Mallon, John (1839–1915), policeman, was born 10 May 1839 near Meigh, Co. Armagh, the eldest child of Thomas Mallon, a tenant farmer, and his wife, Judith (Susan) Connolly. Educated at Newry model school and mentored by Canon Michael Murphy, Mallon was then apprenticed to a Newry draper's firm. In 1858 he travelled to Dublin with the possible intention of enrolling in the Royal Engineers, but instead, on 1 December, he joined the Dublin Metropolitan Police (DMP) with the rank of constable (warrant number 5830). A protégé of DMP commissioner Colonel Henry Lake (1808–81), Mallon was assigned desk jobs successively in F, B, and F divisions before, on 7 March 1862, being transferred to the detective G division under Superintendent Daniel Ryan, who increasingly came to rely on the young detective to run the DMP's informer network.
In 1867 Mallon was appointed acting inspector, then two years later inspector, and in 1874 he succeeded Ryan as superintendent over the heads of some of his more senior colleagues. By then Mallon was well conversant with the Irish physical force movement and was invariably asked to handle political matters. The most dramatic of these came on 13 October 1881, when the Dublin castle authorities chose him for the delicate task of arresting Charles Stewart Parnell (qv), an incident that reflected better on Mallon than it did on Parnell.
Mallon made his name as ‘the Irish Sherlock Holmes’ over his tracking down and successfully bringing to book Invincibles such as Joe Brady (qv) and Tim Kelly (qv) who were directly involved in the Phoenix Park murders of 6 May 1882. This was done by his tricking one of the leading conspirators, James Carey (qv), into turning informer on his associates. It was at this difficult time that the lord lieutenant, Earl Spencer (qv), wrote, ‘we depend in Dublin on one man, Mallon; were he to die or be killed, we have no one worth a row of pins’.
For the next twenty years Mallon was the undisputed authority on revolutionary movements in Ireland, and as such worked with the newly established Special Irish Branch in Britain. In 1883 he was promoted to chief superintendent, in an effort by the authorities to restore morale, which was then low in the DMP. By 1892 Mallon could boast that he knew of fifty active IRB men in Dublin and could ‘put his finger’ on every one of them. On 28 January 1893 he was appointed assistant commissioner, the first catholic to achieve such a senior position in the force. With the newly appointed DMP chief commissioner, John Joseph Casimir Jones (1839–1929) and Under-Secretary David Harrel (qv), a formidable team was created, which in no small part reduced the effectiveness of the physical force men in Dublin in the mid 1890s. When incidents did occur, such as the explosions at the detective office in Exchange Court in 1892 and at the Four Courts in 1893, these were investigated by Mallon, whom the authorities insisted must move his home from the South Circular Road to accommodation in Dublin castle, where he could be available at all times. The late 1890s brought great strain on Mallon, with the ’98 centenary and then in 1899 the eruption of street violence at the outbreak of the South African war.
Mallon married Elizabeth Byrne, daughter of John Byrne, a Dublin greengrocer, on 8 January 1866. They had twelve children, four of whom survived into adulthood: Stephen, Mary, Thomas and John. In 1902 he retired and returned to Meigh with his family, serving as a magistrate there. He retained an interest in public affairs and through the vehicle of the journalist Frederick Bussy largely dictated a biography, which was published in 1910. Mallon died 9 October 1915 after attending mass in Meigh and is buried in the old Killevy cemetery. He left an estate valued at £2,900.