Ní Chonaill, Eibhlín Dhubh (c.1743–c.1800), poet, was born in Derrynane (Doire Fhionáin), Co. Kerry, one of the twenty-two children of Máire Ní Dhuibh (qv) and her husband, Domhnall Mór Ó Conaill of Derrynane House. Eibhlín and her sister Máire were twins; their younger brother Daniel Charles (qv), Count O'Connell (1745–1833), became known as ‘the last colonel of the Irish brigade’ in France, and the ‘Liberator’, Daniel O'Connell (qv), was the son of an older brother, Morgan (1739–1809). Eibhlín, whose epithet means ‘black-haired’, is conventionally named as composer of ‘Caoineadh Airt Uí Laoghaire’, the lament (‘keen’) for her husband, shot dead on 4 May 1773 at the age of twenty-six outside Carriganimmy (Carraig an Ime), near Macroom, Co. Cork, a few miles from their home at Rathleigh.
‘Caoineadh Airt Uí Laoghaire’, an oral-formulaic composition in Irish, consisting of rhymed groups of two-, three- or four-stressed lines, most of them addressed to the dead man, is known in several manuscript versions, all directly or indirectly derived from oral performances, and runs to 390 lines in Seán Ó Tuama's unsuperseded scholarly edition of 1961. It closely follows the established pattern of such laments, conventionally said to have been composed in performance in the period immediately following death, and bearing many similarities to oral ritual laments from other cultures. Internal evidence, however, together with its unusual length, suggests that this lament took shape over a longer period, and that several voices contributed passages to it. Some scholars have suggested that its origins are literary, and dispute Ní Chonaill's entitlement to be considered its author, citing her relatively privileged background, the poem's textual history, and the currency of this and other laments as propaganda in the fraught relations between catholics and protestants in late-eighteenth-century Munster. Certainly ‘Caoineadh Airt Uí Laoghaire’ and the story of Ó Laoghaire's killing and Ní Chonaill's subsequent actions spread widely in the years following his death.
The lament became known to Irish revivalists in 1892 when Mrs Morgan John O'Connell (née Mary Ann Bianconi, 1840–1908) wrote about Ní Chonaill (whom she calls ‘dark Eileen’) and Ó Laoghaire in her account of her husband's family, The last colonel of the Irish brigade. She included her own verse rendering of the lament as translated into English for her by the Rev. Peadar Ó Laoghaire (qv) of Doneraile (‘An tAthair Peadar’), and the Irish text, a version of over 350 lines, from a copy of a manuscript said to have been written from an oral performance by Norry Singleton, ‘a famous keener’ from Co. Cork. An Irish-language edition by Osborn Bergin (qv) appeared in the Gaelic Journal four years later, in June 1896. The lament thus became central to an evolving canon of Irish-language literature, where it has remained, continuing to stimulate debate and critical consideration. Emerging from the text and from editors’ comments as a fiery, aristocratic, Gaelic romantic heroine, Ní Chonaill has captured the imagination of generations of readers.
Nothing specific is known of Ní Chonaill's childhood, but her family was prominent, bilingual in Irish and English, and her brothers at least were literate in English from their youth; their home, Derrynane House, later restored as a museum, was large and well appointed. Art Ó Laoghaire (qv) (Arthur O'Leary) was her second husband, her first marriage, to an elderly Mr O'Connor, of Firies, Co. Kerry, having ended with his death within six months, when she was not yet sixteen. Her sister Máire married James Baldwin of Clohina, near Macroom, a convert to catholicism, in 1763 and, while visiting them, Ní Chonaill met the flamboyant and dashing Ó Laoghaire, some four years her junior. Ní Chonaill's family, catholics, mindful that their social standing depended on discretion, opposed the match, but the couple married in 1767 and settled at Rathleigh. Their son, named in the lament as Conchubhar (Cornelius O'Leary), was born the following year (d. 1846). Making his presence felt around Macroom, following service as a captain in the Hungarian hussars of the empress Maria Theresa, Art Ó Laoghaire fell foul of local magistrate and former high sheriff of Cork, Abraham Morris of Hanover Hall, in 1771, following which a reward of twenty guineas was offered for his capture.
By 1773, Ní Chonaill and Ó Laoghaire had a second son, Fear or Fiach (Ferdinando), and, according to the lament, she was again pregnant. Various accounts are given of the events leading to Ó Laoghaire's death, according to most of which Morris offered Art £5 for a horse which had just beaten his own – the maximum value allowed under the penal laws for any horse owned by a catholic – and, predictably, Ó Laoghaire refused to sell. He was proclaimed an outlaw, and fled. On 4 May Morris, with an escort of soldiers, came upon him at Carriganimmy. One of the soldiers shot and killed him, and the lament relates that his riderless mare galloped home, waking Ní Chonaill from sleep, and that she immediately rode back to the spot where he lay dead, began her lament and drank her husband's blood, as several medieval and modern texts say lamenting women have done in Ireland from early times.
On 7 June 1773 a coroner's court declared Morris guilty of Ó Laoghaire's death. He stood trial for murder at assizes the following September, but was acquitted. Tradition apparently based on the lament reports that Ní Chonaill travelled to London to seek royal action against her husband's killers. Nothing further is known of her life, but the date of her death is usually given as about 1800. Her son Cornelius O'Leary MD and his son Purcell O'Leary, barrister-at-law (1815–46), are buried with her husband in Kilcrea friary, Co. Cork.