Outside of Ireland, the "Dwyer" form of the name, without the "O" prefix, is more widely used, but both share the same clan roots. The dropping of the prefix dates back to the mid-seventeenth century, and was brought about by the policy of the English government to suppress the ancient Irish Celtic culture and clan system.

The original form of the name in the Irish language, and still widely used today, is O'Duibhir (pronounced O Dweer), meaning descendant of Duibhir, an ancestor who, by tradition, lived sometime around the tenth century. The precise meaning of this ancestor's name remains obscure - 'black skirt' has been suggested, but the common modern consensus is 'black and dun-coloured', probably referring to a mixture of hair colouring on the head and face as a personal characteristic.

While the O'Dwyers are strongly associated with south Leinster (the most easterly of Ireland's four provinces), it is beyond doubt that the main territory under their control was an ancient district called Kilnamanagh in County Tipperary, Ireland. The name still survives as a modern civil barony, and extends over perhaps 100 sq. miles in the mountains between Limerick, Tipperary, Cashel and Thurles. The crumbling ruins of nine of the O'Dwyer castles can still be seen on the Kilnamanagh landscape even today.

The territory of Kilnamanagh was lost to the clan in the aftermath of the Cromwellian wars of the mid-seventeenth century, following the ill-fated capture of Cashel, the ancient Celtic seat of the Munster kings, by Philip O'Dwyer, the last clan chief. The clan was scattered - a few were permitted to take up lands west of the River Shannon in County Clare and other places, but the majority were part of the estimated 7,000 Irish who were exiled to mainland Europe with Colonel Edmund O'Dwyer, the leader of the Munster forces who surrendered to the Cromwellian army at Cahir, Co. Tipperary in 1652. Doubtless, many of their descendants are to be found across Europe today, though the surname has probably been modified to suit local pronunciation. For example in France, it appears as 'Haudoire'. It is interesting to note that many O'Dwyers remained or returned to their ancient territory of Kilnamanagh, because, even today, the highest concentration of the surname in the world is still to be found in this corner of Tipperary.

As with most Irish clans, the O'Dwyers have a legendary ancestral line which traces the pedigree of the chiefs from before recorded history (to no less a figure than Adam!) down to the seventeenth century. These genealogies were originally handed down by word of mouth by the Fili, or poet of each clan, and were first published in book form by Geoffrey Keating in the mid-seventeenth century.

For a more comprehensive history, see 'The History of the O'Dwyers' by Sir Michael O'Dwyer (The Celtic Bookshop, 2000, ISBN 0-9534683-2-1) available from The Celtic Bookshop, Rutland St., Limerick, Ireland. (celticbk@iol.ie).