During the Border Campaign, four IRA men were preparing a landmine in a cottage on the side of a hill overlooking the border. The cottage was owned by a fifty-five year-old civilian, Michael Watters, who had allowed them to use his cottage for their operation. The four IRA members were Oliver Craven, Paul Smith, George Keegan and Patrick Parle. The likely cause of the detonation was a malfunction with the timing mechanism, and all five were killed instantly. It was the biggest loss to the IRA since the Irish civil war. Garda Síochána found three Thompson sub-machine guns and magazines at the scene.