In response to escalating tensions and previous conflicts with the Danish invaders, King Æthelred II of England ordered the St. Brice's Day massacre, targeting the Danish population residing in England. This preemptive strike occurred amid fears that the lingering presence of Danes could result in a new wave of Viking raids or dissent against Æthelred's rule. Reports indicate that many Danes, including those who had lived peacefully in England for generations, were hunted down and killed as part of this violent decree. The event is said to have taken place across various territories within England, with varying reports detailing the severity and scope of the violence.

Historical records suggest that Æthelred’s order to kill the Danes was a desperate measure to assert his authority amid widespread unrest and challenges to his kingship. The massacre reportedly included both fighting men and women, suggesting a ruthless targeting of the Danish community as a whole. Some historians emphasize that this event significantly exacerbated the existing animosity between the English and Danes, consolidating Danish resolve in subsequent years to reclaim territory from English control. Many of the Danish who survived the massacre would later engage in retaliation against Æthelred’s rule, highlighting the long-reaching consequences of the king’s actions.

The St. Brice's Day massacre is often viewed as a pivotal moment in the ongoing conflict between the Anglo-Saxons and the Danes. It set a precedent for future retaliatory violence and conflict, pushing the two groups into a deeper state of enmity. The fallout from this event helped mold Æthelred’s legacy, with its brutality often overshadowing his other achievements and reign overall. Furthermore, this act of violence was pivotal in shaping the cultural narrative around Viking presence in England, influencing stories and historical accounts for centuries to come.