Harris, Matthew (1825–90), revolutionary and agrarian radical, was born in Roscommon town, son of Peter Harris, a farmer from Athlone, Co. Westmeath, and his wife Ann Harris. After attending a hedge school, he worked for several years as a labourer in the building profession before establishing himself sometime during the 1850s as a building contractor in Ballinasloe, Co. Galway. An intelligent, eloquent, and essentially self-educated man, during the 1840s he had given strong vocal support to the repeal and Young Ireland movements and, by the 1860s, was well known in Galway as an ardent democrat and nationalist. As a result, in the wake of the abortive 1867 rising he was approached to join the IRB and assist in its reorganisation. He quickly became a leading figure in the movement, serving on its supreme council during the late 1860s, and helping to increase its ranks considerably in the Galway area. He viewed republicanism as synonymous with holding democratic and egalitarian sympathies. An ardent supporter of land redistribution, he was dissatisfied with the home rule movement of the 1870s, though he did support the radical John O'Connor Power (qv) in a May 1874 parliamentary by-election for Mayo.
During 1876 he established the Ballinasloe Tenants’ Defence Association to champion the grievances of poor tenant farmers (he would also form a Ballinasloe Workingmen's Club) and published a lengthy pamphlet, calling on the government to begin using the natural resources of the Shannon river to relieve distress in the west of Ireland. After the expulsion of Power and other home rulers from the IRB during 1876–7, Harris was reinstated on the supreme council as the representative of Connacht. In March 1877 he delivered a graveside oration during the burial of John O'Mahony (qv) in Glasnevin. He was prepared to support the ‘new departure’ programme of 1878–9 so long as it could be used to promote a radical land agitation in the west of Ireland that would challenge the property rights of the landed gentry and graziers. He spoke alongside James Daly (qv) and Power at the mass meeting in Irishtown, Co. Mayo (20 April 1879) and thereafter helped to found the Land League of Mayo (August 1879) and to rally the Connacht IRB to its side.
A member of the executive of the Irish National Land League (established October 1879), during its first year in existence he played a leading role in establishing branches of the league across the west of Ireland, emphasising its democratic ambitions on public platforms and dismissing the idea of his joining the parliamentary party of C. S. Parnell (qv) in Westminster. Once the underground republican movement began withdrawing active support for the Land League during the summer or autumn of 1880, he lost his position on the IRB supreme council to P. W. Nally (qv). In December 1880–January 1881 Harris was tried, along with thirteen other league leaders, for conspiracy to prevent the payment of rent, but the jury failed to reach a verdict. Unlike most league leaders, however, he appears not to have been imprisoned following Dublin Castle's suppression of the league in October 1881. He nevertheless remained committed to the league policy of promoting the interests of agricultural, as well as urban, workers and labourers, forming the short-lived Irish Labour and Industrial Union in August 1882 and, later, promoting the Trade and Labour Association.
Unlike Michael Davitt (qv) and Thomas Brennan (qv), Harris was willing to offer active support to the moderate Irish National League (established 10 October 1882), serving as a member of its executive. However, he generally used this position only to try to commit it to a programme of promoting radical land agitation. Overcoming his lifelong prejudice against Westminster politics, he accepted a Parnellite nomination during the crucial general election of 1885, and was elected MP for Galway East (1885–90). Rather than focusing on a parliamentary career, however, he became one of the principal supporters of the soon-to-be-outlawed Plan of Campaign agitation (from October 1886), calling for tenants to withhold rents on the Galway estates of Lord Dunsandle and the earl of Westmeath, and claiming that the ultimate aim of the agitation was nothing less than the complete abolition of landlordism. By 1887–8, however, severe ill health, brought about by stomach cancer, meant that he ceased to be politically active. He nevertheless maintained his radical reputation by arguing before the special commission of 1889 (which he could attend only in a wheelchair and with constant medical attention) that Irishmen had the right to seek complete political separation from Britain, and that any tenant-farmer had the right to use arms to resist an unjust eviction order. By the time he was charged with holding seditious views by the commission in November 1889, he was permanently bedridden at his home on Main St., Ballinasloe, where he died 14 April 1890. A son, Matthew, survived him and maintained the family business in Ballinasloe. His wife, Nora (née Bennett) had died several years previously. He was given a large public funeral in Ballinasloe, during which fellow agrarian-radical MPs carried his coffin and William O'Brien (qv) delivered a graveside oration.