Following the unsuccessful talks , Mac Stíofáin ordered an intensification of the IRA campaign which peaked on 21 July 1972 , or Bloody Friday , when the IRA detonated 22 car bombs in less than two hours across Belfast , killing nine people and injuring 130 . In his memoirs , Mac Stíofáin described the operation as " a concerted sabotage offensive " intended to demonstrate the IRA was capable of planting a large number of bombs at once
Bloody Friday
Bloody Friday (1972)
Seán Mac Stíofáin