On 3 May 1921, Maguire led an ambush on a Royal Irish Constabulary patrol in Tourmakeady, County Mayo, killing four. Maguire's flying column then made for the Partry Mountains. One account claimed that the column were surrounded by over 700 soldiers and policemen guided by aeroplanes. Maguire was wounded and his adjutant killed, but the column managed to escape with no further casualties. British casualties were not revealed but were believed to have been high. Some recent research has raised the possibility that fewer than forty British soldiers were in the vicinity and that Maguire's column was forced to abandon their weapons with only one British officer wounded.