Montmorency, Hervey de (a. 1130–p. 1185), son of Bouchard de Montmorency and his wife Adeliza, was a Frenchman who led one of the first contingents of Anglo-Normans to Ireland in 1169. He appears to have had a long career in the service of the French king, but by 1169 had come to England and entered the service of his nephew Richard de Clare (qv) (Strongbow), earl of Strigoil. His inclusion in the expedition of Robert fitz Stephen (qv) to Ireland appears to have been as a representative of his nephew in order to gauge the feasibility of Strongbow's interest in Ireland. He actively supported Diarmait Mac Murchada (qv), taking part in Mac Murchada's raids into Offaly, for which he was granted two cantreds between Wexford and Waterford. Montmorency joined Strongbow as soon as the earl arrived in Ireland, and was sent by his nephew as an ambassador to Henry II (qv) in order to come to terms with the king. When Henry came to Ireland, Montmorency served as the marshal of his army and was granted Dunbrody by the king.
When Strongbow left to serve the king in Normandy (1173), he left Montmorency as his deputy. As such, Montmorency was confronted by increasingly hostile Gaelic magnates, culminating in an attack on Strongbow's base in Kilkenny. Early in 1174 Montmorency and Strongbow led a retaliatory attack into Munster but were heavily defeated near Thurles and had to retreat to Waterford. Later that year, Strongbow was forced to replace Montmorency (who had largely alienated the earl's troops) with Raymond fitz William (qv), although he consoled his uncle with the office of constable of the lordship of Leinster. Montmorency spent much of his career in Ireland in competition with fitz William, and even appears to have gone as far as to accuse him of treason before the king in 1175. Because of this, Gerald of Wales (qv) took every opportunity to blacken Montmorency's name in the ‘Expugnatio’, putting a speech suggesting the murder of captives into his mouth, and blaming him for the disastrous 1174 campaign in Munster. Montmorency was replaced as constable of Leinster by fitz William after the latter lifted the siege of Waterford, and this may have led him to level the accusations of treason against his rival.
The rift with fitz William was partially healed when Montmorency married Nesta, a daughter of Maurice fitz Gerald (qv), but his position in Ireland was very much dependent on the patronage of Strongbow, after whose death (1176) Montmorency returned to England. In 1178 he made a grant of all his lands in Ireland to the Cistercians, and sometime after 1179 he retired, becoming a monk in Christ Church, Canterbury. According to a later obit he died on 12 March, but the year is uncertain. After his death his body was removed from Canterbury to Dunbrody. Despite his animosity towards Montmorency, even Giraldus recognised him as one of the four principal conquerors of Ireland; but like several of his contemporaries, Montmorency left no legitimate heirs, and his successes died with him.