The Troubles: The Provisional Irish Republican Army detonated twenty-two bombs throughout Belfast, Northern Ireland.

The Troubles were an ethno-nationalist conflict in Northern Ireland that lasted for about 30 years from the late 1960s to 1998. Also known internationally as the Northern Ireland conflict, it began in the late 1960s and is usually deemed to have ended with the Good Friday Agreement of 1998. Although the Troubles mostly took place in Northern Ireland, at times violence spilled over into parts of the Republic of Ireland, England, and mainland Europe.

The Provisional Irish Republican Army, officially known as the Irish Republican Army and informally known as the Provos, was an Irish republican paramilitary force that sought to end British rule in Northern Ireland, facilitate Irish reunification and bring about an independent republic encompassing all of Ireland. It was the most active republican paramilitary group during the Troubles. It argued that the all-island Irish Republic continued to exist, and it saw itself as that state's army, the sole legitimate successor to the original IRA from the Irish War of Independence. It was designated a terrorist organisation in the United Kingdom and an unlawful organisation in the Republic of Ireland, both of whose authority it rejected.

Bloody Friday is the name given to the bombings by the Provisional Irish Republican Army (IRA) in Belfast, Northern Ireland on 21 July 1972, during the Troubles. At least twenty bombs exploded in the space of eighty minutes, most within a half-hour period. Most of them were car bombs and most targeted infrastructure, especially the transport network. Nine people were killed: five civilians, two British soldiers, a Royal Ulster Constabulary (RUC) reservist, and an Ulster Defence Association (UDA) member, while 130 were injured. The IRA said it sent telephoned warnings at least thirty minutes before each explosion and said that the security forces wilfully ignored some of the warnings for their own ends. The security forces said that was not the case and said they were overstretched by the sheer number of bombs and bomb warnings, some of which were hoaxes.