The Battle of Dysert O'Dea, which drove the Anglo-Normans from the region for over 200 years, took place at this site on 10 May 1318. The castle was built between 1470 and 1490 by Diarmaid O'Dea, Lord of Cineal Fearmaic. The Earl of Ormond took the castle from the O'Dea clan in 1570 by force. By 1584, however, they had regained it. At that time, Domhnall Maol O'Dea was listed as owner. Domhnall supported the northern Chiefs in the Nine Years' War of 1594-1603 and subsequently Dysert Castle fell to the Protestant Bishop of Kildare, Daniel Neylon, who in 1594 bequeathed it to his son, John. The castle soon returned to the O'Dea clan. Conor Cron O'Dea supported the Confederates and participated in the successful siege of Ballyalla Castle in 1642.