Sunday 30 January 1972 was one of the most deadly – and consequential – days during three decades of conflict in Northern Ireland. In the streets where it happened – the images of Bloody Sunday are painted on the walls and seared in people's minds. A civil rights march was held on a wintry, sunny afternoon in Londonderry.

The British Army regularly crossed the Border illegally throughout the Troubles, including eight British SAS soldiers who were arrested by the Gardaí and Irish Army at Flagstaff in County Louth in May 1976.

A former senior Nato commander and naval expert has told Westminster politicians that a united Ireland would pose a strategic threat. The loss of the protection afforded by the North would deepen the threat to Britain from Russia and China, Rear Admiral Chris Parry told MPs and members of the House of Lords in a briefing on Wednesday.

Only 7% of LAist readers currently donate to fund our journalism. Help raise that number, so our nonprofit newsroom stays strong in the face of federal cuts. Donate now. At midnight last night, the British army's operation in Northern Ireland came to an end.