E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Irena.
The impersonation of Ireland
whose inheritance was withheld by the tyrant Grantorto. Sir Artegal (Justice) is sent by the Faërie Queene to succour the distressed lady. Grantorto, or the rebellion of 1580, being slain, she is restored to her throne and reigns in peace. (Spenser: Faërie Queene, v.)