The provisional IRA's ceasefire ended abruptly with the Canary Wharf bombing in London in February 1996. Hopes that violence would not return to Northern Ireland were shattered by the explosion of two car bombs in the headquarters of the British Army in Ulster in October 1996. The second bomb specifically targeted medical staff treating casualties from the first explosion. This article describes the medical aspects of this incident, including the extensive use of critical incident stress debriefing, and emphasises the implications for the major incident plans of medical centres and military hospitals.