The History of

the Dempsey Name

The surname in Irish is O'Diomasaigh, from diomasach, meaning proud. The O'Dempseys are of the same stock as the O'Connors of Offaly and were a powerful sept in theterritory lying on the borders of Leix and Offaly known as Clanmalier. Hence the title Viscount Clanmalier bestowed by James I of England on Terence O'Dempsey, the family being then and in the reign of Elizabeth I consistently pro-English.However, they took the Irish side later on in the seventeenth century: Edmund O'Dempsey, Bishop of Leighlin, Lewis O'Dempsey, Viscount Clanmalier, and Barnabas O'Dempsey were prominent members of the Confederation of Kilkenny and with Lysaght O'Dempsey, were exempted from pardon by the Cromwellian victors in 1652: their loyalty to the Catholic King James II resulted in the loss of their estates. In earlier times, too, they were distinguished in the defence of their country and O'Dempsey, Chief of Offaly, was one of the few Irish leaders who could boast of having defeated Strongbow in a military engagement, which he did in 1172, Strongbow's son-in-law, de Quenci being killed in the battle. Dermot O'Dempsey (d. 1193), Chief of the Name, founded the Cistercian Abbey at Monasterevan. St. Evin, it may be mentioned, who established the church at Monasterevan, a place which bears his name, was the patron saint of the O'Dempseys. The Dempseys, too, were notable among the priests of the penal times, one of the John Dempsey, a relative of Viscount Clanmalier, beingBishop of Kildare.