However, what was new was the use of the Parachute Regiment for patrols in parts of Derry which had previously been subject to an unofficial demarcation between British and IRA territory. The march took place amid widespread resentment at Internment, introduced the previous year. At 2pm the crowds began to gather in Creggan and moved off towards the centre of Londonderry, reaching a strength of about 25,000 people. The next critical event took place just before 4pm as marchers turned down William Street to face an army barricade blocking their way to the city centre. At that moment, a high-velocity shot struck a Church on the roof of which were solders from 1 Para's mortar platoon.
Confusion reigns over the origin of that shot.
The Parachute Regiment soldiers, who believed the shot came from the Glenfada Park area, began firing their first rounds, wounding two men. As rioting became widespread, the Parachute Regiment was given the order at 4.07pm to pick up rioters as the army pressed on with its principal task of confining the march within the Bogside area. Accounts of the critical moments are necessarily poles apart. A mortar platoon sergeant said he saw and fired at three armed men. However, Dr Edward Daly - who was later to become Bishop of Derry, said he did not believe the Paras were being fired on.