William Smith O'Brien (born Dromoland , Ireland, October 17 1803; died Bangor, Wales, June 18 1864) was an Irish Nationalist and MP and leader of the Young Ireland movement.

The son of politician Lucas O'Brien, he took the additional surname Smith, his mother's maiden name, upon inheriting property through her. Educated at Harrow School and Trinity College, Cambridge, in 1825 he became Conservative MP for Ennis, moving to become MP for County Limerick in 1835, holding his seat in the House of Commons until 1848.

Although a Protestant, he supported Catholic emancipation but remained a supporter of British-Irish union. However, in 1843, in protest against the imprisonment of Daniel O'Connell, he joined O'Connell's anti-union Repeal Association . Three years later, disillusioned by O'Connell's unwillingness to support violent protest, O'Brien withdrew the Young Irelanders from the association, and in January 1847 founded the Irish Confederation to campaign for additional famine relief. In March 1848 he spoke out in favour of a National Guard and tried to incite a national rebellion. After being unsuccessfully tried for sedition, on July 29 1848, he led peasants in a futile, almost bloodless battle against police at Ballingarry, County Tipperary. The jury found him guilty of high treason and he was sentenced to death, but this was commuted to transportation for life to Van Diemen's Land (Tasmania).

O'Brien attempted to escape from Maria Island off Tasmania, but was betrayed by a certain Ellis, captain of the schooner hired for the escape, and sent to Port Arhur where he met up with John Mitchel. The cottages O'Brien lived in on Maria Island and Port Arthur remain as they were then to this day. Ellis was tried for this betrayal by Terence MacManus at a lynch court in San Francisco, but freed for lack of evidence.

In 1854, after five years in Tasmania, he was released on the condition he never return to Ireland, and settled in Brussels. In May 1856 he was granted an unconditional pardon and returned to Ireland in July, but played no further part in politics.

There is a statue of him on O'Connell Street, Dublin.

Quotes

"The new Irish flag would be Orange and Green, and would be known as the Irish tricolour."