By 1973, the IRA had a problem. British searches and surveillance were tightening across Northern Ireland, and planting a bomb at a military target without being caught had become nearly impossible. In March of that year, the organisation introduced a solution that solved the operational problem while creating a moral catastrophe: force someone else to carry the bomb. The first proxy attacks targeted off-duty members of the British security forces or people who worked for them. In 1975, an employee of Northern Ireland's Forensics Laboratory in Newtownbreda was forced to drive an explosives-laden car to his own workplace. Damage was moderate. Operations resumed within days. The tactic had been proven. Over the following two decades, it would mutate, escalate, and eventually exhaust the patience even of communities sympathetic to the republican cause.

On 24 October 1990, the IRA launched three coordinated proxy attacks. In County Donegal, on the southern side of the border, men deemed by the organisation to be collaborators were taken from their homes while their families were held at gunpoint. In Newry, the IRA's South Down Brigade seized James McAvoy, sixty-five years old, a Catholic man who ran a filling station beside his house. His crime, in their reckoning, was serving petrol to RUC officers. In Omagh, another man was strapped into a car and forced to drive toward Lisanelly Camp. The October 1990 attacks crossed a threshold that previous proxy operations had not. Catholics turned against the IRA. The Catholic Church condemned the attacks from the pulpit. Even some republican supporters recoiled. Journalist Ed Moloney would later write that as an operation calculated to undermine the IRA's struggle and damage Sinn Féin politically, it had no equal.

The proxy bomb has often been compared to a suicide bomb, but the comparison falls apart the moment you sit with it. A suicide bomber chooses, however terribly. A proxy driver chooses nothing. The man behind the wheel was not a soldier and not a volunteer. He was a husband, a father, a shopkeeper, a taxi driver, a Garda off duty, a civilian whose family had been taken from him an hour earlier. Some drivers managed to abandon their vehicles in open fields. Others shouted warnings as they approached checkpoints, giving soldiers seconds to scatter. A few died at the wheel. The tactic depended on something the IRA's planners apparently never fully reckoned with: the people watching at home, the neighbours who knew the drivers' names, the communities who saw exactly what was being done in their name.

After October 1990, the IRA tried to walk it back. Several more proxy bombings were planned and then quietly cancelled. The final IRA use of the tactic came on 24 April 1993, when two London taxi drivers were forced to drive bombs toward Downing Street and New Scotland Yard. Both drivers shouted warnings and abandoned their vehicles in time. There were no casualties. Yet the technique did not die with the Troubles. Training given to FARC by former Provisional IRA members carried the method to Colombia, where in 2003 three brothers in Arauca province were forced to drive car bombs into military checkpoints, each told the others would die if he refused. One brother was killed. The whereabouts of the third were still unknown by December that year. The tactic crossed an ocean. The grief travelled with it.

The Donegal countryside south of Derry, where many of these operations originated or ended, is among the most peaceful-looking landscape in Europe. Hedgerows, small fields, a few houses set back from the road. The Foyle estuary opens north toward the Atlantic. It is easy to forget, flying over it now, that for thirty years this border was the most surveilled and most contested in Western Europe. The proxy bomb is one of the reasons it ended where it did. The community that the IRA expected to support its hardest tactics turned out to have limits. Those limits were drawn in 1990, in driveways across South Armagh and East Tyrone, by ordinary people who watched their neighbours forced to drive bombs they had not built and did not want.