Video: Troubles - Roving news report around Northern Ireland in 1972
On Sunday 30th January 1972 Catholic demonstrators in Londonderry clashed with British troops in a confrontation which left 13 of the demonstrators dead.
The troops claim they were responding to gunfire, but the Derry people claim they were fired on indiscriminately, in an unprovoked attack.
When British troops first arrived in Northern Ireland, little more than two years ago, they were greeted by the Catholics as protectors.
This report sets out the sequence of events from the 1968 Catholic-Protestant riots to the Derry shootings and burning of the British Embassy in Dublin which followed it.