[5] Tradition states that Dunmore (Irish dún mór, "great hillfort") was a lesser residence of the ancient Kings of Connacht.

[6] The first castle at Dunmore was built by De Birmingham family in the early 13th century as a bulwark against Gaelic Irish attacks.

[citation needed] In 1315 the castle was damaged by Rory O'Conor during the Bruce campaign in Ireland.

[citation needed] Most of the present structure dates from the early 14th century, i.e. the reigns of Edward II and III as Lords of Ireland: it was a two-storey hall keep.

[citation needed] The de Berminghams rebelled against Queen Elizabeth I and the castle was taken from them in 1569 by Sir Henry Sidney, Lord Deputy of Ireland, although it was later returned.