Mildrith was Princess Æbbe’s daughter and thus a great
granddaughter of King Eadbald and great great niece of Queen Æthelburh.
Through her father Merewalh she was also a princess of Mercia, since his father
was the King Penda who had killed her great great uncle King Edwin of
Northumbria at the Battle of Hatfield Chase in 633 or 634.
Æbbe sent Mildrith away to the monastery at Chelles in Francia (the area now largely occupied by France) in order to learn the way of being a nun. At that time in the 670s and 680s, monasticism was much more developed in Francia than it was amongst the Early Medieval English kingdoms. Mildrith would have learned not just what it was like to be a nun but would also have seen what it meant to run an abbey and to support the spiritual interests of the ruling family, her royal cousins in Francia.
Upon her return to Kent, Mildrith joined her mother at Minster, where by 694 she had become abbess. She died sometime after 732 and was initially buried in the abbey church of St Mary. However subsequently her successor Eadburh founded a new abbey dedicated to Saints Peter and Paul, where the abbey in Minster stands today, and Mildrith’s remains were translated there by around 748.
Mildrith became a very popular local saint and her shrine was the subject of much pilgrimage during the Early Medieval period. However, by the 11th Century, most of the old Kentish royal monasteries had been taken over by other monasteries and the abbey in Minster had come into the possession of St Augustine’s Abbey in Canterbury. In 1030, the Abbot of St Augustine’s led a party of monks to seize St Mildrith’s relics and carry them back to Canterbury. When the residents of Thanet living around Minster learned what was happening they banded together and attacked the monks who beat a hasty retreat. However, the monks had already achieved what they had set out to do and they carried away St Mildrith who remained ever afterwards at St Augustine’s Abbey in Canterbury.