This most interesting surname, of Old Gaelic origin, is the Anglicized form of the Gaelic "O'Longargain", of uncertain etymology. This Irish sept inhabited north-east Thomond, that is that part of Tipperary which lay on the east side of Lough Derg, in pre-Norman times. Later the Anglo-Norman Butlers forced them southwards to Cashel and Cahir, where they have remained in considerable numbers up to the present day. The surname itself, which first appears in records in the mid 12th Century (see below), is also found in the modern idiom as "Londrigan". The chief of the sept resided at Cahir. Their importance in Irish History is due to the fact that they provided a number of leading ecclesiastics from the 12th to the 15th Century, no less than six of these being archbishops or bishops, two of Killaloe and three of Cashel. The family O'Lonergan also provided harpers to the O'Kellys of Ui Maine. They possessed a small patrimony at Ballynabanaby in south-east Galway, circa 1400. Thomas S. Lonergan (born 1861) was a notable Irish-born American poet and politician, and Anne Lonergan was an Irish nun imprisoned during the French Revolution. The family also bears a Coat of Arms which depicts on a blue chevron three gold estoiles, in chief two red arrows in saltire pointing downward. The first recorded spelling of the family name is shown to be that of Donell O'Lonergan, Archbishop of Cashell, which was dated 1152, in the "Records of the Council of Kells", during the reign of Irish Kings in opposition, disputed succession. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.