About 1350, at the site of a
ráth in the Castlereagh Hills, Aodh Flann O’Neill is said to have built the castle from which the townland was named. Aodh was of the
Clandeboye, a branch of the
O'Neill dynasty who colonised the area from the west.
Con MacShane O'Neill raided Belfast from the castle after Christmas 1602, leading to retributions from the Elizabethan settlers there. In 1615, he was reduced to selling the
manor comprising the castle and grounds to
Moyses Hill, ancestor of the
Marquesses of Downshire, who still exercised jurisdiction there in the 1840s. The title of
Viscount Castlereagh was created in 1795 for
Robert Stewart, Baron Londonderry; when he was promoted to Earl of Londonderry in 1796, "Viscount Castlereagh" was the
courtesy title of
his son, infamous for suppressing the
Irish Rebellion of 1798.
Population Population of townlands was published at censuses from 1841 to 1926. ==Places named after the townland==