On 17 July 1975, Major Peter Willis, the Green Howards company commander in Crossmaglen was accompanied by three British soldiers, all of whom were bomb disposal experts.

As they did so, a 70 lb (32 kg) bomb that had been packed into a beer keg and buried in the ground, was detonated by command wire from about 400 yd (370 m) away.

[2] The soldiers killed were Major Peter Willis (37), Edward Garside (34), Robert McCarter (33) and Calvert Brown (25).

British Secretary of State for Northern Ireland, Merlyn Rees, condemned those responsible for the killings.

Thompson maintains, however, that he was forced to sign the statement after receiving beatings and threats to his family.