Bloody Sunday 1972: The day's events explained

Bloody Sunday has become synonymous with the darkest period of the Troubles in Northern Ireland. But how did a protest march on January 30th 1972 lead to a massacre? Thirteen people were killed and a further 15 wounded after members of the Army's Parachute Regiment opened fire on civil rights demonstrators in the Bogside - a predominantly Catholic part of Londonderry (Derry). The image of a Catholic priest waving a blood-stained handkerchief as he helped a victim to safety was broadcast around the world.