His father was an undertaker in the Plantation of Munster after the Desmond Rebellions[3] and was in 1585 granted the seignory of Newcastle, 10,500 acres, in the Barony of Connello, in the western part of County Limerick.
[4][5][6] Between 1598 and 1611 Courtenay bought the seignories of Mayne[7] (south east of Newcastle) and Beauly (also called Muskrinownan)[8] from Sir Henry Oughtred's heirs, increasing his lands in Munster from 10,500 to 33,678 acres.
Her uncle Captain Edward Berkeley had in 1585 or 1586 been made Constable of Askeaton Castle,[11] which had been taken by the English in April 1580 soon after the beginning of the Second Desmond Rebellion.
[16] His elder brother Francis Courtenay became de jure Earl of Devon and inherited the English lands.
In May and June 1642, Courtenay defended King John's Castle, Limerick, against the Munster rebels under General Garret Barry, Patrick Purcell of Croagh, Lord Muskerry, and Maurice Roche, 8th Viscount Fermoy.