Falklands War: The Royal Navy destroyer HMS Cardiff engaged and destroyed a British Army helicopter in a friendly-fire incident.

The Falklands War was a ten-week undeclared war between Argentina and the United Kingdom in 1982 over two British dependent territories in the South Atlantic: the Falkland Islands and its territorial dependency, South Georgia and the South Sandwich Islands. The conflict began on 2 April 1982, when Argentina invaded and occupied the Falkland Islands, followed by the invasion of South Georgia the next day. On 5 April, the British government dispatched a naval task force to engage the Argentine Navy and Air Force before making an amphibious assault on the islands. The conflict lasted 74 days and ended with an Argentine surrender on 14 June, returning the islands to British control. In total, 649 Argentine military personnel, 255 British military personnel, and three Falkland Islanders were killed during the hostilities.

The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against France. The modern Royal Navy traces its origins to the English Navy of the early 16th century; the oldest of the UK's armed services, it is consequently known as the Senior Service.

HMS Cardiff was a British Type 42 destroyer and the third ship of the Royal Navy to be named in honour of the Welsh capital city of Cardiff.

On 6 June 1982, during the Falklands War, the British Royal Navy Type 42 destroyer HMS Cardiff engaged and destroyed a British Army Westland Gazelle helicopter, serial number XX377, in a friendly fire incident, killing all four occupants. Cardiff, on the lookout for aircraft flying supplies to the Argentine forces occupying the Falkland Islands, misidentified the helicopter as an enemy Lockheed C-130 Hercules. The loss of the helicopter was initially blamed on enemy action, but a subsequent inquiry found a missile from the Cardiff to be the cause.