This ancient Irish name originated in Ulster, where it is still most prevalent today in the Anglicized forms Shiels, Shiel, Sheils, Shields or Sheilds, from the Gaelic name "O Siaghail", "O Siadhail", descendant of Siadhail. The O' Shiels claim descent from Niall of the Nine Hostages, but are known for their hereditary association with medicine rather than as a territorial sept, Murtagh O' Shiel, recorded below, being the most well known as physician to MacCoughlan in the early 16th Century in County Offaly, where a branch of the family had a seat at Ballysheil. Notable bearers of the name "Shiel" include Connach O' Shiel, Abbot of Ballysodare, appointed Bishop of Elphin by Henry V111 in 1545, who rejected the new doctrines until his death in 1552. One of the families of O' Shiels who settled in Nantes, France, after the Jacobite defeat at the Battle of the Boyne in 1690, was admitted to the ranks of the French nobility in 1775. The first recorded spelling of the family name is shown to be that of Murtagh O' Shiel, which was dated circa 1548, in the Records of County Offaly, during the reign of King Edward V1, known as "The Boy King", 1547 - 1553. 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.