The Provisional Irish Republican Army fail to assassinate Prime Minister Margaret Thatcher and her cabinet. The bomb kills five people and wounds at least 31 others.

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.

On 12 October 1984 the Provisional Irish Republican Army (IRA) attempted to assassinate members of the British government, including the prime minister, Margaret Thatcher, at the Grand Hotel in Brighton, England. Five people were killed, including the Conservative MP Sir Anthony Berry; more than thirty people were injured. Thatcher was uninjured. The bombing was a key moment in the Troubles, the conflict in Northern Ireland between unionists and republicans over the constitutional position of Northern Ireland, which took place between the late 1960s and 1998.

Margaret Hilda Thatcher, Baroness Thatcher, was a British stateswoman who served as Prime Minister of the United Kingdom from 1979 to 1990 and Leader of the Conservative Party from 1975 to 1990. She was the longest-serving British prime minister of the 20th century and the first woman to hold the position. As prime minister, she implemented policies that came to be known as Thatcherism. A Soviet journalist dubbed her the "Iron Lady", a nickname that became associated with her uncompromising politics and leadership style.