Northern Ireland's most bitter political opponents bridged their divide last week and agreed to share power in a new Belfast government. Their agreement is a historic step toward peace for the long-divided province. Implementing the accord promises a "battle a day," but making the parties on either end of the political spectrum responsible will force them to govern together, rather than snipe at others.

The Good Friday peace process -- named after the day the agreement was reached in 1998 -- has been fitful, not least because of determined opposition by Mr. Ian Paisley and his Democratic Unionist Party (DUP). Mr. Paisley, a Protestant and staunch supporter of ties with Britain, considers Sinn Fein, the political wing of the Catholic Irish Republican Army (IRA), "evil" and has refused to deal with it until its leaders renounce their past and their IRA ties. Mr. Paisley and his supporters has dismissed assurances from those who argued that Sinn Fein had changed course and that the IRA had renounced armed struggle.

Mr. Paisley's opposition mattered -- not only because he is a populist firebrand, but also because the moderate parties that pushed compromise and backed the Good Friday accord have gradually lost power since it was agreed nine years ago. Public disillusionment with the peace process has grown since the Northern Ireland Assembly, a fruit of the agreement, was dissolved in 2002 amid allegations that an IRA spy ring operated out of it. That prompted the government of British Prime Minister Tony Blair to reinstall direct British rule. In the interim, steady hammering at the peace deal eroded the support of centrists, leaving Mr. Paisley's DUP the largest party when Northern Ireland's citizens went to the polls in 2003, and ever since.