Bertha was a sixth century Frankish princess who married King Æthelberht of Kent. According to the recorded history of the Venerable Bede, Bertha's marriage included the condition that she be allowed to practice her Christian faith. To this end, Bertha used the church of St. Martin in Canterbury. Bertha's influence was instrumental to the mission efforts of St. Augustine of Canterbury, and when he was sent to convert the Anglo-Saxons, he used St. Martin as a base of operations.

In a letter to Bertha, Pope Gregory compares her to Helena of Constantine and implies that her faith was instrumental to the conversion of her husband and his country.