Hereswith or Hereswitha (), also spelt Hereswithe, Hereswyde or Haeresvid, was a 7th-century Northumbrian saint. She married into the East Anglian royal dynasty and afterwards retired to Gaul to lead a religious life. Hereswith's sister was Saint Hilda (or Hild), founder of the monastery at Whitby. Details of her life and identity come from Bede's Historia Ecclesiastica, the Anglian collection and the Lives of Edwin of Northumbria and Hilda of Whitby. Background Hereswith was the great-granddaughter of Ælle, King of Deira through her father Hereric, who was nephew of Edwin of Northumbria. Around 604 Æthelfrith, King of Bernicia took control of Deira. Æthelfrith married Edwin's sister, Acha of Deira; Edwin and Hereric went into exile. Hereric was married to Beorhtswith/Breguswith and had two daughters, Hereswith and her younger sister Hild (born around 613). By 610 Edwin was at the court of Cearl of Mercia, where he married Cearl's daughter, Cwenburh and by her had two sons, Osfrith and Eadfrith. Hereric sought safety in the British kingdom of Elmet, then ruled by Ceretic. While at Elmet, Hereric died by poisoning, perhaps at the instigation of Æthelfrith. Suspicion fell on his host. By around 616, Edwin had moved to the court of Rædwald of East Anglia. Multiple envoys from Æthelfrith offered bribes and then threats to try to persuade Rædwald to murder his guest or turn him over to them. Rædwald was inclined to do so until admonished by his pagan queen for acting in a manner dishonourable for a king by betraying a trust for fear or greed. Once Æthelfrith's ambassadors had gone, Rædwald resolved on war. Rædwald defeated Æthelfrith at The Battle of the River Idle. With Æthelfrith defeated, Rædwald installed Edwin as king of Northumbria. Northumbria With Edwin now king in Northumbria, Hereric's family became attached to his household. Edwin and Eadbald of Kent were allies at this time, and Edwin arranged to marry Eadbald's sister Æthelburg. Bede notes that Eadbald would agree to marry his sister to Edwin only if he converted to Christianity. Edwin, a pagan, had encountered Christianity at Rædwald court. In 625, she married Edwin as his second wife. Edwin and his household, including Breguswith and her daughters Hereswith and Hild, were baptised by Paulinus at York in the spring of 627. The family of Rædwald's brother Eni began to assume power in East Anglia during this time. East Anglia It was almost certainly in