Adalbert (or Æthelberht) is said to have been born in Northumbria, a member of the Northumbrian royal family.

According to Alcuin's late eighth-century Vita Willibrordi archiepiscopi Traiectensis, they landed near Domburg.

Adalbert is said to have shielded the settlement of Egmond from pirates by causing a fog to arise along the coast.

[3] His continued remembrance rests largely on the foundation of the Benedictine monastery, Egmond Abbey, the first in the country, some two hundred years later by Count Dirk I of West Frisia (or Holland), of which Adalbert was made the patron.

Adalbert's relics were translated to the newly built abbey (initially a nunnery) for veneration.