And on May 8, 2007, a day many thought would never come, the Rev. Ian Paisley, who had founded the Democratic Unionist Party and had long stood for continued Ulster association with Britain, and Mr. McGuinness, who had fought for Ulster’s incorporation into a united Ireland, took oaths as the leader and deputy leader, respectively, of Northern Ireland’s power-sharing government.
As Prime Ministers Tony Blair of Britain and Bertie Ahern of Ireland looked on, the proceedings ended direct British control of Northern Ireland and reinstated home rule for its 1.8 million people. Legislative power was vested in a Northern Ireland Assembly, and Ulster began a new era in which long-bitter adversaries pledged to abandon armed struggles and embrace political solutions.
The I.R.A. had already destroyed its weapons and given up its clandestine cells, and Sinn Fein (pronounced shin-FAIN) had endorsed a reconstituted Ulster police force, which it had regarded for decades as an arm of British and Protestant repression.
Left unresolved was whether Northern Ireland would ever be reunited with the predominantly Catholic Irish Republic. The Good Friday Agreement provided that that could happen only with the consent of Northern Ireland, and it made it likely that Ulster and its Protestant majority would remain in perpetuity — along with the legacies of killings and religious enmities.
Once banned from entering Britain, Mr. McGuinness won a seat in the House of Commons in London; ran unsuccessfully for the presidency of Ireland in 2011; visited prime ministers several times at 10 Downing Street; met Presidents Bill Clinton, George W. Bush and Barack Obama at the White House; and shook hands twice with Queen Elizabeth II.
“This is the side of his political life that McGuinness wants the Irish people to remember: the reformed man, the young, hotheaded idealist who learned the error of his ways and forged peace, an achievement that still wins him plaudits from around the world,” the British magazine New Statesman said in 2011. “To some in Ireland he is a hero — a man who stood up for the oppressed, who fought the British. To others, he was, is and will always be a criminal.”
James Martin Pacelli McGuinness was born in Derry, Northern Ireland, on May 23, 1950, one of seven children of William and Peggy McGuinness, a Catholic family that shared two bedrooms and an outdoor toilet in the crowded slum of Bogside, a setting for much violence during the Troubles. His father worked in an iron foundry, and his mother in a shirt factory. The parents attended Mass and took communion daily, and they gathered their six sons and daughter nightly for a recitation of the rosary.
Martin was a bright, eager boy who loved the poems of W. B. Yeats and played chess, but he failed the 11 Plus exams in his last year in grade school. So instead of getting an academic education, he went to a Christian Brothers technical school, where the boys were beaten. He quit school at 15 and became a butcher’s assistant. Like many Bogside youths, he joined the lionized I.R.A. and was a gunman at 18.
In the late 1960s and early ’70s, Bogside was a war zone of hatred and revenge. Stone-throwing youths were beaten by the Royal Ulster Constabulary. There were riots and protests. Two boys were shot dead by British soldiers in 1971. The Provisional I.R.A., the more militant successor to the I.R.A., launched ferocious counterattacks. Arson fires burned 100 shops, and snipers killed 26 British soldiers in Derry alone in 1971 and ’72.
Mr. McGuinness was second in command of the Derry I.R.A. on Bloody Sunday, the grim day in 1972 when British troops fired on unarmed civilians staging a peaceful protest against the British practice of internment without trials. Fourteen people were killed in what became known as the Bogside Massacre.
In 1973 and 1974, Mr. McGuinness was imprisoned twice, for possession of a car filled with explosives and ammunition, and for his acknowledged membership in the illegal I.R.A.