John Dillon, a Member of Parliament (MP) for over 35 years and the last leader of the Irish Parliamentary Party (IPP) in the struggle to secure Home Rule by parliamentary means, is born in Blackrock, Dublin on September 4, 1851. Through the 1880s he is perhaps the most important ally of the greatest 19th-century Irish nationalist, Charles Stewart Parnell, but, following Parnell’s involvement as co-respondent in a divorce case, he repudiates Parnell for reasons of political prudence.

Dillon is the son of the former “Young Irelander” John Blake Dillon (1814–1866). Following the premature death of both his parents, he is partly raised by his father’s niece, Anne Deane. He is educated at Catholic University School, at Trinity College, Dublin and at the Catholic University of Louvain in Belgium. He afterwards studies medicine at the Royal College of Surgeons in Dublin, then ceases active involvement in medicine after he joins Isaac Butt‘s Home Rule League in 1873

Dillon is a member of the British House of Commons during 1880–1883 and 1885–1918. For his vigorous work in the Irish National Land League, which seeks fixed tenure, fair rents, and free sale of Irish land, he is imprisoned twice between May 1881 and May 1882. He is Parnell’s fellow inmate in Kilmainham Gaol in Dublin from October 1881. For six months in 1888 he is imprisoned for aiding William O’Brien, author of the “plan of campaign” against high rent charges by English absentee landlords in Irish farming districts.

When Parnell is named co-respondent in Captain William Henry O’Shea’s divorce suit in 1890, Dillon and O’Brien at first affirm their support of him, but they finally decide that he will thenceforth be a liability as party leader. The party then splits, the anti-Parnellite majority forming the Irish National Federation, of which Dillon serves as chairman from 1896. In 1900, however, he agrees to join a reunited party under the Parnellite John Redmond.

During the prime ministry of Arthur James Balfour (1902–1905), Dillon comes to believe that the British Conservative government intends to grant Irish reforms without independence, thereby “killing Home Rule by kindness.” In 1905 he advises Irishmen to vote for Liberal Party candidates for Parliament, and, after the Liberals had taken office that year, he supports their reform program.

Throughout World War I Dillon vehemently opposes the extension of British military conscription to Ireland, both because that measure would strengthen the agitation by the more extreme nationalist Sinn Féin party and because he never accepted the view that British imperial interests necessarily coincided with those of Ireland. After the Easter Rising in Dublin in 1916, he protests against the harsh measures that ensue and, in the House of Commons, makes a passionate speech in defense of the Irish rebels.

Upon Redmond’s death on March 6, 1918, Dillon, who had broken with him over Irish support for the British war effort, succeeds him as Irish Parliamentary Party leader. By that time, however, the party has been discredited and in the 1918 Irish general election Sinn Féin wins easily. On losing his House of Commons seat to Éamon de Valera, the future president of the Republic of Ireland, he retires from politics.

Dillon dies in a London nursing home at the age of 76, on August 4, 1927. He is buried four days later in Glasnevin Cemetery in Dublin. There is a street named after him in Dublin’s Liberties area, beside the old Iveagh Markets. One of his six children is James Mathew Dillon (1902–1986), a prominent Irish politician and leader of the National Centre Party and of Fine Gael (1957–1966) and also serves as Minister for Agriculture (1954-1957).