His appointment as Lord Chief Justice of Ireland is dated 25 June 1426, and for a short period his name occurs several times in the Calendar of the Irish Chancery Rolls.

One of the grievances which he was instructed to represent related to the insults and assaults made upon himself and Sir James Alleyn during their former mission, from which it may be concluded that their first visit to the court had not met with much success.

The other griefs for which the parliament prayed redress related to the frequent changes of governors and justices, the debts left behind them by each successive lord-lieutenant, the exclusion of Irish law students from the English Inns of Court, and the treatment of Irishmen travelling in England.

There is no further mention of Fortescue in the 'Patent Rolls,’ nor is anything known as to his afterlife, beyond the record of an action brought against him to recover certain lands in Nethercombe, Devonshire.

[2] He was twice married, each time to an heiress: He left sons by each wife, who each inherited their respective mother's properties, and founded two branches of the Devonshire family of Fortescue.