Power, John O'Connor (1846–1919), politician, was born near Ballinasloe, Co. Galway. In later life, on enrolling to study law, he claimed to be the third son of a gentleman farmer named Patrick Power, but other evidence suggests that he was the illegitimate son of a policeman named Fleming. Initially sent to a workhouse (where he contracted smallpox, which left permanent marks on his face), at the age of 15 he was sent to work with relatives in the house-painting trade in Rochdale, Lancashire, where he probably attended school. He grew into a medium-sized and heavily built young man. Around 1866 he met Michael Davitt (qv) and was sworn into the IRB. He was privy to the abortive plot to raid Chester Castle (11 February 1867) and, allegedly, played a part in directing the rescue of two IRB leaders in Manchester (18 September 1867), the event that resulted in the execution of the ‘Manchester martyrs’. It is clear, however, that he did not become significant in revolutionary circles until that winter, when he was delegated by the Manchester IRB to go to America and confer with W. R. Roberts (qv), who favoured reorganising the IRB under a supreme council. In January 1868 he arrived in Dublin to implement Roberts's plan, but was soon arrested (17 February) and imprisoned without trial in Kilmainham jail. On being released in mid July, he moved to Galway, serving for a time as the representative of Connacht on the IRB's new supreme council. He assisted in arms distribution but, probably through the influence of G. H. Moore (qv), became more interested in parliamentary politics.
This shift strengthened after he enrolled (January 1871) in St Jarlath's College, Tuam, with the patronage of some Galway clergymen. He taught history during his final year (1873–4) at St Jarlath's and, through speaking at meetings of the Home Rule Confederation of Great Britain, acquired the reputation of a great platform orator. Together with Patrick Egan (qv), he favoured using the influence of the IRB and Irish radicals in Britain to remould the conservative home rule movement in Ireland along more radical lines. He was a leading speaker at the inaugural convention of the Home Rule League in Dublin (18–21 November 1873), but controversy emerged in republican circles after he stood successfully for a parliamentary by-election for Mayo county (May 1874). The first non-landowner ever to be returned for the county, he became a pioneer of obstructionist tactics in parliament and went on two lengthy fund-raising lecture tours for the Home Rule League in America (August 1875–February 1876, October 1876–February 1877), though these were generally unsuccessful. As he was a divisive figure, the IRB voted in August 1876 to expel him from its ranks (formally in March 1877). Davitt, however, retained a respect for him, on account of his amnesty work.
Admitted to the Middle Temple in London on 14 February 1878, he was called to the bar on 17 November 1881. Power was then considered by many as a potential leader of the Home Rule League, being perhaps its finest orator. This made him a serious rival to C. S. Parnell (qv), the leader of the Home Rule Confederation of Great Britain, who had accompanied Power during his 1876 US tour. Although a leading speaker at the Irishtown meeting (20 April 1879) and a member of the committee of the Irish National Land League, Power was soon marginalised by Davitt, who knew he would alienate IRB and Irish-American support, and also by Parnell. In April 1880 both Parnell and Power were returned for Co. Mayo, Power topping the poll. This ensured that no liberal candidate was returned, although it was widely believed that Parnell's only purpose in running for Mayo (he was also elected for Cork and Meath) was simply to remove Power from the political stage. In turn, Power was absent from a meeting where Parnell was elected chairman of the Home Rule League (17 May 1880). Having been excluded from the new ‘Irish parliamentary party’, Power now abandoned obstructionist tactics and alienated the Land League by supporting Gladstone's land bill of April 1881. He soon married a wealthy English widow (name unknown) and became an active member of the National Liberal Club in London.
In 1885 he did not attempt to defend his Mayo seat but instead accepted an invitation to run as a liberal candidate for the Kennington constituency in London, polling well but failing to win the seat. He put himself forward in 1892 as an independent candidate for Mayo West, but was heavily defeated. He never returned to Ireland, his political career effectively ending in 1895 when he ran as the liberal candidate for Bristol South, polling well but again failing to win a seat. An occasional contributor to monthly review magazines in Britain, in later years he also wrote a book, The making of an orator (1906). His later years were spent in relative obscurity, mostly working as a barrister. He died in London 21 February 1919 at his home, 7 Luttrell Avenue, Putney. Reputedly, his papers were used for a history of the home rule movement that was published the following year, although these do not appear to have survived.