Mildburh combines the Old English milde (mild) and burh (fortress). Saint Mildburh (d. c. 715) was the Anglo-Saxon abbess of Wenlock Priory in Shropshire — sister of Saints Mildred and Mildgyth, granddaughter of King Penda of Mercia.
Famous in medieval England for miraculous healing.
Mildburh reduces to six — the number of Anglo-Saxon abbess.