The IRA bombing campaign

Andy Oppenheimer,
CBNW & CBNW Xplosive

(Cover picture: the Grand Hotel in Brighton following the IRA bomb attack; the photo was taken on the morning of October 12 1984, some hours after the blast. Source: D4444n at en.wikipedia)

30 years of IEDs

The worst terrorist attacks on British soil remain the transit bombings on July 7, 2005, in which 52 died and 770 were injured, and the biggest threat still emanates from violent Jihad. But for those who lived through the 30-year bombing campaign waged by the Provisional IRA (PIRA) in Northern Ireland and the UK ‘mainland’, bombings were at times commonplace. As they occurred mainly in the pre-Internet, pre-24-hour TV news era, they received nothing like the instant, ubiquitous publicity that would obtain today.

Until the Iraqi insurgency and the dawn of ISIS the full range of IEDs, explosives, mechanisms, and tactics, techniques and procedures (TTPs) used by PIRA eclipsed any other terrorist group in history. From 1970 to 2005, 19,000 IEDs were exploded on British territory: that’s one every 17 hours.

Some 14,540 kg of explosives were deployed: gunpowder, dynamite (19th century), gelignite, ammonium nitrate (AN), potassium chlorate, Semtex, aluminium powder, iron oxide, carbide, 808, TNT, ammonal, and sodium chlorate/nitrobenzene (‘Co-op mix’). ANFO (ammonium nitrate/fuel oil) was boosted by commercial explosives - first gelignite and then in the 1980s, Semtex from Libya. In August 1972 alone, 2,660 kg of explosives were detonated in 126 bombings, mostly in the province.

The "Engineering Department"

From early ‘own goals’ - in which bomb-makers got blown up by their own devices - and sometimes dozens of others with them, by the early 1970s the PIRA had its own R & D programme and a separate elite ‘division’ of bomb-makers - the ‘Engineering Department’. Using training grounds in Counties Donegal and Armagh, it developed an unprecedented level of adapted technical IED expertise.

Information on IED-building was passed through generations, through the nationalist community, from US and British Army manuals, training with other groups, learning ‘on the job’, infiltrating organizations such as the Post Office and NASA, and through developing and adapting abilities to improvise and innovate.

Targeting influenced technology

Their IEDs were developed based on their intended targets – mainly economic and infrastructure in the province and the mainland; British Army, RUC and mainland police, officials, politicians, judges, collaborators or anyone associated with the British presence in Ireland.

IEDs increased in sophistication, from crude nail bombs and petrol bombs to advanced VBIEDs with multiple timers and booby traps. IEDs were disguised as milk churns, haystacks, books, food cans, tape cassette boxes, beer kegs, traffic cones, fire hydrants, cigarette packets, etc. Shop-window dummies were left on car seats to disguise the fact the car was carrying a bomb.

While mass casualties in the manner of al-Qaeda were rarely the aim, civilians were killed and injured. Out of 3,700 who died and tens of thousands injured in the three decades of violence in Northern Ireland, the IRA murdered about 1,800 civilians and members of the security forces. Civilians died after false or inaccurate warnings.

Warrenpoint and Mountbatte23

To pick just one day of deadly IED innovation: 27 August 1979. PIRA first used a radio control transmitter to trigger, from the coast, a 22-kg IED they had secreted on the boat used by the Queen’s cousin, Earl Mountbatten, holidaying with his family at Mullaghmore, Ireland. He and three others were killed.

Just hours earlier, two AN/nitroglycerine/coal IEDs killed a convoy of 18 British soldiers - the worst toll in one bombing against the Army. An initial IED was hidden in a milk-churn on a trailer to ambush the Royal Marines convoy. It was triggered remotely by a model aircraft transmitter unit. The second, a 680-kg AN IED, blew up anyone taking cover behind the castle walls, who were also attacked by IRA snipers. Both IEDs were activated by a radio-control receiver-decoder device hidden in a Tupperware lunchbox, set on a Memopark timer.

City destroyers

PIRA advanced the car bomb - as more space for bulk explosive could be mounted in a vehicle. The massive VBIED was taken to extraordinary lengths in the City of London in the 1990s, epitomizing the PIRA maxim: “One bomb in London is worth 20 in Belfast.”

(IRA engineers began to make their own det cord by distilling out explosives from the Semtex mix.

These were extracted and washed with solvents, then poured into clear plastic tubing for the cord.

Photo by the author, IRA Inventory of Weapons, An Garda Síochána HQ, Dublin)

(Mercury tilt switch, taken from heating systems: a glass tube containing a blob of mercury with two terminals was mounted on the side of a plastic box, attached with a magnet underneath the driver's side. When the car drove off or went up or down a certain gradient, the mercury would move forward, make the connection and detonate the IED. Photo by the author, IRA Inventory of Weapons, An Garda Síochána HQ, Dublin)

Targeting the Government: Brighton and Downing Street

Another PIRA innovation was a long-delay timer purloined from a videorecorder (VCR - remember them?). This had its debut run in an attempt to blow up Margaret Thatcher and her Cabinet at the 1984 Conservative Party conference at The Grand Hotel, Brighton.

Set to explode on 12 October - 24 days, 6 hours, 36 minutes after it was hidden behind a hotel room bath panel - the VCR timer was converted to send an electrical impulse to the detonator. The explosive charge was limited to 30 kg due to the need for a long period of concealment at a very high-profile event. The VCR was ideal as a commercially produced, reliable, and very accurate timer.

The Mk 10 hits Number Ten

The second attempt at targeting the Government, on 7 February 1991, involved a multiple mortar attack on 10 Downing Street. Three bombs were launched from a firing position in a stationary van. They hit a tree and exploded 13 m short of target, forming a crater several metres wide and shattering the blast windows of the Cabinet room. Prime Minister John Major and his Cabinet dived under a table. As well as extensive damage to 11 and 12 Downing Street, two civil servants and two policemen were injured.

The biggest in PIRA’s homemade mortar series, the Mk10 fired a 15cm shell with 11 kg of Semtex or AN/nitrobenzene in gas-cylinder bombs as far as 300 m. The Downing St mortar used around 22 kg. It had ten 1.4m, 165cm-wide steel tubes set at varying angles for maximum target coverage, launched by a propulsion charge in the base. Oxyacetylene gas cylinders used for rural domestic heating had the tops and bottoms chopped off and bolted onto the flatbed of a hijacked truck, then linked to det wire and timers. Electrical initiation was used.

Factory-made IEDs: attacking infrastructure

Over 30 mass-produced devices seized by Gardai from the IRA’s Clonaslee ‘bomb factory’ in the Irish Republic in the mid-1990s were intended to take out 22 electrical substations -specifically, the transformer units - which channel almost all the electricity used in the London area. PIRA researched their intended targets and reconnoitred at least five substations. The 100,000-V environment meant the power would have to be shut down before bombs could be found and rendered safe. Had up to five transformers been disrupted, large parts of London would have been without power for days or weeks.

Housed in three-compartment timber-box IEDs, the power unit was a large battery for electrifying rural fences; a 3-kg Semtex block (middle compartment empty in picture); a 9 V timer used to turn on central heating at appointed times, which allowed 40 hours from devices being placed and their detonation, and a stand-by battery kept the clock going.

The clock kept on ticking until the IRA finally decommissioned its weapons in 2005. Now, the dissident republican ‘fission products’ of PIRA have nowhere near the level of its expertise and organisation - but are still taken seriously enough for the Threat level in Northern Ireland to remain at Severe.

Andy Oppenheimer is Editor-in-Chief of CBNW and CBNW Xplosive magazines and author of IRA: the Bombs and the Bullets: A History of Deadly Ingenuity (Irish Academic Press, 2008). He is a Member of the International Association of Bomb Technicians & Investigators and an Associate Member of the Institute of Explosives Engineers.