Charles O’Conor, Irish writer and antiquarian who is enormously influential as a protagonist for the preservation of Irish culture and history in the eighteenth century, is born on January 1, 1710 in Killintrany, County Sligo. He combines an encyclopaedic knowledge of Irish manuscripts and Gaelic culture in demolishing many specious theories and suppositions concerning Irish history.

O’Conor is born into a cadet branch of the land-owning family of O’Conor Don and is sent for his education to Father Walter Skelton’s school in Dublin. He grows up in an environment that celebrates Gaelic culture and heritage. He begins collecting and studying ancient manuscripts at an early age.

His marriage brings him financial stability so that he can devote himself to his writing, but he is widowed in 1750, within a year of his father’s death. When his eldest son Denis marries in 1760, he gives up the residence at Bellanagare to him and moves into a small cottage that he had built on the estate. He devotes the remainder of his life to the collection and study of Irish manuscripts, to the publication of dissertations, and especially to the cause of Irish and Catholic emancipation.

O’Conor is well known in Ireland from his youth as a civil-tongued, but adamant, advocate of Gaelic culture and history. He garners fame outside Ireland through his Dissertations on the ancient history of Ireland (1753), which is generally well received. When Samuel Johnson is made aware of it, he is moved to write a letter to O’Conor in 1755, complimenting the book, complimenting the Irish people, and urging O’Conor to write on the topic of Celtic languages.

The book is less well received in some Scottish circles, where there exists a movement to write Celtic history based upon Scottish origins. When James Macpherson publishes a spurious story in 1761 about having found an ancient Gaelic (and Scottish) cycle of poems by a certain “Ossian“, among the critics who rejects it as false is O’Conor, as an inclusion in the 1766 rewrite of his 1753 work. While the issue was laid to public rest by others, notably Samuel Johnson, the issue is laid to intellectual rest by O’Conor in 1775, with the publication of his Dissertation on the origin and antiquities of the antient Scots. The fact that the issue occurs provides O’Conor the opportunity to establish Ireland as the source of Gaelic culture in the minds of the non-Irish general public.

O’Conor’s later life is that of the respected dean of Irish historians. He continues to write as always in favour of ideas that he favours and are consistent with the historical record, and against any and all ideas that are inconsistent with the historical record, including those of other Irish historians. Such is his esteemed reputation that even those whom he challenges would include his challenges in the next edition of their own books. He continues to collect, study, and annotate Irish manuscripts. Upon his death in Bellanagare, County Roscommon on July 1, 1791, his collection becomes the first part of the Annals of the Four Masters at the Stowe Library. In 1883 these are returned to the Royal Irish Academy library.

His unfinished History of Ireland, that Johnson had encouraged in 1777, is destroyed on his instructions at his death.