The townland was named after the
Ollamh Érenn or Chief Poet of Ireland,
Dallán Forgaill, who composed the "Amhra Coluim Cille" a panegyric on Saint
Columba in c.597 in
Portloman townland, which is two townlands to the east of Kildallan. Dallan was not a member of the clergy so he probably donated the townland to the church. In medieval times the land was owned by the O'Casey or O'Cathasaigh clan of Saithne (now called Sonna). The
Annals of the Four Masters contain several references to them under the years 1018, 1023, 1086, 1140, 1146, 1153, 1160, 1171, 1179, etc. At the time of the Norman Invasion of Ireland, King
Henry II of England granted to
Hugh de Lacy, Lord of Meath, the lands of Ó Maoilsheachlainn, king of Meath in return for the service of 50 Knights. As one of de Lacy's barons,
Risteárd de Tiúit received large grants in Westmeath and Longford. His descendants became the barons of Moyashell, in Westmeath. De Lacy conferred on the Tuite family the castle of O'Casey (Irish Ó Cathasaigh), chief of Saithne, now Sonna in Westmeath. This senior branch of the family became Protestant in order to hold on to their lands and remained on the lands until they moved to Britain in the 1920s. Pender's Census of 1659 states there were 8 people aged over 15 in the townland, all of English extraction, (In general the percentage of the Irish population aged under 15 runs at about 20% so the total population of Kildallan in 1659 would have been roughly about 10). An Inquisition held at Mullingar on 4 April 1665 spells the name
Kildolan and traces the ownership of the townland from the early 17th century. A further Inquisition held at Kilbegan on 26 August 1679 spells the name
Killdolan and traces the ownership of the townland from the early 17th century. A map published c.1770 spells the name as
Killdollan and depicts the holding of each tenant in the townland. The Tithe Applotment Books of 1833 spell the name as
Kildollan.
Griffith's Valuation of 1857 lists 21 landholders in the townland. The townland remained in the ownership of the Tuite family down to the 20th century. A Chancery decree dated 30 June 1873 spells the name as
Kildollan South. The book
Hibernia Venatica by Maurice O'Connor Morris published in 1878 describes a fox hunt through
Kildollan Gorse. In the
1901 census of Ireland, there were fifteen families listed in the townland. In the
1911 census of Ireland, there were sixteen families listed in the townland. A description of Kildallan in 1938 is viewable on the Dúchas website. ==Antiquities==