O'Brien, William Smith (1803–64). Smith O'Brien was an unlikely, unwilling, and unsuccessful Irish rebel. The younger son of a protestant baronet from Co. Clare, with family links to the earls of Thomond, he was educated at Harrow and Trinity College, Cambridge. He served in Parliament 1828–31 and from 1835 when he was returned for Co. Limerick. He moved steadily into a nationalist stance, much influenced by Young Ireland, and in 1843 declared for repeal of the Union. He also moved from advocating peaceful agitation to toying with armed protest. In May 1848 he was prosecuted in Dublin for an inflammatory speech but no verdict was returned. A rising planned for August dwindled into a farcical riot at Ballingarry, Co. Tipperary, where O'Brien explained that he had no food to give his followers and did not intend any violence to property. An attack upon 46 policemen, holed up in Widow McCormack's cottage, was unsuccessful. O'Brien was sentenced to death, but pardoned against his will and transported. After six years in Tasmania he was released but took no further part in politics. He himself described the rising of 1848 as an ‘escapade’.

J. A. Cannon

O'Brien, William Smith (1803–64) Irish nationalist leader. He entered Parliament as an Irish member in 1828, and supported Roman Catholic emancipation. In 1843, he joined Daniel O'Connell's Repeal Association against the Act of Union (1800), but left in 1846 to set up the more militant Repeal League. Arrested after leading an ineffective insurrection in 1848, O'Brien was sentenced to death, later commuted to transportation.