Rooted in its campaign for a united Ireland, Sinn Fein was long an outsider in politics due to its links with the Irish Republican Army. With the conflict in Northern Ireland largely over since a 1998 peace deal, the movement has reinvented itself to appeal to a new generation of voters. Now, in a historic shift, it has become the biggest party in the north and also leads opinion polls in the Irish Republic to the south. That makes its demand for a referendum on unification harder to ignore. The party, whose name means “Ourselves Alone,” was created amid the campaign for Irish home rule at the start of the 20th century. After the Catholic south won its independence from Britain in 1921, Sinn Fein split, ultimately creating what are now the three largest parties in the Republic.