Byrne, Patrick (d. 1812), United Irishman or Defender, was the first of three sons of Henry Byrne (d. 1785), a wealthy merchant of Seatown, Dundalk, Co. Louth, and his wife, Mary, daughter of John Begg, a merchant in Bridge St., Dublin. The Byrnes were for several generations a prominent catholic family in Co. Louth and noted improvers. Henry's grandfather, Henry Byrne (1671–1761) of Allardstown, had five sons, all or most of whom became merchants. It was most likely Patrick Byrne who in September 1792 wrote the seditious pamphlet signed ‘Common sense’, attacking John Foster (qv), the leading landowner and politician in the county, the publication of which brought about the arrest of James Napper Tandy (qv) as well as Patrick Byrne himself. Convicted at the Dundalk assizes in April 1793 of circulating a seditious libel, Byrne was sentenced to two years’ imprisonment, a fine of £1,000 and securities of £2,000 to keep the peace for seven years. He underwent the sentence. Some years later he inherited a considerable property from his grand-uncle, Patrick Byrne of Castletown, who died unmarried in February 1796. His politics appeared to be unaffected, for on or about 5 June 1797 he attended a meeting of United Irish (and perhaps Defender) leaders at the Dublin lodgings of Bartholomew Teeling (qv). Also present were John Hughes (qv), Alexander Lowry (qv), William James MacNeven (qv), James Plunkett, Samuel Turner (qv), and Teeling himself. Like so many others, Byrne and his brother John fled from Ireland later that month. It is highly likely that Patrick and John Byrne were the two Irishmen named Byrne who on 15 October 1797 were reported by Theobald Wolfe Tone (qv) to be in prison at Liège, that they were ‘les frères Byrne’ said by him on 16 December to be coming shortly to Paris, and that one or the other was the Byrne said by Tone in June 1798 to be in Germany. There is little doubt that they were ‘the two Byrnes of Dundalk’ said by Samuel Turner, writing at the end of 1797 (or early in 1798), to be in Paris. From the records of the English College at Liège (suppressed in 1794), it is evident that they had been pupils there (Patrick 1784–8, John 1787–91), which may be a clue to how they came to be at Liège in 1797. Towards the end of 1798, Patrick was said by his mother (writing from Worcester) to have gone from Hanover to Töplitz Spa in Bohemia. Patrick Byrne died, unmarried, in 1812 in Berlin.
No less involved in the United Irish or Defender movement was his brother John Byrne (1776–1834), second son of Henry Byrne. Having spent some years at Lisburn, Co. Antrim, learning the linen trade, John Byrne returned to Co. Louth and built bleaching mills on the banks of the Dundalk river as well as the fine house that he called Union Lodge (as a mark of his democratic sentiments). He was a political associate of Teeling, whom he had got to know at Lisburn and who lodged with him, and of Anthony MacCann who in 1792 formed a Volunteer corps at Dundalk on the model of the Garde Nationale and later fled to France. In June 1797, just before John Byrne's flight, he and Teeling hosted a meeting of militants at Dundalk. It dispersed when word came of warrants for arrests; Byrne hid with Teeling, Turner, and Lowry in a barn. It appears Byrne, like his brother, made his way to the Continent. In 1798 Union Lodge was plundered and burnt down by loyalists. In January 1800, Teeling's brother Luke Teeling (qv) was reliably informed that Byrne had written from Prague that he had ‘got a commission in Prince Charles's army and was only waiting until his regimentals were made to join it’. This gives some credence to Burke's astonishing statement that Byrne eventually joined the British army, becoming an officer in the 15th Hussars and aide-de-camp to the duke of Cumberland, a royal duke famously antipathetic to catholics. John Byrne later lived at Worcester; he died at Bath in 1834, having married in 1815 Caroline Byrn (sic), daughter of a major in the service of the East India Company, and by her had a son and four daughters.
The youngest of the three Byrne brothers, Henry Byrne (1783–1830), was a lawyer who went to India, became chief justice of Ceylon (1818–20) and master of equity at Madras (1820–30). The exodus of the Byrnes is explained by William Brett, who knew Dundalk well: they ‘were all obliged to quit the country because they were suspected of being connected with the United Irishmen’. That they were able to do so and to prosper was most likely due to the influence of Foster, whose debts to the Byrne family reached £7,000.