A small IRA battalion existed in Derry since the Troubles began , but it never had a steady number of volunteers until Bloody Sunday , which saw an influx of new recruits . The South Derry Battalion became the Derry Brigade ( sometimes referred to as the South Derry Brigade ) while also absorbing battalions based in northeastern County Donegal and northern County Londonderry
Bloody Sunday
Bloody Sunday (1972)
Provisional IRA Derry Brigade