This chapter explores the intelligence war’s impact on the IRA in its urban heartlands of Belfast and Derry City between 1976 and 1998. In Belfast, there was a decline in IRA attacks during this period, partly as a result of infiltration and surveillance. Nonetheless, I argue that there was also a decline in IRA attacks, primarily because of the need to avoid civilian casualties occurring on a regular basis, in order to sustain Sinn Féin’s vote. By the 1990s, the Belfast Brigade had recommenced a commercial bombing campaign that would cause extensive financial damage and necessitate the continuation of security installations and patrols. In Derry City, the IRA’s campaign was more of a persistent nuisance by 1994. But this decline was not because of the intelligence war. Rather, it was largely that the SDLP had begun rebuilding the city for nationalists. The IRA risked a decline in electoral support if they attacked the city infrastructure again. The evidence provided does not suggest that the Belfast and Derry City IRA Brigades called a prolonged ceasefire in August 1994 primarily because of the intelligence war. Chapter 8 also debates the impact of suspected agents and informers on the Belfast and Derry City IRA, including the Stakeknife and Raymond Gilmour cases.