What Is 10 Downing Street mortar attack

Overview

On February 7, 1991, the Provisional Irish Republican Army (IRA) launched a devastating mortar attack on 10 Downing Street, the official residence and workplace of the British Prime Minister. This coordinated assault targeted Prime Minister John Major and his war cabinet, who were gathered to discuss military operations during the Gulf War. The attack represented one of the most serious attempts to kill sitting members of the British government since the modern conflict between British forces and Irish republicans began.

The attack was executed with precision and coordination, involving the deployment of three homemade mortar shells from a van positioned approximately 200 yards from the target. The incident shocked the nation and demonstrated the IRA's continued capability and resolve to strike at the heart of British political power. Despite the proximity to the cabinet meeting and the destructive power of the explosives used, the attack miraculously resulted in no deaths among government officials, though it caused injuries and significant disruption to government operations.

How It Works

The mortar attack employed sophisticated tactics that demonstrated considerable planning and technical expertise. The following elements were critical to the operation:

• Launch Vehicle: A van was positioned at the junction of Horse Guards Avenue and Whitehall, approximately 180-200 meters from 10 Downing Street, providing an optimal firing position with adequate concealment and distance from security checkpoints.
• Mortar System: The IRA employed a Mark 10 homemade mortar, a self-designed explosive delivery system capable of accurate targeting over the required distance with sufficient payload guidance and firing control mechanisms.
• Projectile Specifications: Each mortar shell measured four feet six inches (1.4 meters) in length and weighed approximately 140 pounds (63 kilograms), with each carrying a 40-pound (18-kilogram) payload of Semtex plastic explosive.
• Firing Sequence: All three mortar shells were launched in rapid succession at 10:08 AM, with the explosive charges configured for maximum impact upon reaching their targets within the government complex and Cabinet Office.
• Incendiary Device: A pre-set incendiary device was incorporated into the attack plan, designed to ignite following the mortar launches and provide additional destructive force to compromise government infrastructure.

Key Details

The specific outcomes and trajectories of the three mortar shells varied significantly in their impact. Two shells landed on Mountbatten Green, a grassed area adjacent to the Foreign and Commonwealth Office, with one detonating and the other failing to explode on impact. The third shell struck its intended target more directly, exploding in the back garden of 10 Downing Street, approximately 30 yards (27 meters) from the Cabinet Office where the government meeting was being conducted. Had this final shell reached the Cabinet Office building itself rather than the garden, casualty estimates suggest the entire cabinet could have been killed.

The attack was officially claimed by the Provisional IRA, making it one of the most significant terrorist incidents against the British government in recent history. Prime Minister John Major, upon hearing the explosion from within the Cabinet Office, calmly remarked, "I think we had better start again, somewhere else," demonstrating remarkable composure under extraordinary circumstances. The cabinet was evacuated and the meeting reconvened less than ten minutes later in the Cabinet Office Briefing Room (COBR), allowing continuity of government operations during the Gulf War.

Why It Matters

• Political Impact: The mortar attack represented a direct challenge to the authority and security of the British state at its highest level, demonstrating that even the most protected government institutions remained vulnerable to determined adversaries with sufficient resources and planning.
• Military Capability: The attack showcased the IRA's advanced technical expertise and access to sophisticated materials, indicating substantial resources, training, and organizational capability well beyond typical militant groups operating in the United Kingdom.
• Timing During Gulf War: The coordinated attack during active military operations in the Gulf demonstrated the IRA's determination to pursue political objectives regardless of Britain's broader military commitments or international circumstances affecting national attention.
• Security Implications: The incident forced comprehensive reviews of British government security protocols and protective measures around Whitehall and other sensitive government locations throughout London.
• Escalation and Risk: Coming during a period of IRA activity, the attack illustrated the escalating risks and willingness of the organization to attempt mass-casualty attacks against senior political figures and government institutions.

The Downing Street mortar attack of February 1991 remains one of the most significant terrorist incidents in modern British history, representing a near-miss that could have decapitated the government during wartime. The attack ultimately failed in its primary objective but succeeded in demonstrating the IRA's continued operational capability and determination to strike at British political power, reshaping security considerations for decades to come.