MacMahon is one of the best known and most distinguished names in Ireland. In Irish Mac Mathghamha, or in ultra-modern spelling MacMahuna, it is said to be derived from the Irish word for a bear. It is borne by two quite distinct septs. One of these belongs to Co. Clare, in which county is now the most numerous name. These descend from Mahon, son of Murtagh Mor O’Brien, King of Ireland (D. 1119), and the last inaugurated Chief of the Name fell at the battle of Kinsale in 1602. Their territory was Corcabaskin in West Clare. The Ulster sept of MacMahon in the thirteenth century became lords of Oriel on the decline of the O’Carrolls. It is associated chiefly with Co.. Monaghan, where the name holds third place in the county list. In fact, as is usually the case with old Gaelic families, their present-day representatives in Ireland (who are about ten thousand in number) are still to be found chiefly in their original territories – in this case Clare and Monaghan. There have been very many distinguished bearers of the name MacMahon. Bernard MacMahon (1680-1747), his uncle Hugh MacMahon (d. 1737) and his brother Ross Roe MacMahon (1698-1747) were all Archbishops of Armagh, having previously been bishops of their native Clogher. Of the five bishops who held the see of Clogher in the eighteenth century, three were MacMahons and two O’Reillys. Another earlier and very famous Bishop of Clogher was Heber MacMahon (1600-1650), a leader of the Confederate Catholics who actually commanded the Ulster army and died on the scaffold. Prominent in the same cause were Hugh McMahon, last chief of the Ulster sept, who was also beheaded, having been betrayed by Owen O’Connolly in 1641, and Col. Brian MacMahon, who fought at Benburb (1646) and was a member of the Supreme Council of the Confederate Catholics. A generation later the name appears in King James’s Irish army, in which Col. Art MacMahon’s infantry regiment was notable. subsequently many of these officers distinguished themselves in the service of France in the Irish Brigade. Later in that country there was John MacMahon (1715-1780), who was ennobled as Marquis d’Eguilly, of the Clare MacMahons, and his grandson Patrick MacMahon (1808-1893) who was President as well as Marshal of France. It is probable that Charles Patrick Mahon (1800-1891), better known as “The O’Gorman Mahon”, was a descendant of the Clare MacMahons. Mahon, however, though sometimes used as an abbreviated form of MacMahon, is as a rule a distinct name, being that borne by two septs located in connacht, one in the diocese of Kilmacduagh (south Galway) and the other as erenagh family of Killaraght, Co. Sligo, who were hereditary custodians of the Cross of St. Attracta. This surname, O Mochain in Irish and properly Mohan in English, spread in to Munster, where it was usually anglicized Vaughan. Though Vaughan is, of course, a common Welsh name most of our Irish Vaughans are in fact of this Gaelic stock.