), which was published at Antwerp, in the Spanish Netherlands in 1587.

Also following Catholic Emancipation in 1829, interest in Archbishop O'Hurley was rekindled by the republication of Bishop David Rothe's Analecta Sancta and Philip O'Sullivan Beare's Historiae Catholicae Iberniae Compendium.

[53] In the 12 February 1915 Apostolic decree In Hibernia, heroum nutrice, Pope Benedict XV formally authorized the introduction of Archbishop O'Hurley's Cause for Roman Catholic Sainthood.