Vallancey, Charles (1725?–1812), soldier and antiquary, may have been connected with the French noble family of d'Estampes de Vallancey (or Valençay), but the names of his parents are unknown. It has been stated he was born at Windsor, but in neither the records of Windsor parish church nor in those of St George's Chapel is the baptism of a Charles Vallancey recorded. Nor are the army lists helpful, since date and place of birth are not systematically recorded in them until the early nineteenth century. In 1802 Vallancey gave his age as 76, and the inscription on his tombstone described him as being in his eighty-eighth year when he died in 1812. It is possible Vallancey was born in Flanders, as stated by Warburton, and came to England as a child. According to Warburton he was educated at Eton, though this cannot be proved. Nevertheless it is likely he was educated at Eton; certainly he had an excellent classical education.
He joined the British army corps of engineers and was appointed ensign in 1746. It was probably in the same year he married his first wife, Mary Virgin, as his eldest son, George Preston, was born in 1747. Vallancey was posted to Cork sometime after 1750; according to the ordnance records in Dublin, he was an extra engineer in Ireland prior to 1759. His wife, who bore him nine children, died in Mallow, Co. Cork, in 1760. It may have been while he was in Cork that his interest in the Irish language was first aroused. In 1761 he succeeded to the post of major of engineers and soon afterwards was transferred to Dublin.
In 1763 he was elected a member of the Dublin Society, where for almost fifty years he was to play a prominent part. In the same year he married a lady of huguenot descent, Julie de Blosset (1714–83). It may have been his need for extra money (he had a large family to support and set in a fitting path of life) that led him to turn to translating texts and to acting as consultant on canal, harbour, and bridge projects. He published a treatise on inland navigation in 1763, and in 1766 a translation from the French of a work on stone cutting. The Queen's Bridge over the Liffey was built to his design. He brought out a report on the Grand Canal in 1771. In 1767 the 4th Viscount Townshend (qv), said to have been a friend of Vallancey at Eton, was appointed lord lieutenant, and for the next few years Vallancey was occupied preparing maps for Townshend's dispatches on Irish defence. He was also planning a military survey of Ireland. In 1776 his plan for the military survey was accepted, though confined to the south and south-west coast of Ireland. For the next twenty years he worked on the survey, which has been described as the most elaborate cartographic project in Ireland since the time of Sir William Petty (qv).
Vallancey was a man of great energy and industry, and side by side with his military duties he was active in cultivating his interest in the language, history, and antiquities of Ireland. In 1770 the first volume of his Collectanea de rebus Hibernicis, described by him as a collection of papers relating to Ireland, was published. Six volumes of the Collectanea appeared between 1770 and 1804. His Essay on the antiquity of the Celtic language was printed in 1772 and a Grammar of the Irish language in 1773 (2nd ed. 1782). The Grammar owes much to Muiris Ó Gormáin (qv), the well known scribe and translator and Vallancey's amanuensis. Vallancey's wife Julie died in 1783 and is buried in the huguenot cemetery, Merrion Row, Dublin. He remarried shortly afterwards and had one daughter, Catherine, by this marriage.
Several academic honours were bestowed on Vallancey in the 1780s. He received an LLD from Dublin University, was made a fellow of the Royal Society of Antiquaries, and was elected a Fellow of the Royal Society. He was a founder member of the RIA, which received its charter in 1786. Vallancey was sent to France in 1786 to replicate the copy of Sir William Petty's Down survey which had been captured on its way from Dublin to London by a French frigate in 1707 and which was lodged in the Bibliothèque du Roi in Paris. This task took him several months. Before going to Paris he had been promoted a colonel and had had A vindication of the ancient history of Ireland published.
By 1790 fears of a French invasion had increased and Vallancey was put in command of the forts in Cork harbour. His third wife and their daughter Catherine accompanied him to Cork, where he was promoted to major-general (1793) and remained until after the failure of the French invasion at Bantry Bay. Back in Dublin he prepared plans for the defence of the capital, but the collapse of the 1798 insurrection and the failed invasion by Humbert (qv) left him comparatively free of military duties. He was now a lieutenant-general (1798) and vice-president of the Dublin Society. He was to the fore in promoting some of the society's enterprises, in particular the transfer of the Botanic Gardens to Glasnevin, the establishment of a veterinary school, and the setting-up of the Farming Society. His third wife having died in 1799, he married fourthly (1802) Edith Plowman (d. 1809). There were two children of this marriage but only one, a son, survived into adulthood. His numerous family comprised six daughters and six sons. At least two of his sons joined the British army, and ‘pensions’ (dowries) for five of his daughters were granted by the crown. Around the turn of the century he finally became chief engineer. An engraving at the front of the sixth volume of the Collectanea bears the caption ‘Major-general Charles Vallancey, chief engineer of Ireland’. His last work, An essay on the primitive inhabitants of Great Britain and Ireland, originally intended to form part of vol. vii of the Collectanea, was published in 1812.
Vallancey was an affectionate father and a concerned commanding officer. He was often at the centre of controversy: he had immense industry and drive, and enthusiasm which was often not tempered by judgement. He has been criticised for ill-founded speculations on the affinities of the Irish language, but he lived before scholars had laid the foundations of comparative philology. His wish was to show Irish to be an ancient language worthy of respect, and his Irish grammar was influential in giving much needed prestige to the study of Irish. He died 8 August 1812 and was buried in the graveyard of St Peter's church, Aungier St.; St Peter's was demolished in the 1970s. A portrait of Vallancey by George Chinnery (1774–1852) hangs in the RIA and one by Solomon Williams (1760–1824) in the RDS.
Besides the works mentioned above, Vallancey was the author of a Dictionary of the language of Aire Coti or ancient Irish (1802) and The field engineer (translated from French, 1760). The RIA holds most of his papers; the NLI is also a valuable source for his career, holding both manuscript material and microfilm copies of his letters to the Home Office; and the BL contains his dispatches to the British authorities.