Sadalberga was a noble Frankish woman born in the early 7th century near Langres. As the daughter of Duke Gundoin, she belonged to a high-ranking lineage. After being cured of blindness by Eustasius, she married Richramnus and later Blandius, eventually becoming a mother to five children. She dedicated her life to religious service, founding the Abbey of St. John and later moving the monastery to Laon. She died in Laon on September 22, 655.