During three decades of Troubles in Northern Ireland, there was bloodshed on both sides.
On Friday 21 July 1972, 19 Irish Republican Army (IRA) bombs exploded across Belfast in little over an hour, killing nine people and seriously injuring 130 others.
The bombing occurred just six months after the Bloody Sunday massacre of Catholics and civil rights protestors in Derry in 1972, after being fired on by British soldiers.
On Thursday 21 July, the Belfast city council will commemorate the 50th anniversary of the deadly urban attack which has become known as Bloody Friday.
Here’s everything you need to know.
What happened on Bloody Friday?
On Friday 21 July 1972, Belfast city centre was devastated by 22 bombs in the space of around 80 minutes.
The majority of the explosions were car bombs.
The blasts started at 2.10 pm that day at Smithfield - the city’s shopping district - and continued across Northern Ireland’s capital.
The main thoroughfares of York Street and Crumlin Road were targeted, as well as the railway station at Great Victoria Street.
Botanic Avenue, the Liverpool ferry terminus, Queen Elizabeth Bridge, an M2 bridge, a filling station and an electricity sub-station at Salisbury Avenue all were sites of blasts.
The Secretary of State for Northern Ireland at the time, William Whitelaw, told the House of Commons the bombings were “a wanton attack on innocent men, women and children”.
Who died during the Bloody Friday bombings?
Stephen Cooper (19), member of the British Army
William Crothers (15), civilian
John Gibson (45), civilian
William Irvine (18), civilian
Thomas Killops (39), civilian
Brigid Murray (65), civilian
Margaret O’Hare (34), civilian
Stephen Parker (14), civilian
Philip Price (27), member of the British Army
Who was responsible for the Bloody Friday attacks?
The IRA’s Belfast Brigade claimed responsibility for the bombings soon after the devastating Bloody Friday attacks.
But the group said it had given warnings to the security forces before the bombs exploded, informing the Public Protection Agency, the Samaritans and the press.
It had claimed the notice of at least 30 minutes before each explosion had given ample time for target areas to be cleared.
The IRA has accused the British of deliberately ignoring the warnings for “strategic policy reasons” - something denied by London’s security forces.
What happened next?
In the 10 days after Bloody Friday, 18 more people were killed in Belfast.
Then, at 4am on 31 July 1972 the Army launched Operation Motorman and moved in to clear “no go” areas set up by republican paramilitaries across Northern Ireland.
In Londonderry more than 1,000 soldiers in armoured vehicles moved into the Bogside and Creggan. In Belfast, the Army set up watchtowers in Casement Park in the west of the city.
In all, about 4,000 extra troops were brought into Northern Ireland during the operation. Two teenagers were shot and killed by the Army during the operation in Derry, and nine people were also killed that day in an IRA bomb in Claudy, County Londonderry.
In 2002, on the 30th anniversary of Bloody Friday, the IRA apologised to civilian victims of its campaign of violence.
In a statement in the republican newspaper An Phoblacht it said it offered “sincere apologies” to the families of those killed on Bloody Friday.