Welsh Commanded the Second Battalion, Royal Green Jackets, on an eighteen-month tour of Northern Ireland in 1971 and 1972. He was in Derry on Bloody Sunday, as his Telegraph obituary noted:
- On January 30 1972, when the civil rights march at the centre of the ensuing controversy took place, he deployed only one company in Derry. Its task was to man a checkpoint known as Barrier 14 and prevent the protesters getting into the city centre. His other companies were held in reserve.
- That afternoon, Welsh was in a helicopter flying over the Bogside. His role was to observe what was happening on the ground, to inform Brigade HQ of the exact route of the march and to ascertain whether separation between the peaceful marchers and the rioters had occurred.
- The Inquiry into the events of that day, chaired by Lord Saville, was told that Welsh had expressed his misgivings to a senior officer that units of 1st Battalion the Parachute Regiment were to be deployed during the march, given their reputation for toughness.
- B1334 - Saville Inquiry witness statement, 3 August 2000, and atachments.
- Ts282, Saville Inquiry hearing transcript, 14 January 2003.
- Ts283, Saville Inquiry hearing transcript, 15 Jaunary 2003.
- Major-General Peter Welsh, telegraph.co.uk, 22 May 2011.