The O’Flaherty family are descended from one Flaithbheartach mac Eimhin who lived in the 10th century. Although originally settled on the eastern side of what is now County Galway, they were later driven further west and came to control much of Connemara. But like many other such tribes, they were almost constantly striving to expand the area under their authority and it is said the mediaeval walls of Galway city carried the inscription ‘From the ferocious O’Flahertys O Lord Deliver Us.’ By this time, one of their strongholds was Bunowen Castle, County Galway strategically located by the Hill of Doon and overlooking the Atlantic Ocean.

In the sixteenth century, Bunowen and its surrounding lands were controlled by Dónal ‘an Chogaidh’ Ó Flaithbheartaigh (Donal of the Battle) who in 1546 married Gráinne daughter of Eoghan Dubhdara Ó Máille, chief of the Ó Máille clan in neighbouring County Mayo: she is also known as Grace O’Malley, the Pirate Queen. The couple had three children before Dónal was killed in battle in 1560: a few years later Gráinne left Bunowen and settled instead on Clare Island in her own county. But the castle remained in the family’s ownership until the 1650s when it was captured by the Cromwellian army and the O’Flahertys dispossessed. Bunowen was then given to Arthur Geoghegan whose own lands in County Westmeath had been taken from him before he was transplanted to the west of Ireland. The Geoghegans subsequently married into a local family, the Blakes who were one of the Tribes of Galway, and so became integrated into the region.

In 1808 John David Geoghegan of Bunowen petitioned the British crown for permission to change his surname. The family had long believed itself descended from the prehistoric Irish king Niall of the Nine Hostages and therefore wished to take the name of his descendants. Accordingly they were granted the right to call themselves O’Neill. It is perhaps for this reason that, having assumed control of the Bunowen estate following his father’s death in 1830, John David’s son Augustus John O’Neill embarked on an ambitious building programme to enlarge the house. During the previous four years he had served as an Member of Parliament for the English constituency of Kingston-upon-Hull but had not stood for re-election. There were rumours that one reason for his unwillingness to face the electorate a second time was due to a gambling scandal or unpaid bills, but these allegations were not substantiated. In any case, he did overstretch his resources on Bunowen and, like so many others, in the aftermath of the Great Famine he was obliged to sell his property. In 1853 it passed into the hands of Valentine O’Connor Blake of Towerhill, County Mayo who used Bunowen as a summer residence. The castle was intact a century ago but at some date thereafter abandoned. It now stands a gaunt ruin, still gazing out to the Atlantic as it did when occupied by the ferocious O’Flahertys.