Located on private lands, in the townland of Illion, in the south of the island, near a prehistoric promontory fort. Robert Cunnyngham was the constable of Doe Castle, which had been captured in 1650 by Cromwellian forces from Derry. It was during this turbulent time, that he led a platoon of soldiers to commit a murderous atrocity at, what is now known as, The Cave of Slaughter on Arranmore, where he and his men murdered 63 catholic men, women, and children during the Cromwellian religious genocide. Cunnyngham continued his murderous campaign, until he met his end at Doe Castle, at the hands of two vengeful Arranmore men, survivors from the Arranmore massacre.