On April 9, 1990, the Provisional Irish Republican Army (IRA) detonates a massive improvised land mine under a British Army convoy outside Downpatrick, County Down, Northern Ireland. Four soldiers of the Ulster Defence Regiment (UDR) are killed, the regiment’s greatest loss of life since 1983.

The Provisional IRA had been attacking British Army patrols and convoys with land mines and roadside bombs since the beginning of its campaign in the early 1970s. The deadliest attack was the Warrenpoint ambush of August 1979, when 18 soldiers were killed by two large roadside bombs near Warrenpoint, County Down. In July 1983, four soldiers of the local Ulster Defence Regiment (UDR) were killed when their vehicle struck an IRA land mine near Ballygawley, County Tyrone. It was the UDR’s biggest loss of life up until then.

On the morning of April 9, 1990, two UDR armoured landrovers are traveling from Abercorn Barracks to Downpatrick. An IRA unit has planted a 1,000-pound improvised land mine in a culvert under the Ballydugan Road, just outside the town. The unit waits in woodland overlooking the road, about 350 feet away. As the landrovers drive over the culvert, the IRA detonates the bomb by command wire. The huge blast blows the vehicle into a field and gouges a large crater in the road, 50 feet wide and 15 feet deep. A witness describes “a scene of utter carnage.” Four soldiers are killed: Michael Adams (23), John Birch (28), John Bradley (25), and Steven Smart (23). It is the biggest loss of life suffered by the UDR since the 1983 Ballygawley land mine attack. The soldiers in the other landrover suffer severe shock and are airlifted to hospital. According to police, a civilian driver also suffers shock and another receives cuts and bruises.

The bombers escape on a motorcycle which had been stolen in Newry a week earlier, and is later found abandoned in Downpatrick. The IRA issues a statement saying the attack was carried out by members of its South Down Brigade.

British Prime Minister Margaret Thatcher says on BBC Radio, “You take these murders of these four people today alongside those decisions in the Supreme Court of the Republic not to extradite those accused of violent crime – and one is very, very depressed.” Charles Haughey, the Taoiseach of the Republic of Ireland, condemns the attack as an “atrocity.”

A 23 year-old man is later sentenced to 15 years in prison for the attack. He had driven a scout car for the bombers when it was planted the day before the attack.