Britomart's decision to become a knight is linked to her love of Artegall, a noble knight she first sees in an enchanted mirror. A pure and virtuous young woman unaccustomed to love, Britomart is at first disturbed by the romantic yearning the magic image of Artegall inspires in her heart, fearful that these strong feelings will develop into lust, but she soon comes to accept her emotions, even if their turbulence still disturbs her. A visit to Merlin reveals her destiny: she will one day wed Artegall, and their descendants will be rulers of England, eventually culminating in the greatest sovereign of them all, Queen Elizabeth I. However, Britomart must first venture into Faerie Land as a knight to restore Artegall to the human world since he was kidnapped by fairies as a child.
Since she was trained in combat from a young age, Britomart does not go into knighthood unprepared. Her family line includes several examples of warrior women as well, giving Britomart models to follow in her quest. She becomes one of the best fighters in the entirety of Spenser's epic, granted an unbendable will due to her chaste nature and whole-hearted commitment to her quest.