Blennerhassett, Sir Rowland (1839–1909), 4th baronet, politician, and author, was born 5 September 1839 at Blennerville, Co. Kerry, the only son among two children of Sir Arthur Blennerhassett (1794–1849), 3rd baronet, a catholic landowner and high sheriff of Co. Kerry (1820), and Sarah Blennerhassett (née Mahony) (d. 1866). After her husband's death Sarah Blennerhasset married (16 May 1850) Frederick Randall of Highbury, Middlesex, England. Arthur's sister Rosanna (d. 1907) became a Red Cross sister and wrote an account of her work in South Africa, Adventures in Mashonaland (1893). Rowland was educated by the Benedictines at Downside and the Jesuits at Stonyhurst in England. He matriculated at Christ Church, Oxford, but because of his religion left without taking a degree and went to the University of Louvain, where he received a doctorate in political and administrative science. After studying at the universities of Munich (1864) and Berlin, he travelled throughout France and Germany, becoming acquainted with Bismarck and several leading French politicians, and formed a lifelong friendship with the liberal German catholic theologian, Johann Joseph Ignaz von Döllinger (1799–1890). He also became friends with John Henry Newman (qv) and the catholic historian Sir John (later Lord) Acton (1838–1902), liberal MP for Co. Carlow (1859–65), sympathising with Acton's opposition to ultramontanism. After the demise of Acton's Home and Foreign Review in December 1863, Blennerhassett helped found the Chronicle to replace it. It first appeared in March 1867 but failed within a year, its liberal catholicism and support for Irish home rule failing to find a sympathetic readership.
Through Döllinger he met his wife, Countess Charlotte von Leyden of Bavaria, one of the theologian's closest friends and most ardent disciples. Acton acted as intermediary between the couple and they were married 9 June 1870 in Munich by Döllinger; they had two sons and a daughter. The couple sympathised with the German old catholic movement which strongly resisted ultramontist reforms, but unlike most old catholics the Blennerhassets stayed within the Roman Catholic fold. With her husband's encouragement Charlotte became a successful professional author, writing a monumental three-volume biography of Mme de Staël.
Blennerhassett served as JP, deputy lieutenant of Co. Kerry, and high sheriff of Kerry (1866). He was liberal MP for Galway city (1865–74), and while standing for Galway in the 1868 general election readily accepted a pledge to vote for an amnesty for Fenian prisoners. After his liberal religious views lost him the support of catholic clergy in Galway, he stood as MP for Co. Kerry (1880–85). A lukewarm supporter of Isaac Butt (qv) and his home rule party, he was gradually alienated by militant Parnellism, seceding from the party in January 1881 and becoming an active member of the Irish Loyal and Patriotic Union (ILPU) founded in 1885 to oppose home rule. He contributed £70 to an ILPU fund to buy the notorious Pigott (qv) forgeries, used to link Parnell (qv) with the Phoenix Park murders. His estate in Kerry became heavily burdened with debt after his tenantry refused to pay their rents, and he spoke regularly in parliament on the Irish land question. In 1884 he advocated a sweeping measure of land purchase for tenant farmers; his proposal was published privately as Peasant proprietorship in Ireland (1884). He also contributed frequently to debates on education, and supported Gladstone's university bill of 1873. Regarded as a ‘Castle catholic’, he disapproved of William Walsh (qv) as candidate for archbishop of Dublin, considering him excessively nationalist, and wrote to the lord lieutenant, Earl Spencer (qv), on 1 March 1885, detailing ways to block the appointment. His parliamentary career ended with his defeat by the nationalist T. C. Harrington (qv) in Dublin's Harbour constituency (November 1885).
He continued to play a part in Irish public life and was appointed a commissioner of national education (1891), a senator of the Royal University of Ireland (1897), and a member of its standing committee, and an inspector of reformatory and industrial schools (1890–97). His ideas on education were greatly influenced by his admiration for German scientific and educational achievements. He became president of QCC (1897–1904), delivering an impressive inaugural address on university education, which was published in 1898. However, his attendance to his duties became uneven over the years and his presidency was not generally considered a success. Moreover, his efforts on behalf of British army recruitment made him unpopular with nationalist students. He was a visitor of QCC (1905–9), and was granted an LLD from the RUI. In 1905 he was appointed to the Irish privy council. A regular contributor of articles on continental politics and history to newspapers and journals, including The Times, the National Review, and the Deutsche Rundschau, he became a well-known commentator on foreign affairs. His early admiration for Germany gave way to an uneasiness about German hegemony, which (he warned) Britain might one day have to resist. An MRIA (1867), he published several of his parliamentary speeches, wrote the chapter ‘Ireland, 1837–87’ in Thomas Ward's The reign of Queen Victoria (1887), and edited Ringstoff's Bernstorff memoirs (1908). His family home was Churchtown, Killarney, Co. Kerry. He died 22 March 1909 at his town residence, 54 Rutland Gate, London, and was buried at Downside. He was succeeded by his eldest son, Sir Arthur Charles Francis Bernard Blennerhasset (1871–1915). Sir Rowland is sometimes confused with Rowland Ponsonby Blennerhassett (1850–1913), home rule MP for Co. Kerry (1872–85).