The townland name is an anglicisation of the Gaelic placename "Rath Caolain" which is usually given as 'Keelan’s Fort' but a more likely explanation is Rath Caolán, meaning 'The Fort of the Little Narrow Place', as the townland is squeezed between the Shannon–Erne Waterway on the east side and Slieve Rushen on the west side.
The oldest surviving mention of the name is in the 1609 Ulster Plantation Baronial map where it is spelled Rakellan.
Its chief geographical features are the Shannon-Erne Waterway which flows north along its eastern boundary and a foothill of Slieve Rushen mountain reaching to 228 feet (69 m) above sea-level.
An Inquisition held in Cavan Town on 20 September 1630 stated that Walter Talbot's lands included one poll in Rathkillan.
[5] James Talbot married Helen Calvert, the daughter of George Calvert, 1st Baron Baltimore of Maryland, USA, in 1635 and had a son Colonel George Talbot who owned an estate in Cecil County, Maryland which he named Ballyconnell in honour of his native town in Cavan.
[6] Gwyllym's name first appears in the area as the owner in the 1652 Commonwealth Survey, which lists the townland as belonging to Captain Gwilliams.
After the restoration of King Charles II to the throne in 1660, James Talbot tried to have the Ballyconnell estate restored to him but a final grant was made to Thomas Gwyllym in August 1666,[8] which included 107 acres-2 roods-32 perches in Gortewee alias Gortevill alias Rathkylan, so the townland seems to have been merged with Gortawee at that time.
In 1856 they sold the estate to take advantage of its increased value owing to the opening of the Woodford Canal through the town in the same year.
The estate, including Rakeelan, was split up among different purchasers and maps & details of previous leases of the sold parts are still available.
[12] The Tithe Applotment Books for 1827 list the following tithepayers in the townland- Faris, Bedel, McAvinue, Reilly, Hyland, McDaniel, Roe, Sturdy, Plunkett, Benison, McGuire, Montgomery, Fitzsimons, Adbort.
[13] The Ordnance Survey Name Books for 1836 give the following description of the townland- Rath Caoláin, 'Keelan's fort'.