Question: When was the bombing for which The Balmoral Furniture Company bombing was thought to be a retaliation for?

full_context: Document 1: The Troubles in Limavady: Four people were killed in violence relating to the Northern Ireland Troubles in the town of Limavady, County Londonderry. All were Protestants, and all were killed by the Provisional Irish Republican Army (PIRA, better known as the IRA). One was a prison officer and one was a Royal Ulster Constabulary (RUC) officer. The other two victims were civilians killed by a van bomb explosion outside the Limavady RUC base on 28 March 1972. They were driving past at the time of the attack.
Document 2: Omagh bombing: The Omagh bombing was a car bombing that took place on 15 August 1998 in Omagh, County Tyrone, Northern Ireland. It was carried out by a group calling themselves the Real Irish Republican Army, a Provisional Irish Republican Army (IRA) splinter group who opposed the IRA's ceasefire and the Good Friday Agreement. The bombing killed 29 people (including a woman pregnant with twins) as well as injuring some 220 others, a death toll even higher than that of any single incident during what were considered 'the Troubles' (1968-10 April 1998). Telephoned warnings had been sent about 40 minutes beforehand, but were claimed to be inaccurate and police had inadvertently moved people towards the bomb.
Document 3: Donnelly's Bar and Kay's Tavern attacks: On 19 December 1975, two coordinated attacks were carried out by the Ulster Volunteer Force (UVF) in pubs either side of the Irish border. The first attack, a car bombing took place outside Kay's Tavern, a pub in Dundalk in the Republic of Ireland close to the border. The second attack, a gun and bomb attack, took place at Donnelly's Bar & Filling Station in Silverbridge, County Armagh just across the border inside Northern Ireland. The attack has been linked to the Glenanne gang, a group of Loyalist militants who were either members of the UVF, the Ulster Defence Regiment (UDR), the Royal Ulster Constabulary (RUC) and the closely linked UVF paramilitary the Red Hand Commando (RHC), some of the Glenanne gang were members of the two of these organizations at the same time like gang leaders Billy Hanna who was in both the UVF and the UDR and who fought for the British Army during the Korean War and John Weir (loyalist) who was in the UVF and was a Sergeant in the RUC. At least 25 British soldiers and police officers were named as members of the gang.
Document 4: Bloody Sunday (1921): Bloody Sunday or Belfast's Bloody Sunday was a day of violence in Belfast, Ireland (present-day Northern Ireland) on 10 July 1921, during the Irish War of Independence. In retaliation for an Irish Republican Army (IRA) ambush of a police raiding party, Protestant loyalists attacked Catholic enclaves, burning homes and businesses. This sparked gun battles between republican and loyalist paramilitaries, and street fighting between Catholics and Protestants. There was also shooting between republicans and police, and it is claimed that some police patrols fired indiscriminately at Catholic civilians. Seventeen people were killed on 10 July, and a further eleven were killed or fatally wounded over the following week. At least 100 people were injured. About 200 houses were badly damaged or destroyed, leaving 1,000 people homeless. The violence took place just before a truce came into effect, which ended the war in most of Ireland.
Document 5: Thiepval barracks bombing: The Thiepval Barracks bombing was a double car bomb attack carried out by the Provisional Irish Republican Army (IRA) on 7 October 1996. The bombs exploded inside Thiepval Barracks, the British Army headquarters in Northern Ireland. One British soldier was killed and 31 people were injured. This bombing was the first major attack on a military base in Northern Ireland since the ending of the IRA's ceasefire on 9 February 1996, when it exploded a large bomb in London's Docklands.
Document 6: Greysteel massacre: The Greysteel massacre was a mass shooting that happened on the evening of 30 October 1993 in Greysteel, County Londonderry, Northern Ireland. Three members of the Ulster Defence Association (UDA), a loyalist paramilitary group, opened fire in a crowded pub during a Halloween party, killing eight civilians and wounding thirteen. The pub was in an Irish Catholic and Irish nationalist area. The group claimed responsibility using their cover name "Ulster Freedom Fighters" and said that the attack was revenge for the Shankill Road bombing by the Provisional IRA a week earlier.
Document 7: 1994 Shankill Road killings: The 1994 Shankill Road killings took place on 16 June 1994. The Irish National Liberation Army (INLA) shot dead three Ulster Volunteer Force (UVF) members – high-ranking member Trevor King, Colin Craig and David Hamilton – on the Shankill Road in Belfast, close to the UVF HQ.The following day, the UVF launched two 'retaliatory' attacks. In the first, UVF members shot dead a Catholic civilian taxi driver in Carrickfergus. In the second, they shot dead two Protestant civilians in Newtownabbey, whom they believed were Catholics. The Loughinisland massacre, two days later, is believed to have been a further retaliation.
Document 8: 1973 Old Bailey bombing: The 1973 Old Bailey bombing was a car bomb attack carried out by the Provisional IRA (PIRA) which took place outside the Old Bailey Courthouse on 8 March 1973. The attack was carried out by a 10-person ASU from the Provisional IRA Belfast Brigade. The unit also exploded a second bomb which went off outside the Ministry of Agriculture in London on the same day at around the same time the bomb at the Old Bailey bomb went off. This was the Provisional IRA's first major attack on mainland Britain since The Troubles began back in 1969. One British civilian died of a heart attack attributed to the bombing, estimates of the injured range from 180 - 220. Two additional bombs were found and defused. Nine people from Belfast were convicted six months later for the bombing, and one acquitted for providing information to the police.
Document 9: Ballygawley bus bombing: The Ballygawley bus bombing was a roadside bomb attack by the Provisional Irish Republican Army (IRA) on a bus carrying British soldiers in Northern Ireland. It occurred in the early hours of 20 August 1988 in the townland of Curr near Ballygawley, County Tyrone. The attack killed eight soldiers and wounded another 28. It was the second-deadliest attack on the British Army in Northern Ireland during the Troubles, after the Warrenpoint ambush of 1979. In the wake of the bombing the British Army began ferrying its troops in and out of County Tyrone by helicopter.
Document 10: Blast bomb: Blast bomb is a term used in Northern Ireland for a type of improvised explosive device. More specifically, these devices are usually a form of homemade grenade, which is thrown at a target. These devices have been used in a number of public order situations, and in attacks on the Royal Ulster Constabulary, its successor Police Service of Northern Ireland (PSNI) and British Army. A police officer was killed by a blast bomb in Northern Ireland during The Troubles by loyalists and in 2001 Loyalist protesters threw a blast bomb at Catholic schoolgirls, some as young as 4 years old, making their way to school in September 2001. Ordinary fireworks are sometimes used in a similar fashion to blast bombs. Such devices which are packed with nails are referred to as nail bombs.
Document 11: The Troubles in Magherafelt: A total of eleven people were killed in violence relating to the Northern Irish Troubles in the town of Magherafelt, County Londonderry. Nine were killed by the Irish Republican Army (IRA), including three IRA members killed by the premature explosion of their own bomb while travelling through Magherafelt. One was killed by a non-specific republican group and another by the opposing Ulster Freedom Fighters (UFF). Of the others killed by the IRA, four were Protestant civilians. Three of them were killed in two separate car bomb explosions. The fourth Protestant civilian was shot because his firm was a contractor for the British Army and the Royal Ulster Constabulary (RUC). The IRA's other two victims were both Protestant members of the security forces, one from the RUC and the other from the Ulster Defence Regiment. Both were off duty when killed. The man killed by the UFF was a Sinn Féin councillor who was shot in his workplace. The man killed by the non-specific republican group was a Catholic civilian.
Document 12: McGurk's Bar bombing: On 4 December 1971, the Ulster Volunteer Force (UVF), an Ulster loyalist paramilitary group, detonated a bomb at McGurk's Bar in Belfast, Northern Ireland. The pub was frequented by Irish Catholics/nationalists. The explosion caused the building to collapse, killing fifteen Catholic civilians—including two children—and wounding seventeen more. It was the deadliest attack in Belfast during the Troubles.
Document 13: Oxford Street bombing: On the 19 December 1974 the Provisional IRA exploded a car bomb which was parked opposite to Selfridge's department store on Oxford Street in London. The bomb attack was carried out by an IRA active service unit (ASU) known as the Balcombe Street Gang who carried out some 40 attacks in England between October 1974 - December 1975.
Document 14: 1971 Balmoral Furniture Company bombing: The Balmoral Furniture Company bombing was a paramilitary attack that took place on 11 December 1971 in Belfast, Northern Ireland. A bomb exploded without warning outside a furniture showroom on the Shankill Road in a predominantly unionist area, killing four civilians, two of them babies. It is widely believed that the bombing was carried out by members of the Provisional Irish Republican Army (IRA) in retaliation for the bombing of McGurk's pub a week earlier, which killed 15 Catholic civilians. The Ulster Volunteer Force (UVF) had carried out that bombing.
Document 15: Shankill Butchers: The Shankill Butchers was an Ulster loyalist gang—many of whom were members of the Ulster Volunteer Force (UVF)—that was active between 1975 and 1982 in Belfast, Northern Ireland. It was based in the Shankill area and was responsible for the deaths of at least 23 people, most of whom were killed in sectarian attacks. The gang was notorious for kidnapping and murdering random Catholic and suspected Catholic civilians; each was beaten ferociously and had his throat hacked with a butcher's knife. Some were also tortured and attacked with a hatchet. The gang also killed six Ulster Protestants over personal disputes, and two other Protestants mistaken for Catholics. Most of the gang were eventually caught and, in February 1979, received the longest combined prison sentences in United Kingdom legal history. However, gang leader Lenny Murphy and his two chief "lieutenants" escaped prosecution. Murphy was killed in November 1982 by the Provisional IRA, likely acting with loyalist paramilitaries who perceived him as a threat. The Butchers brought a new level of paramilitary violence to a country already hardened by death and destruction. The judge who oversaw the 1979 trial described their crimes as "a lasting monument to blind sectarian bigotry".
ground_truth: 4 December 1971